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T4 Quadcopter Drone

by Brendan22 Mar 1, 2014
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My print came out great now I ordered the parts I’ll post more when I’m
In flight

What is the average flight time you get with this?

Hi All I've printed the T4 Quadcopter (10" props) use my Ender 3 Below are the print times using 40% Fill 0.2 Layer height

4 X Arms: 3 Hours 30 Minutes (Each)
Body: 18 Hours
Bottom Tray: 5 Hours
Top Plate: 3 Hour 30 Minutes
4 x Long Legs: 1 Hour 30 Minutes (Each)

Below is what i have ordered:
4 X Motors: Turnigy L2215J-900 Brushless Motor (200w)
Transmitter & Receiver: Turnigy 9X 9Ch Transmitter W/ Module & IA8 Receiver (Mode 2) (AFHDS 2A System)
Propellers (CW): GWS Style Slowfly Propeller 10x4.5 Black (CW) (4pcs)
Propellers (CCW): GWS Style Slowfly Propeller 10x4.5 Green (CCW) (4pcs)
Batteries: Turnigy Nano-Tech 5000mah 3S 25~50C Lipo Pack W/XT-90
Flight Controller / ESC: Multistar Razor 40A Tower F4 BLHeli_S

How did those motors work out? Struggling with a good motor choice atm.

The whole configuration is working really well I've recently upgraded to the FrSky XJT 2.4Ghz Combo Pack with X8R 8/16Ch S.BUS ACCST Telemetry Receiver as the failsafe wasn't working correctly and wanted more range.

I've also had to make a few adjustments to the height of the base cover as the components were a bit squished and the long carbon fibre legs didn't work so well so i took them off.

none of your 3dr links work, can you please re-link??

Hmm... looks like 3DR aren't in the same business anymore.

well thats unfortunate. :(

Of course you can build these drones with any other hardware - there are many options to choose from. And I'm sure there are better options now too - it has been a couple of years since I built one of these.

I´m Building your drone just right now. But it isn't as easy to print as you told. . . Now running my 4 try to print the Body... much Problems with my ender 3.

Wish you could do a remix of this awesome drone and make the frame have more of an X pattern. It would just be changing the front arms in more of a X, think it would be really awesome.

Hi, how much does this whole frame (printing only) weight ?

Hi all is there some foldable option for the arms?

Thank you!

Not on this one (only on the TX8).

First flight yesterday (Nov 16 2017). Made three actually but none long enough to run the battery down. I had a some trouble at first but straightened that out and tested some of the flight modes. I used QGroundControl software.

No camera yet but I've ordered a FPV camera and associated parts.

My setup :
Pixhawk Mini FC
T-Motor Airgear 350 motor/prop/esc boxed set
Frsky Taranis and X8R receiver
4500mah 4S battery

Any chance someone could re size the arm and lengthen it 100mm for me. I tried in cura but not sure how to do this. My Anet a2 will accommodate this. Thanks.

have had it done

Hello there Brendan!!
I'm very interested in having your T4 printed, however im a complete noob to both quads and 3d printing.
Aside from the printed parts, what else do I need?
Like, bolts, nuts, etc.
Also, what flight time do you think i could get with the following setup;
APM 2.8 FC with GPS and telemetry
DJI E300 motors and ESCs
Tarot 2d gimbal
Firefly 7s action camera
Maybe an all in one fpv solution
Multistar 4s (biggest one i can fit)
Without battery im assuming an AUW of 1,300kg

Do you have any drawings or component dimensions that you used to make this design? I was hoping to experiment with the design and try to use a lattice frame

What motors would be a good fit for this with 10 in props?

hey bendan check out my made one and tell me what you think! i love the design espesially the battery holder and catch. The guys at my flying feild are interested in the battery locking mecanism for 250 quads. Do you think you could design a box to take 1300mah 4 and 5 cell that uses this locking catch? mabye like a box with velcro mounts on it, with a hole at one end to slot the battery in then put the catch in? currently we are landing on our batteries. We use little sleds but its difficult strapping the battery down tight enough. many thanks dude! this rocks!!!

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hello, may i ask a question?
how much does the 10" propeller set up weighs? i mean the whole thing with go pro, gimball and vtx

Are the arms tapered? They are lose fit and didn't know if they were designed to be snug.

Yes, they should be snug. Perhaps increase your extrusion multiplier a bit (ie pump out a little more plastic).

After looking at it. It might be that these arms are at the limit of my printer. I might turn them diagonally and try again. The arm where it connects to the body is thinner than at the motor mount section. Weird actually

Are 3850's too big for the motor mounts?

if you mean motors with a 38mm can diameter then yes, they would be too big for the standard arm cups (max 30mm). I believe someone has remixed this to suit motors up to 45mm cans here: http://www.thingiverse.com/thing:1824981

T4 Remixed 3D printed Quadcopter

Perfect! Thank you!!

Those 2300KV motors would be more suited for my T4 Mini designs. You'd be looking for motors closer to the 800 - 900KV range for the full sized T4. Something that will run 10" props suits this design (the link you sent indicates it suits 4 or 5" props).

Looks like the right sort of setup. If you have success with it, please post back here for the benefit of others.

hey, I have to re-setup my APM. when it comes to picking the type of frame what is the one to pix? the X or the one like the iris? thanks.

Struggling to remember - I've got a couple of param files with me and they have FRAME: 2 if that helps - not sure what that translates to in the program.

you I just looked at the param in mission planner and 2 is the V.

I see a lot of questions about "what motor to use". Just thought I would share that the T-Motor Air Gear 350 is almost a perfect match for this quad. It comes as a kit, with 920 kV motors, 9545 self-tightening props, and 20A ESCs. The ESCs do require a slight modification to the arm, so I've shared my arm modification as a remix.

Also, just a general plug for this design. I love this quadcopter frame!

Hi! awesome work, i'm just learning my way to robotic and making a drone sounds like a great idea, but i'm wondering on how to control the drone, i don't know how to program the board (just the basics with arduino) or if there are some programs ready to upload. Thanks for your answer

Typically you'd buy a flight controller. If you're curious, the Ardupilot software was originally written for Arduino (albeit on custom boards with extra sensors). See http://ardupilot.org/copter/

anyone else having problems with cracking near the arm inserts. :( every print tried lots of different settings

I did have one socket where I printed the body in PETG and it shrunk a bit causing the layers to split a bit when I inserted the arm.. What I did was use my Soldering Hot Air rework gun (very Useful) to refuse the body back together.

I would highly suggest getting a rework gun it can save many issue and brakes from printed plastic. You can repair the cracks or fuse items together.

Note: When printed with the same material as the arms the shrinkage was the same so no issue was found its when the Body was PETG and the arms PLA that the fit became tight :-)

Will this frame also work with 1200KV motors???

High KV motors (with smaller props) are typically used on smaller quadcopters - but if the mounting on the arms works then no reason why not. Print one arm and try it.

Normally lower KV with bigger props will give you better battery life. The normal objective is to get enough thrust from the 4 props for the copter to hover at around 50% throttle while using the least amount of power. So if your copter weighs, say 1kg, you want a motor/prop/battery combination that gives you just over 250g of thrust at half throttle. too little thrust = sluggish response, too much thrust = difficult to hover/fly/land smoothly.

Great, thanks for the answer

what motor shall i use any suggestions form hobby king
and can i use normal non dji style motors ??

I just did a quick search and something like these would about the right size/power (untested) - http://www.hobbyking.com/hobbyking/store/__25080__NTM_Prop_Drive_28_30S_800KV_300W_Brushless_Motor_short_shaft_version_.html

It's been a long time since I've bought any motors so hopefully others can chip in with current recommendations. Yes you can absolutely use "normal" motors. :)

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can i use outrun motor on this and why is t4 arm x8 for ??

Sure the normal motors are outrunners.

I seem to have a problem with weight distribution ,the battery i have bought is the one you linked and if i have it all the way in it will always wana go forward whenever i lift off ,IF i stick it half way out(it goes in roughtly it swelled a little bit) it will lift off level. Any suggestions?

Normally quadcopters are a little immune to weight distribution issues as the flight controller will just spin the necessary motors faster to keep level. Perhaps check that your flight controller has its accelerometers calibrated level.

Regarding balance, you should be able to roughly balance the T4 on your finger under the centre of where the flight controller would be mounted - assuming no camera/gimbal is weighing down the front.

I have the kk 2.1 hardcase flight controler and i have put the quadcopter on a board i have used a
spirit level(http://www.fesconstruction.co.uk/Level%202%20Unit%2010/spirit%20level.jpeg) on it. its completely level. Anything else i can do to fix this?

Have you been through the full KK2 calibration process? This video might help with adjusting the auto-level pitch offset: https://www.youtube.com/watch?v=7KSof_L6vik

Yes! thanks alot that did the trick, sorry for the bother ,i'm fairly new at this :(

I often use these arms to show people how strong 3d printed stuff can be. I've challenged many people to break one and no one has even come close yet.

I'm planing on building this, what receiver did you use?

I've got a few different transmitters and receiver combinations. I'll need to take a look at my T4 to see which one I used on that. There are probably newer/better options available now though.

I printed an arm and the test fixture to put the arm into, and I got it in, but I can't seem to get it out LOL

Would you reccomend scaling the base a tad bit bigger? Or should it be REALLY snug

From side face-to-face the arms should be 25mm and the socket 25.2mm (so 0.2mm of clearance) which is a firm, but snug, fit. Of coarse it depends on your printer. If you are extruding slightly more plastic then everything you build will be slight over size. Try measuring the parts (or some other calibration method) and perhaps drop the extrusion multiplier a little if they are too big.

Exactly what receiver did you use?

Im planning on printing this in glow in the dark PLA, well post pics when/if complete.

I see you havent done any updates on this copter for awhile, do you feel it's reached a "reliable" state?

Consistently over 500 downloads a month and I'm sure any issues would surface in these comments.

Hey Brendan, have you any plans for releasing a v2 design? :)

how long are the arms?

About 216mm (8.5 inches)

i see they don't sell the motors they call out for in the part list. what would be a good differnt set?

Get motors like the DJI or 3DR ones with the threaded prop attachments built in. I advise against getting any with a prop adapter because one good crash and the shafts are bent and no longer usable. I will find a link and send you some examples.

I had the ones from the link to 3dr but they don't sell them anymore...but ya a link you have would be great...

Check out these. They even have extended wires so you don't have to solder them. http://r.ebay.com/2IPCTl

what prop do you use with this motor setup?

I have been using 10x4.7 props. I had a really bad crash yesterday that will cause a rebuild and I just got in some 9x5 props that I want to try but ironically I wanted to wait until I was crash free for a while.

This crash was not a normal crash. It included an accidental switch to Auto and a random waypoint that was almost a mile away. By the time I realized I could not get it to come back. It came down on a car that was doing 50mph and bounced off their windshield. I was able to find it because I had telemetry on my laptop. I had lost signal but regained it when I got closer. I got yelled at but luckily no damage to the car was done. I quickly picked up the parts and came back home.

sorry about the crash. ya i have 10x4.7 props as well but what type of prop nut do you use? with the motors..

I have DJI style nuts for some props but I mostly use self tightening props with the threads built in. I just search Amazon and eBay for DJI Self Tightening propeller and find various sizes in the 9-10" range.

cool. going to order tonight

Yes I would like to know too.

I'm hoping someone else in the community will respond to this. It has been a very long time (>18 months) since I have bought motors.

I wonder if it's possible to pack Pixhawk inside and just keep the GPS Antenna out?

Is the bottom tray printable without supports? It looks like where the bolt holes are would need support...

You shouldn't need support. The bolt holes use a little 3D printing trick I came up with. The first 0.25mm layer is solid (ie there the hole doesn't go all the way through) so it prints just like any other small bridge. The hole only starts from the 2nd layer upwards. That single first layer is so thin that when you are assembling a bolt will push right through it an you wouldn't even know the hole doesn't go all the way through.

Awesome! Thanks for the quick response. I am about to print it on an Ultimaker and I will report back the results. I am about 50% done printing the T4 and have most my electronics! I can't wait to get this thing in the air!

What gimbal do you use for your go pro?

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what motor should I buy from hobbyking ?

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My motors overheated today and went through the mounting holes in the arms. I used the 3DR motors from the instructions and the 4-in-1 ESC. I've only done a few flight before, during last weekend, when I didn't notice anything.
Today I first flew with a 3S 6000mAh battery (maybe 15 mins) and then changed over to a 4S 4500mAh one. Both are of very similar size/weight. Could the voltage be related to more heat? I wouldn't really think so and rather attribute it to the heat building up over time.
Later at home I fired it up while holding it down and it didn't take long for the screws to get really hot again :(
Can someone refer other motors that keep cooler?

That sounds really unusual. I just did a 15 minute (full speed forward) flight here and checked the motor bolts immediate after landing - they were not even warm to the touch (if anything cooler that my finger temp). It is a nice winter day here 18 deg Celsius. I was using a 5200mah 3S battery. All up flight weight 1.3kg (no camera). Admittedly I bought my 3DR 850KV motors a couple of years ago now so they may be different.

Out of curiosity did you print your frame using PLA or ABS. It almost looks like ABS in the photo. If so, make sure you don't use any sort of locktite on the motors bolts as it eats ABS making it really brittle very quickly. For what it's worth I use a small washer on each motor bolt too (albeit I only use 2 bolts per motor).

I had started printing the arms in PET (t-glase) but ran into issues later with the process, so 1 arm is PET, the other three are PLA. The PETmanaged the heat much better than the PLA.
I just watched some of the footage and you can see and hear that there are issues only a few minutes into the first flight. I wonder why, as last weekend I flew much longer and without issues with pretty much the same setup.
Can you recommend other motors, ideally sourceable in NZ? 3DR's service was pretty rubbish so far, so I'm not holding my breath getting mine replaced :(

Also I just took a look at the datasheet for those motors and note that they mention 8" props for 4S batteries - perhaps 10" props are too much for them with 4S. Datasheet here: http://3drobotics.com/wp-content/uploads/2013/11/A2830.pdf?_ga=1.110123333.177976144.1411158011

Thanks Brendan, I'll look for other motors....

Hi Brendan22. Thank you for this quadcopter, really enjoy doing and fly. I write to you because I have trouble adjusting the PID. could you share me a pic of set that you have, it will help me a lot to get away from the "turbulent" flights.
Thank you.

PIDs are something that will be specific to the Flight controller / Motors / ESCs / Battery / Payload and possibly even the firmware version that you are using. Unless we have exactly the same configuration my PIDs wouldn't be much use to you.

I know this is not the 'ask Brendan which works' thread, but what the heck :)

I've got a Tri I built using these motors:

Using the Turnigy Plush 25A ESCs, and some 12" props .. pretty beefy stuff for slow and stable for noobie.

I'm wondering though.. if the Tri proves too difficult for noobie to fly, maybe a quad would be more stable (an more carry capacity, as I'm using heavy batteries and wiring). I've got I believe the same battery you recommend, plus a smaller one.

Given 3 of these can carry the Tri, I'm better 4 of them can carry the quad; mind, I'm used to 10+ inch props and I think you've got.. oh wait, T4 is 10", was thinking it was 8".

... you think going from 12" down to 10", but adding the extra motor.. 850KV .. am I in good standing?

I am trying to avoid having all sorts of different parts around, trying to stick to a core set (for spares and parts ease :)

Tri is nice, at least it can fold up to store it, but its pretty challenging to maneauver!

Those motors look fine for 10x47 props - not sure if they'll physically fit in any of the motor "cups" though (large diameter). You might need to use the X8 arms and bolt the motors on top.

Thanks! Though I suspect its my total noobness more than the designs in question .. 'what do you mean you can use throttle curve to smooth out the important part, making bobbing a lot less frequent?' :)

For those in the US looking for metric bolts, I have had good experiences with Mr. Metric. http://www.mrmetric.com

Ship pretty fast and have had most everything I have been looking for.

Hi Brendan, great desing!!
Today I've finished building the 315 T4 and unfortunately severely crashed it on the first flight. I've uploaded to Thingiverse (in the I made one section) the last pictures I took of it. Lost an engine and an ESC on that crash, but the remaining seem to be ok. As you may suspect 4 30 Amp ESCs where too big for the 315 quad so I had to modify the bottom tray a little. That kind of worked but I believed there wasn't enough cool air flowing and that may have burned one of them. The motor broke on the impact.

Now I am about to start printing the T4 full size because I loved the design. I would like to use the 3 motors, ESC and battery that survived (Sunsky 980 KV, 2200 mAh 3 Cell battery and 30 Amp Simonk ESCs). Do you thing those components will work for the T4?

Thanks in advance!

Sorry to hear about your crash. I'm no expert on motor combinations but I can offer the following guidelines:

  • research the prop data for your motors and then...
  • you want props that your motors can handle (ie not so big that your motors burn out)
  • you want to props that provide a combined thrust equal to twice the all up weight of your T4 (ie 50% thrust for hover)
  • you want a motor/prop combination that draws the least amps possible at hover (for longest battery life) and is well within the current limit of your ESCs at full throttle.
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Any suggestions for a charger for a 3S 6000mah battery?

Brendan, I am in the process of wiring up the Pixhawk, to the QBrain 4 in 1 ESC. I am planning on attaching the QBrain to the body as shown on the picture you provided ( above picture scrolling area). With this layout for the QBrain, what is the wiring for the Pixhawk? On the QBrain I have 4 plugs with wire colors as follows: Plug 1. ) Black-Red-White Plug 2. ) Red Plug 3.) Orange Plug 4.) Brown. I know the wires connect to pin 1 thru 4 on the Pixhawk.

Also are you using the default programming or the QBrain?


This picture might help - http://copter.ardupilot.com/wiki/advanced-pixhawk-quadcopter-wiring-chart/

I usually don't connect the 5V supply from the QBrain (assuming you're using a 3DR power module) so the Black-Red-White plug will only have the black (ground) and white (one of the motors) wires connected. The other "single" wires are connected to the other three motors outputs. The order of the motor outputs is a bit of trial and error - move them around to get the desired result (http://copter.ardupilot.com/wiki/initial-setup/assembly-instructions/connect-escs-and-motors-pixhawk/).

I haven't changed anything in my QBrain - just calibrated it (http://copter.ardupilot.com/wiki/initial-setup/esc-motor/).

Bendan, I am in the process of printing two of these for my twin boys. I have one of them fully printed and starting to assemble it. The other is being printed as I type. In addition to all the parts, I need to buy each a Transmitter and Receiver. Would something like this Turnigy 9X 9Ch Transmitter w/ Module & 8ch Receiver (Mode 2) work for a T4?


Great to hear that you are printing a couple of these for your boys. The Turnigy 9X is great value. The most important thing is that the receiver will operate well with whatever Flight Controller you decide to use.

Being that I am total new to this, I am working directly from your list. I have purchased (2) Pixhawk, the (8) 3DR 850KV motors, (2) QBrain 4 in 1 ESC, (2) 3DR GPS/Compass and so on down your list. Do you see or know of any issue with using a Turnigy 9X with a Pixhawk?


The Pixhawk only has provision for a single cable PPM receiver connection (not an 8 PWM cable connection) so you probably need a PPM encoder as described here: http://learnrobotix.com/uavs/quadcopter-build/pixhawk/connecting-turnigy9x-radio-pixhawk-flight-controller.html

Thank you for the information. I will post some pictures once I get the two T4 finished.

Thank you for the information. I will post some pictures once I get the two T4 finished.

Hey Brendan. I love this design. My quad is in the air and flying great. Thanks for all the great tips in your instructions. I know a quad isn't supposed to spend much time upside-down in the grass, but due to my newb-ness I've already discovered the weakest point. This being the GPS mast mount on the top plate. One rough landing with a bit of forward momentum caused mine to flip in the grass and broke the mount rather than breaking the mast. Oh well. Lesson learned. Thank goodness for a 3D printer. I can print another plate and focus on actually learning how to fly!

Thanks again!

I started printing this out last year, then got sidetracked. i have all the parts. I'm having a hard time printing the legs though they always want to curl up off the bed plate and end up bowed. I modified them with big skirts on the ends but they still pulled up. I'm using a Replicator 2..although my replicator 2 is modified with bottleworks aluminum arms and heated built plate. so I have a heated built plate and glass surface. I have been printing onto blue painters tape with PLA and no bed heat. Will bed heat help? how much.

I use budget hairspray on glass heated to ~55 degrees Celsius. At one point I used one of those cheap Infra-red temperature guns to measure the temperature along the length of the part (after it was about 1/3rd printed) and compare with the temperature of the build plate - my theory being to get them as close to each other as possible. I suspect the issue with long skinny parts is keeping the temperature as close as possible along the full length of the part so it's good if the headed bed element extends all the way to the edges of the build platform. In saying all that my arms repeatedly print fine without any "skirts" - in fact I typically have to put the glass into the fridge/freezer to get the parts to release (once they've cooled down).

Bed heat with PLA worked like a charm thank you.

Ok I'll try some heat. and probably leave the blue tape on ( it really really sticks to the blue tape ).. I usually ruin the tape removing items. Office Max Glue stick seems to work pretty good for ABS and PLA on the glass as well. I have a full enclosure kit now too and am printing the lower tray currently with no bed heat.. i think the full enclosure is helping keeping temps consitant.


Thanks for this. I've printed it and turned out beautiful. Now i'm waiting for the motors and other stuff to arrive. One question for you. I should be able to find the answer on the net, but not conclusive. I'd like to get this flying with the bare minimum equipment. I eventually want a camera and GPS, but right now, just to test fly it. What exactly do I need right now? I ordered the motors and props, the battery, and the 4 in 1 ESC. I'll get the transmitter soon. Is that all I need until I'm ready to go crazy? Thanks.

You'll need some sort of flight controller (KK2, Naze32, APM, Pixhawk, etc), a 6+ channel receiver to suit your transmitter. Battery socket to suit the plug on you battery, bolts, nuts, heatshrink, perhaps wire to extend your motors/ESC connections. There always seems to be something I forget :)
There are some images and info that might help...

What motors could you recommend to use with this frame (instead 3DR 880kv)

I want to use this ESC:http://www.hobbyking.com/hobbyking/store/__42715__Q_Brain_4_x_25A_Brushless_Quadcopter_ESC_2_4S_3A_SBEC.html

And want to order motors also from hobbyking to save money on shipping. They don't have 3DR motors.


WARNING DONT SCREW THE SCREW IN TOO DEEP lol i messed up 8 pairs of motors until i realized thats what i did. X)

That's the ESC I'm using too. I haven't had any experience with and HobbyKing motors in this size sorry. The 3DR motors come from 3DRobotics.com in the US.

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Attempting to print in ABS, just because. I will update with the results.
Printing a LEG, then the main BODY. If those work I think I am in the clear!

-- Update one end curled on the leg. I am going to print in PLA to see how everything should look, the try again in ABS. This will be very difficult to do in ABS as an small amount of warp can impact the flying.

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This is fantastic - been looking for a new frame for a while now - printer is heating up as we speak.
Haven't played around with sketchup much but is there any chance of getting an arm variant to accept 35mm outrunners?
I use these guys (http://www.hobbyking.com/hobbyking/store/__25556__AX_2810Q_750KV_Brushless_Quadcopter_Motor.html). Seem to be super efficient - would be awesome to port them across to this frame if I could :-)

I am having trouble reading two of the STL files. I am thinking that the files have become corrupted. I can read all the other files without any issues. Would it be possible to re-upload the T4BottomTray.stl, and the T4TopPlate.stl files.


I just downloaded these files to test and they loaded fine in my slicer (Simplify3D).

Thanks checking. I am using Cubify Cubepro software. I was able to fix the files using Simplify3D. For some reason the Cubify software was not able to read them, so I exported them using Simplify3D. Once that was done I was able to read them. My next task is to setup Simplify3D so I can use it directly.


Very cool! Only problem I have is that the body parts don't fit in my Kossel Mini print bed. The arms do, though, and I'm re-using those, and remixing the body to be able to be printed vertically (17cm diameter printbed, but 24cm tall volume!) Will post a link with the remix when I'm done.

Have anyone put any thingiverse propeller guard to T4 10 inch propellers?

I flew this quad for the second time today (the first flight was very short) and I had a very frightening problem. After ~9 minutes of flight, the quad dove hard to the front-left and almost hit a tree. I struggled to bring it back and land it but I got it back in one piece with a pretty hard landing. Inspection revealed that the two front motors had gotten so hot that they had started to melt through the PLA arms and pull the bolts through the arms, making them wobble. I fear that if I had been flying for just a few more minutes I would've ended up with both of my front motors no longer connected to my quad, and I think we can all imagine what happens after that.
I'm using the 850Kv motors and 10x4.7 props linked to in the recommended parts, both directly from 3DR.
Has anyone else had this happen to them? If so, how did you fix it?
I was thinking that I could put a few holes in the arms where the motors are to provide a little more cooling, but I don't know if that would be enough.
Any suggestions/thoughts would be greatly appreciated.


Have you solved this problem? I had exactly the same happen to me today with the 3DR 850KV motors from the instructions :(

Nope. My quad ended up going splash into the water while hovering at 10ft. I recovered it and sent the logs to 3DR but they basically said they didn't know what happened and couldn't help me. I did put washers and cut out a big portion of the arms around the motors. Check my other comments for pics

Oh, sorry to hear that :(

Also, just a few more things

  • The two rear motors showed no signs of melting/overheating
  • As it was my first flight, I spent almost the whole time just hovering. I only went full-throttle once for a few seconds

I can link pictures if necessary

Wow, something must be wrong if they are getting that hot! Mine only get warm to the touch. Do they spin freely by hand? Are you using a 3S battery? Are you carrying any extra weight (particularly in the front of the Center of Gravity)? Does your T4 hover at about half throttle?

They spin pretty freely by hand. They're not buttery smooth -- they have a little bit of resistance, but I don't think that's abnormal. The prop spins around once or twice with a decent push. I'm flying with a 3S 5000mAh battery. There's no extra weight -- I'm not even flying with a GoPro or gimbal. It hovers at about half throttle in Stabilize mode on my Pixhawk, but I'm not sure if that's just because it auto-adjusts the throttle output.

All of that sounds completely normal. With the battery inserted, does the T4 feel pretty balanced if you put you finger approximately under the centre of where the Pixhawk is mounted? Perhaps trying moving the battery back as far as can (pad the front). Otherwise try swapping a front and back motor and see if the problem stays at the front.

I have the battery all the way forward in the slot. I'll try moving it back and see if that fixes the issue. Strange that just a few inches would cause the motors to get that hot... makes me concerned about flying with the added weight of a gimbal+gopro

Yep something is not right. I've flown regularly (and vigorously) for 15+ minutes on 30 deg C (86 deg C) temperature days and checked the motors afterwards - they feel warmer than ambient but not hot.

I attempted to get better cooling by cutting some of the surrounding arm away and drilling a few holes. Here's a link to what they look like now: https://drive.google.com/file/d/0B-qtV1iJCOXoZUpUTkY5eHB0S1E/view?usp=sharing

My first flight after doing this lasted ~13 minutes. Every few minutes I stopped and checked the motors to see if they had gotten hot. They were slightly warm but not hot after the first flight. I changed the battery and started another flight. A few minutes in I started to hear some oscillation, so I landed. Two of the motors (front right and rear left) had done the same thing as before and were starting to come loose due to getting too hot. All 4 motors were very hot to the touch. At this point I'm not sure what to do. I guess I'll give 3DR support a call and see if they've changed anything in the design of their motors recently that would be causing this.

I just realized that I have the props secured incorrectly. I put them above the little collet, but in your pictures the collet is above them. Could this be causing my issues? Seems unlikely that a few mm's would cause this.

I wouldn't expect the height of the prop to make any difference - but perhaps mounting that way is resulting in an imbalance -> more vibration -> more heat generated by the bearings??

I see that in your video with the GoPro + Gimbal you're using the 880Kv motors. Have you tried flying with the 850Kv motors with the gimbal+GoPro?

I can't remember :-) I mostly use my T6 for carrying the gimbal and camera - and haven't had much time for that lately either :-(

Finally had a chance to auto tune. Remarkably stable though it flew quite well even before auto tune. Winter up here been 15-20 deg F and still
getting 15 min flight time minimum. I sit in the living room by the fire place and fly it from inside looking out the picture window. Once again a very thorough design. Much appreciated.

una version para incluir la naza dentro del frame seria perfecto

Hi Brebdan22, great work!!
I have printed the T4Body seems good, but the space for the accu is small. I need 5 mm more space left or right and 30mm from the end for accu cables. I will use my 3s Hacker Eco-x 5800 mAh. Could you help me with an "custom" Body?

Sorry, what is "accu"? I'm a bit pressed for time at the moment. The source Sketchup CAD files are in the downloads - perhaps someone near you may be able to help tweak the design and you could post it back on Thingiverse as a derived thing?

Thanks for your quick answer, a accu means a rechargeable battery pack - accumulator.

Hello my name is Vince Corey. I'm a senior at Hewitt Trussville High School in Alabama. I'm doing a senior design project for our 4th year engineering class and we are making a quad copter for search and rescue using your frame, a Qbrain 4x20A esc, and 3d robotics 850kv motors with a turnigy nano tech 3s battery. We ran into a problem when we tried running our motors, we first connected them and turned the esc into programming mode and programmed it to a lipo battery and calibrated it. when we went to test to see if the motor would spin it would twitch and smoke . We checked all the connections and it seemed like they were all good we tried 3 different motor and had the same results.

Hi Vince. It is great to hear you are using the T4 as a project for school. Disappointing about the motor issues though. I've not seen that problem but if it has happened on more that one motor then I'd suspect the ESC instead.

Double check your wiring is set up like this: http://copter.ardupilot.com/wiki/advanced-pixhawk-quadcopter-wiring-chart/

The QBrain should drive the motors fine on default settings (albeit with a calibration later - after everything is connected - motors/flight controller). Perhaps it is faulty or a bad setting was selected by accident? I think each of the 4 QBrain ESC outputs are pretty much independent (even when programming) - have you tried another output? Otherwise do you have another single ESC that you could use to test the motors are still okay?

What is the lenth of the arms? I could not fing them listed. I have a prussa i3 and wanted to print this frame

Thank you

216mm - you can always place them diagonally on the print bed if it is a tight fit.

I'm writing down a list of stuff i need to buy so i can build this beast. I just wanted to check with you if you recommend any other motors. I'm no expert but as far as i know lower volts and bigger props are better, so i came across this motor and was wondering if i should use it with either a 11x5.5 or a 10x7 props(and which you think might be better) - http://www.hobbyking.com/hobbyking/store/__44295__NTM_Prop_Drive_28_30S_800KV_300W_Brushless_Motor_short_shaft_version_EU_warehouse_.html

I think 11 inch props might hit each other (between the front an rear motors). I'd stick with 10.

Hi again Brendan - i'm in a bit of a pickle, namely a tight budget and the question about flight controllers (it is very important that i have autopilot). Can you please give me your opinion about:

  1. http://www.hobbyking.com/hobbyking/store/__56052__HKPilot_Mega_2_7_Flight_Controller_USB_GYRO_ACC_MAG_BARO.html

I'm not even counting KK2 as an option, because this is my first build and i don't want to bite off more than i can chew.

I only have experience with KK2 and Ardupilot (APM and Pixhawk) flight controllers. I changed from KK2 to APM pretty quickly because I wanted return-to-launch in case my RC control failed. I haven't actually done many antonymous flights with it but the "follow me" and "drone selfie" functions in APM version 3.2 released recently are pretty cool.

I got a couple of the HK Pilot APM clone controllers here and they work fine. It's hard to know if the ebay clone one is any good.

If you go the HK Pilot way though you'd really want the combo with LEA-6H GPS, power module and telemetry ($180). Be aware though that the current firmware (3.2) is the last version that will run on the APM 2.6 generation hardware - version 3.3 APM firmware onwards will only work on the newer Pixhawk generation flight controllers (or in Hobby King clone terms the HKPilot32 hardware).

Well i settled on

But i decided to save some money and opt out of the telemetry(unless you know a dirt cheap option). What do you think?

P.S.About that motor i sent you before - i noticed it's a "short shaft" version, which is more powerful than the standard one, but i just don't know how you will mount the propellers on it:

I read somewhere that i would need a http://www.hobbyking.com/hobbyking/store/__16719__NTM_Prop_Drive_28_Series_Accessory_Pack.html for the short shaft version, do i need to use it for the standard one. I will use these props:

I really want an experienced opinion before i buy anything, sorry to bother you so much but i'd really like to hear what you think.

EDIT: Did you know about http://www.goodluckbuy.com/3d-printed-alien-4-axis-quadcopter-frame-kit-rc-multicopters.html ?

Every combination of parts is an unknown. I tried mixing and matching motors, props, etc as you are doing and eventually gave up (after wasting a lot of money) - the paper specs often differ from reality. Mostly they flew but weren't as efficient as I wanted or as reliable.

I decided the best approach was to use a combination of bits that had been researched and proven by someone with a lot more resources (time/money) than I had. In the case of the T4 I believe the 3D Robotics Iris is a very close match in size and capability so I now use the 3D Robotics motors and props and have no problems (and their motor price was the same or less than Hobby King anyway). I've found they work fine with the QBrain 4-in-1 ESC and, if necessary, clone APM flight controllers - although I recommend the genuine 3D Robotics Pixhawk if you can afford it.

Very thorough, thank you. I met with local RC hobby group and i asked their opinion about 3d printed copter frame and they were all quite sceptic. I understand that it's hard to compare 3d printed plastic with aluminium, but i won't be racing my drone - it'll spend it's life flying around slowly and taking photoes so i don't think the arms will break mid flight, however they did mention that printed frames tend to vibrate more which distorts the image. They recommended using these two frames -

However i am sceptical. I don't think the image(or video) will be that much worse if there even is a difference. Especially when you take into account that your frame is a bit lighter and cheaper and it still shoots great videos. What do you think?
Also do you think a printed gimbal will do a good job?

I've built aluminium and 3D printed copters. They will all vibrate unless the props are balanced. As you can see from one of the screen shots above, the vibration on my T4 are minimal (and less that some of my aluminium attempts :)). I have no concerns about the strength of the T4 and at least you can print new parts if you do fly into a tree or something - beats waiting for a courier to arrive! In saying that there are so many cheap off-the-shelf frames out there that you'd probably only bother 3D printing one if you are a bit of an enthusiast. Buying a proven RTF machine is probably the best way to get started.

With cameras you pretty much always need some sort of vibration isolation. My preference is a hanging gimbal that uses dampening balls (like the Tarot T-2D). Printed gimbals can work well if you get the right motors, controller and tuning.

You have been very helpful thank you - i think in the end i'll print it, i can always use the parts on an aluminium frame if the printed one doesn't work out. I'll keep you posted.

I just remembered something - i read in the description the fully equipped copter is a bit over 1 kg, can you tell me how much the frame itself weights?

the kk2 is by far the easiest to setup using stock settings will almost guarantee stable flight out of the box
after setting up almost every flight controller at least once, for a beginner that would be my first recommendation and be less of a bite to chew so to say

OK so my information that it is difficult to work with is misleading, but as far as i know it doesn't have Waypoint
Navigation or position hold functions (i'm not sure it even can auto level). And i am looking for a cheap alternative of the NAZA-M V2..

Do you have any experience with the other two options - the APM clones i sent you?

I have a kk2, apm, naza, cc3d and a few others I have used like naze and wii based fc's. The kk2 does stabilize (auto level) but no waypoints :( The apm is not a beginner's choice or as simple as a naza or kk2 to setup but if your looking for waypoints there's no easy way out and your going to have to jump in and have patience and expect to replace parts trying

Hi Brendan22 i was wondering are you willing to make this drone and sell it? And with all electronics included

Thanks for the query. I don't have any plans to do that - just a hobby for me.

Brendan, can you upload files for a seven inch arm?

"Seven inch" as in for seven inch propellers? or something else? The source Sketchup CAD files are in the downloads if you want to make a derived Thing.

Hey Brendan22, i just got my tarot gimbal. how are you powering yours? i was going to put in a small battery.


I've done both. At one stage I had a completely independent bottom tray with it's own small 850mah battery. That allowed me to swap the "gimbal" tray with a "blank" tray. But managing two batteries can be a pain so at the moment it is powered from the main flight battery,

Can anyone point me to a good electronics guide for a newbie, I have a apm flight controller its not the 3dr its a clone, but I am having issues getting it to calibrate and arm. Thanks.

The only really good resource I know of is the ArduCopter Wiki: http://copter.ardupilot.com/wiki/table-of-contents/

My first attempt to print the body failed ... Took 17 hrs (I accidentally turned on Supports, and it added print-time also ) :-(
At 95% something happend and the body moved a few mm and got spoiled, eahhh

You use Simplify3D right? What settings do you use for Print Quality?
I used "Medium" in my first try, and was thinking to give "Fast" a try now (8hr print time), but not sure if quality will be good enough?
What do you think? Btw, I'm using a Flashforge Creator printer ...

Damn. I know how that feels when a big print fails just before the end. I had that problem trying to print one of the bird houses on here - turned out my bed was too loose on it's springs and was bouncing around slightly when prints got taller. Anyway, yes I print using Simplify3D on the medium print quality = 0.25mm layer height on my MakerGear M2 printer.

You use hairspray to get it to bond, right?
I tried it before, but it failed, but I went out and bought an XXX strong cheap hair spray now, to give it another try.
But still, it didn't bond :-(

I heat the bed to 70C and print on a mirror glass that I sprayed a layer hairspray on and let it dry.
The nozzle I heat to 215 first layer, then 210 for the rest. The cooling fan I planned to have off for the first layer.
But already after just a few sec I could see it didn't stick and i aborted after a min.

Only way I can get it to stick is if I use a wood-glue-water slurry and paint the glass and let it dry.
But if I could get hairspray to work it would be much easier...

So, how do you do it? What temp settings do you have? Any hints???

The hairspray I use just a basic budget type (not XXX strong). I run the heated bed at 55C - hotter and it seams to cause curling.
My only other pieces of advice are:
1) get the first layer height right. The first lines should look slightly fatter than a normal bead bead of plastic because they are just a little bit squished onto the bed.
2) print the first layer slowly. I'm printing the first layer at 2,880 mm/min (60% of my normal 4,800 mm/min)

I went back to glue-slurry and so far the body is printing fine ... 62% done now :-)
When done I will do some more hair-spray test to see if I can get it working ... I might had too hot bed ... 70C
It's all about testing and testing with that hair-spray, until I get it right I guess :-)

Also, I don't know if the type of glass makes any difference but I'm using the Borosilicate glass (like Pyrex) that was supplied from Makergear with my printer.

For what it's worth I find this process very reliable and repeatable ...as long as my first layer height hasn't crept up too much. I've just finished printing of fifty (50!) Raspberry Pi cases for a project I'm working on (1.5 hour print each).

I'm using plain mirror glass I bought locally ... Maybe the type makes a difference also!? Anyway, that's what I got...

And ... Got my body printed okay :-) Now I'm printing the bottom tray, 65% done and still going strong ...
I still use my glue-slurry, that works for me at least ... The body got stuck so I hardly could remove it, so before next print I will add some more water to it ...

Btw ... I might ask you later a little about electronics ... Never had any quad-copter before, so this is new terrain for me ;-) ... But need to print all parts first!

Yeah, shit happens ... It was my active cooling fan duct that moved slightly down and hooked into the body and pushed it a few mm sideways ... Spoiling the print totally ... I used this one: http://www.thingiverse.com/thing:295317

Now thruit00 released version 2: http://www.thingiverse.com/thing:537918
that I have printed, mounted and testing now ... MUCH better mounting, cannot move :-)

Once my test print done, I will give the body a new try, hopefully it goes better this time :-)

Active Cooling Fan Duct for Replicator 1 / Duplicator 4 / FlashForge
Active Cooling Fan Duct v2 for Replicator 1 / Duplicator 4 / FlashForge / CTC

Great copter :-)
I'm going to start printing mine very soon ... Just thinking what colors I'm gonna use :-)
Those .stl files, are those latest version? And do I need to print them all?

The STL files are all the latest. Check out the instructions tab for which ones (and how many) to print.

Got it! ... I started to print the first yellow arm now :-)
I print on mirror glass coated with a thin layer of wood-glue-slurry ... It stick nice and no warps!
I have tried with cheap hairspray, but it didn't stick well ... Maybe it was just to ... cheap ...

Anyway, I'll keep you updated :-)


got mine flying, i like it better then my old 3dr frame with APM 1.0. now to install the Pixhawk (have 2.5 in it now) in it and see how this goes. great quad, now i want to make the mini.

Great news - well done!

Brendan22 and other T4 owners, how many amps do your motors use while on a stable hover? Mine are using a combined 25 Amps, I think that is quite high for a copter of this size.
I wonder if my motors are not sized correctly or if that's a typical current consumption for the T4

From my old notes about 14 - 19 amps at hover depending on the size of the battery (3,500mah - 6,000mah) - and without a camera / gimbal. Ah, but it's been so long since I've had time to fly :-(

Hey, Brendan22, i have the qbrain. how do you calibrate yours?

It's been a while but I'm pretty sure I did it through the Pixhawk (see Wiki). The only trick with the Pixhawk is to make sure you press the safety switch at the right step.

ya my problem is i am using a apm 2.5. i think i have the output to the brain setup correct. i dont get the sound from the esc.

how hard is it to make the holes from 3mm to a 6-32 bolt. I am in the US and hard to find 3mmx40 bolts.

ya a 6-32 bolt is about .48mm bigger then a 3mm bolt. wish I knew how to use sketchup... time to learn..

I'm not very good with bolts sorry. I though 6-32 was 6/32" = 4.8mm. You may be able to drill out the existing holes to use an 1/8" (3.2mm) bolt?

Do you know roughly how much it cost

About 400g of plastic so roughly $16 - $20 for the frame ...and then it depends on what you want to use to make it fly, FPV, radio control gear etc. For mid-range components you might use something comparable to the 3DR Iris. RTF version is about $750 US http://store.3drobotics.com/products/iris

Comments deleted.

it's funny. I did the test socket. works good. but when I print the main body I have to file the top bridge part. but on the test I did not...

The same happened to me on my first print. The model is big and the heat differential is causing the corners to peel off the table.
I suggest using budget hairspray and a glass, sandblasted table if you can.

ya I forgot to cut down the length of the motor wires and on the qbrain. they should be ok at full length?

Should be fine as long as you can squash them in. Mine were like that for a while.

This is one tough frame! it just survived a crash from a height of about 15 ft. It only broke the legs, GPS post and the bottom tray. The main frame and the arms seemed to be unaffected. I printed everything at 30% fill and 2 shells.

One of my concerns is that this body is much heavier than my previous frame (an X525), and honestly, I think it was that what caused a prop to slip off the shaft on a hard turn. (I know, I should have checked on pre-flight.) but the fact that I can print anyting that breaks kind of makes up for the shorter battery life.

IMHO, looking at the frame I think there is some extra material that could be trimmed to save some weight. For example, the exterior wall that gives it that nice round "butt" is not really needed for structural integrity, maybe it can be thinner or taken out. Another heavy spot is the area between the two rear arm sockets, maybe a lighter lattice structure could provide similar function or maybe a few holes can be cut off the octagonal joint and sockets to lighten it up a bit without loosing too much strenght.
Just my 2 cents, I love the look but that's over half a kilogram of plastic!

I'm surprised to hear your comment about the weight. As per my notes on the Instructions tab, my body print clocks in at about 147 grams.

My body weights 185 grams, maybe I am doing something wrong (the 1/2 kilo was for the whole thing). but nevertheless, maybe you could take a look at replacing the heavy rear jount with something a bit lighter? I think it's a tad too massive.
I hope you are not taking this as a critisism, I mean it as a positive feedback.


I am a fan of your work, you do a great job. I am trying to modify your design here of the T4. Or should I say retrofit it. I am having trouble reshaping the cover. I also use Sketchup, I have Sketchup pro 14. I have some legacy arms from a Iris Quadcopter and I want to use your basic shape for them. I am trying to create Top and bottom shells and 2 inner plates then sandwich the lot together for a complete body. I made the plates they are not the problem. But the shells are a different issue. I am as I said retired and can use Sketchup "fairly" well. But when I try to take slices out of the edges of your model nothing seem to fit and the model integrity is compromised. I know Sketchup is not the perfect modeler, but it is fine for most of my requirements. I am having issues with the offset edges. Cutting new holes etc. I am sure it is my lack of knowledge of Sketchup. Any ideas? Thanks

I'm no expert with Sketchup - in fact these T Copters are my first real play with 3D modelling at all. Several of the hundreds of hours I put into these designs was trying to work around Sketchup quirks. You may just need to try approaching what you are doing a different way. Sometimes I'd create a face (or shape) somewhere away from the model, group it, then move it into the correct place in the model so it cuts everything it needs to, explode it, Intersect faces with model on each face, and then delete the surplus bits. I'd still run into problems sometime when cutting though curves and Sketchup sometimes slightly moves/joins lines if they get to close to each other - especially on curves. "Show Hidden Geometry" seems to be useful to turn on occasionally so you can see the hidden lines that Sketchup uses to make curved faces. I've only been using the free version of Sketchup - you may have more tools available to you.

Better learn to work with solidworks. Sketchup build incomplete solids. and you have to repair them before printing.

I got a deformed arm, so now I'm printing with the raft. I also did a toucher test with my Tesla Model S wights about 5K pounds (2270 KG). 35% infill, 2 Shell and, .30mm layer height.


Love the video - although that arm might be a little worse for wear than it looks (given the crunching sound)!

That arm sure was deformed though. If you're using a heated bed then try turning the bed temp down a bit and perhaps try some other options to get better first layer adhesion (see posts below). I've never had to use a raft. Thanks again.

I don't have a heated bed. The best option for me is to go with the raft and the leveling some shifts overtime causing that deformation

Hi Brendan22, can you tell me the difference between the x8 arms and the regular arms. I don't see anything indicating the difference. I see int he pictures you use the regular arms. Thanks!

Check out the T6 to see the "coaxial" arms in action: http://www.thingiverse.com/thing:246350

T6 / Y6 hexacopter

Printing the body, it will take all night.
My motors have hole separation of 22mm, so I am remixing the arm to fit it.

Just finished up printing on PLA at 100% fill. It weighs in at 185g, how is that compared to other's? what is the lightest print that still gives good mechanical stifness with PLA?
I am still learning to fly so I crash more often than I would like to admit, so I was thining that I wanted the body to be as strong as possible. Unfortunately I had some curling during the print so I think I will have to print it again.
I also noticed that the inside of the octagonal arm sockets need supports, any chance of adding a couple of thin (0.4mm) walls in there? using the regular supports adds a lot of cleanup and I am not sure it can be cleaned well enough to allow for smooth insertion of the arms.

Personally I haven't experimented beyond the setting shown on the Instructions tab. The bridging in these designs is pretty minimal and most printers should handle them (without support) once properly calibrated. Perhaps experimenting with some bridge calibration objects (eg http://www.thingiverse.com/thing:12925 ) might help.

Bridge Torture Test

What size motors do I use for this drone?

Hi! I just printed the short legs but they don't click (or spring). The inner part where it's supposed to go in and out seems to stuck. Any ideas? This seems to be the problem: https://plus.google.com/u/0/114905597188247018535/posts/EfFnEnZoJAj?pid=6062242966992781010&oid=114905597188247018535 -- Btw I printed another one while rotating it 180 degrees on Y axis but it didn't work as well.

In the STL files there is about 0.3mm clearance between the moving plunger and the leg itself. Your printer may be pouring too much plastic into the part resulting in that clearance being reduced due to the extra plastic "squidging" across the gap. You could try reducing your extrusion multiplier (or whatever it is called in your slicing software).

Also, it may just be the first layer that has "squidged" enough to stick the moving parts together. You could try running a sharp blade down both sides of the plunger crack shown in your photo, Then try a good sharp push down on then bench - that might be enough to break the plunger free.

Which software do you use for slicing? ReplicatorG? I'm currently using Makerware.

Hi Brendan! Did you specified special configuration for the 3DR Pixhawk during your purchase? It has options for PPM encoder, digital airspeed sensor, external led and usb, telemetry radios and so on.. If you don't change the configuration it seems like the prices is ~$280..

As you can see from the links, all of this info is in the Wiki I linked to: http://copter.ardupilot.com/wiki/table-of-contents/

Btw do I have to buy Power Module when I buy both QBrain ESC and 3DR Pixhawk? I thought QBrain has the Power Module (BEC?) in it?

I've tried printing arms without any rafts but it fails everytime. It's pretty hard to remove the raft afterwards and the outcome is 55g's. Removing the raft makes it 50g's as it proposes in Makerware. I'm pretty new to this era, trying to learn. So any clues might be usefull. Thanks for this work btw! Really appreciated!

Are you using PLA or ABS?

I print with PLA into a heated (55 deg C) glass plate that has been sprayed with budget hairspray. It's also important to make sure that the first layer is just the right height - not just a "bead" but a little bit squashed - and that your bed is level. About every 5 prints I wash the glass off in warm water, make sure it is perfectly clean and dry, and then re-coat with hairspray (1 medium coat).

I've not had any problems with adhesion and have never used a raft.

ABS is a whole different story and I have very little experience with it.

I'm using PLA. But the surface (plate) is a slippery paper-ish kind of thing. In fact it's the 3d printer of a software company that I work for so it's being used for hobby projects. How do you heat your plate btw? And why are you spraying it? To make it less slippery maybe? I had to use a raft with T4ArmX8.stl as the edges started to lift from the plate causing the whole object move and therefore screw up the whole print.

My printer came with an electric heating element in the bed. Hairspray on glass is a trick to help the first layers stick well to the glass. It works really well and is almost impossible to pull the parts of the bed until it has cooled down ..and then they just pop right off.

Well I just learned that our plate has been changed for convenience. They stick a slippery paper on the plexiglass surface so that the objects can be removed easily. In my case, however, it caused lifting. I solved it by increasing temperature from 230 to 250 'C and used the plexiglass surface instead of the paper side. The result was perfect! :) I got an arm which has almost a flat bottom. I'm now printing the 4th one!

I really would appreciate a full how-to for newbies though. I'm planning to print every part I can then start to buy motors, GPS module, ESC etc... However I have no idea whether it works when everything is mounted or I need to do further balance (like mounting it into a computer and so on..) I'm still trying to understand the minimum parts I need in order to get it fly. It's pretty exciting though!

Yep, there is a lot to learn when you're starting out. I highly recommend the ArduCopter Wiki: http://copter.ardupilot.com/wiki/introduction/what-you-need/

Also, have you checked out the T4 Build overview video: https://www.youtube.com/watch?v=fcePiS2GGag

Yes, I've read and watched those. The video was helpfull more than anything so thanks! :) So it seems like we print the body, arms, legs and the stick of the GPS module, right? Then the rest of it should be bought. How about the cables? Do they come bundled with some part?

Yep the T4 body here is just the beginning. You can spend anywhere from $200 to $2,000+ on other bits to make it fly, cameras, FPV gear, etc...

Take a look for a Google docs link a few posts back for a list of some component options. Part of the fun is researching each part thoroughly to make sure it is compatible with the other components you pick. Some components will come with cables and some won't.

you have a mount for the sonar?

I don't have a sonar so I'm not sure what sort of mounting they require.

What printer are you using? I used your settings but my printing time come up much higher than yours. e.g. main body 14 hours

I would like to ask if there is any chance to have other part files then sketchup. I tried Sketchup but I can not work it out. I am using Solidworks. I just need to amend dimensions for end of the arm as my motors are 35 mm in diameter.
Or if I design it myself what difference should I make between internal dimensions of holes on the main body and outside dimensions of the arms?

...the arm sockets have 0.1mm clearance around the arms. If you draw yourself a 25mm square that would become the outside flats of the arm. The top/bottom faces are 11mm wide and the side faces are 5mm high. Based on that cut the corners with diagonals and that would be the outside arm profile done. The "wall thickess" of the arm is 2mm and the vertical beam inside the arm is also 2mm wide. Extrude that shape for as long as you want the arm and that's the basic "tube" bit done.

"times were recorded on my Makergear M2 printer which has a 0.35mm nozzle and was printing at 4500mm/min" ...as per the Instructions page :)

I've never used Solidworks and only have the files available from the free version of Sketchup Make sorry.

What do the electronics (options included, fully loaded) cost on this? Sorry if you've answered this but I didn't see it in the thread.


great design. could you advise me how to get rid of support as most of hollow spaces are filled. I have 3d touch by BFB.
Thank you

You'd need to contact BFB if you are using their software (Axon?) to slice the STL files ...or reach out to whoever you got your slicing software from. I use Simplify3D and there is a tick box in that to "Generate support?" (which I never tick).

Comments deleted.

Hey buddy, I think we decided to go with the T4 instead of the T4 mini due to space. I was wondering does this arm fit a 28mm motor? I need a 2mm gap so a 30mm cup for a t4 arm.

Yep, these arms are made for 28mm motors (actually just over 30mm inside the cup).

awesome thank you! We printed out the arm for the T4 but its way to big for our project. Is it possible to send us the editable files for the T mini 250/315? We are looking at enlarging the middle section of the T 4 mini 315 class arms as the same diameter as the Orinigal T4 arms. Just the middle section. Please do let me know thank you!

All of my designs should have the source skp (Sketchup) files already in the downloads. You can download Sketchup Make free from: http://www.sketchup.com/products/sketchup-make

I noticed that when you first install Sketup it will let you export to all the formats for the first 8 hours. After that it goes into "freeware" mode and limits the formats that you can export to.
If someone can manage to convert the files to .igs it would be great.

Hmmmm. Thanks for sharing.

after email banggood about the hovership, I managed to get them to take it off.....they sent me this email.....
reckon its worth emailing them.....good luck!!
Thanks for giving the information. I have contacted the manager and explained the situation and he said we will not sell this product anymore, I do not think we have sold any yet.
Thanks for contacting me and sorry for causing you any stress.
Please let me know if you have any further questions and I admire you for standing up for protecting your rights.
If you have other companies doing this I recommend you make a template of copyright infringement, usually a on or two page document that outlines how you own the design and the ascoiated copyright policy. And usually ask it to be removed immediately and if not removed within 7 days of this letter you will defend your copyright, something like this is quite effective.
It will look more formal and I think you will have a better response from whoever you send it to.
Thanks and I have informed the team to not take designs like this."

Looks like they lied to you. I just clicked that link and it is still on their site. I guess your design is just too nice for the to give up.

Another T4 completed....almost !

Is there any conflict with the 4x20A Q Brain and the 850 KV motors from 3DR you suggested? Going off the 20A rating of the Q Brain, the definition here of the ESC https://www.hobbyking.com/hobbyking/store/tips.asp?idtip=3https://www.hobbyking.com/hobb... and the info of the data sheet of the 850 KV http://3drobotics.com/wp-content/uploads/2013/11/A2830.pdfhttp://3drobotics.com/wp-conte..., seems like the ESC wouldnt be rated high enough. Thanks!

the esc is rated 20A per output and there are 4 outputs... that motor will pull about 4-5A with an 10x4.7 prop in a hover. it will be more than fine. I am using that same setup on my Iris and my hex.

Thanks, sorry if it was dumb, I was new to most of this so wanted to check.

no problem.. happy flying!

I figured you would like to see a video against the Iris. Very stable!! https://www.youtube.com/watch?v=b9C40VErCQchttps://www.youtube.com/watch?...

Cool video thank you! I have to admit I haven't flown my Iris for a long time now ;-)

My T4 is almost ready for a maiden flight, but how do you guys prevent the GPS pole from falling out?

Most of mine have been a firm fit. You could add a little hot-melt glue for piece of mind.

So I was able to print the arms and the main body.. both were way way way off the build platform when importing to makerware. but i found them and moved them.. so far all the other parts I cannot even find them.. tried importing to sketchup and same deal? any ideas.

Nevermind figured out in makerware how to center it and then rotate it.

FYI, I love the design. Even got myself a tarot gimbal.. here is a pic so far of 2 arms and the main body (whew!) main body was scary because whatever PLA i am using they wraped it real bad and it tangled.. 10 hour print for the body I was real lucky to happen to be in the general location when it got tangled.and paused it hah. picture http://ktmdirtface.smugmug.com/photos/i-wxfK4TK/0/X3/i-wxfK4TK-X3.jpghttp://ktmdirtface.smugmug.com... cant wait to get it done and fly it.

Great to hear you've got a T4 in progress. Those motors sound good. I'm not familiar with that flight controller sorry. Good luck bringing everything together! It would be excellent to see another one on the "Made" tab if you get time.

Just for an FYI, I believe I figured out some of my stability issues. I was using a 4s battery with the 850kV 3DR motors and 10x4.7 props. This setup is definitely over working my motors and ESCs. They get quite warm and makes the copter unresponsive and hard to tune. It is recommended to use 8in props with 4s batteries. I switched to a 3s battery and definitely like night and day the autotune went in perfect and now flys like a champ.

Awesome design. I'm trying to print an arm right now on my Makerbot Replicator 2. But the non motor end always warps and peels up. I'm trying to add a brim to it back there in sketchup but the scale has me messed up. I did manage to scale it down but its off waaay far away from the origin. Do you have any idea how to get sketchup to snap the camera to an object? so its in view..or move an object to the origin?

just saying on my end I print on an acrylic bed with painters tape and, yes, Sauve extreme hold hairspray ... I have not had warping issues since ... even on thinner wood filament projects ... light spray ... let it set ... print ... not sure if this is your issue but may help in future attempts (running on the same machine by the way) did my first two legs and no issues

From memory CTRL-SHIFT-E "zooms extents" so every thing in the drawing will fill the screen. I usually select and copy one part into a new file. Then select all, start scaling then then type 0.001 to scale exactly by 1/1000th, then zoom extents. If you want you can then "Move" the object closer to the origin.

Thanks I ended up copying a leg to a new file, scaling it copying it again to another new file lol.
I added my own brim to it ( maker ware doesn't seem to have that option ). Got a arm to print good. Have Turnigy 2836/9 950kv motors on the way. already have 30amp plush esc's and a Crius AIOP V2 board + GPS. Ordered a tarot gimbal should be cool!

Are there more people that can not fit their LiPo in fully? Because of the connectors that come out of the side it does not slide in all the way :(

What size or brand battery are you using? I run a 4s 4500mAh and it fits great.

I use turnigy 3S 5000Mah

Running with a zippy compact 5800 no problem. I couldn't get the Crossfire 2 stable with a battery this large but no problem at all now.

Are you just using the PIDs from the Iris setup? My drone is a bit twitchy.

Curious if anyone wants to share their kk2 settings. I am still tweaking but it's very stable so far.

Do you think you will create something to mount the mobius with the anti vibration balls to this?
I'll be upgrading to a pixhawk but I don't have any gopro fiunds yet :)

I might have a go at them sometime. Have you tried this camera plate with gel pads - http://www.thingiverse.com/thing:286257http://www.thingiverse.com/thi...

T4 accessory: universal camera plate

I don't have the gel pads and a ton of the anti vibration balls ;/
But I will print it out tonight and see how it fits.

I combined your sugestion with the go pro plate. Looks great. Will add it the picture. Thanks!

Where have u guys put the power distribution board?

I used a 4-in-1 ESC for the T4. For the T6 I made a nice compact one like this http://fangin.com/blog/2012/03/18/how-to-connect-4-escs-to-one-lipo-battery-make-a-power-distribution-board/http://fangin.com/blog/2012/03...
I haven't tried squashing a purchased PDB in the bottom tray myself - the tray may need to be made a bit taller to give enough space to fit with the ESCs?

I think I will go with the spider approach, there is enough space to fit my Afro 30A ESC's in there :)
Still need to print some parts, I think that by the end of the week most of the printing is done (with the green color) then a few orange parts still need to be printed :)

Not for FPV but have you used the Wifi capability on the GOPro to live stream?

No. I keep Wifi on the camera turned off ...especially when using 2.4Ghz for remote control.

Today is Body-print-day, check the progress through my livestream :)

Interesting color!

Does the GoPro fit snug for you or is there some double sided tape?

It was a snug fit for me.

Hey, just got my pixhawk installed and flying great. What mode are you using for your videos?

I tend to just fly in Stabilise. There is a new "Hybrid" mode coming in Arducopter version 3.2 that sounds like it is flying really well. It is a combination of Drift, Altitude hold and Loiter. I haven't been brave enough to try the current "daily master builds" at the moment as it is still very much in development but there should be a first release candidate out in the next week and hopefully a full 3.2 release in about a month.

I'm building this, have already printed the Quad, ordered the parts and receiver, all set next week, but...
Where is the best place to get small metric parts? I need M3 x 40, M3x 20, M3x 5mm, ect, and I can't seem to find a good place to get them. either you have to buy 50 online, or you have to buy each one separately for $2.
Help! .... and thanks!

I use boltdepot but they are expensive for shipping. You can always go to lowes and use non metric sizes close to what you need and drill out the holes a tiny bit.

My Ace Hardware always has the metric bolts I need. You may want to give that a shot if you have one nearby.

I will get some pics up soon. I started with your version of the Crossfire 2 which I couldn't get stable but this was smooth and solid right from the start! Thanks for the great work!
Will there be any modified versions with the front arms a bit more forward to fit different props?

I'll have a look sometime at a version to support larger props. The constraints include keeping the battery in the centre of thrust and the props out of camera shot. It would probably mean longer arms as well as different angles - in other words a complete redraw (although longer arms might do it - I'd need to recheck the geometry).

Not sure how much bigger the arms can be for my mendel90 20x20 but I think I have a little bit more space to go.

To keep within the print bed constraints it would need to become more of an "X" quad - but then you would loose the advantage of the "dead cat" wide prop spacing at the front so more chance of the props appearing in video. Perhaps the Tubular Crossfire design would suit you better.

Test Flew today. This thing is rock solid. Very stable. Body took 12hrs to print last night Hope to have some pics and videos up soon.

Awesome, it's great to hear your T4 is off the ground! If you get time I'd love to see a photo posted under the "Made" list.

Do you think you could make the landing gear like a split collar so if you brake it you do not have to remove the entire arm?

Your request has been granted :-) ...check out the split mounting option on the legs here: http://www.thingiverse.com/thing:313422http://www.thingiverse.com/thi...

T copter springy legs

Awesome! thanks

I've got some ideas for that but I'll need to do some testing - hopefully this coming weekend.

sounds good I was going to try it myself in sketchup but I am no drawer even the simple things.

Hi I can´t make a gcode Filde out of the Body with Slic3r?
I start generating and it works for about 3 hours now but that could not be right?
My Printbed is 200mm x 200mm should be good if i let skirt away or not?
What Can I do?

I'm not familiar with Slic3r sorry - I use Simplify3D. Perhaps it would be worth asking a question on the Slic3r support forums: http://forums.reprap.org/list.php?263http://forums.reprap.org/list..... It should only take a few seconds to slice the body.

I let Slic3r run with it and I think it easily took 5 hours which is crazy! It does work be cause I used the gcode that slic3r created to print the body on my Mendel90.

Simplify3D slices the body in a few (<5) seconds. Can anyone else using Slic3r make any suggestions?

I had problems with the latest version of slicer. It seems to hang on Large items. It was able to slice everything but the main body. I downgraded to an older version and it worked fine. I am know keeping 2 versions of slicer on my computer.

I have been printing this project with ABS so far no warp issue. ABS slurry is working like it always does. Any experience with the Multiwii Pro flight controller for this build?

Thanks for the reporting your success with ABS. I personally don't have any experience with the Multiwii sorry.

FYI, for settings. I am doing 2 shells 50% infill at 75/100

I've got a question about weight, and specifically how much the extra 150g of plastic I used (extra shells) will affect the performance. Do I need to print again?

The thrust available to lift your T4 will depend on the motors, props, and battery voltage you choose. I have flown my T4 carrying a 6,000mah battery, Tarot gimbal and GoPro camera which adds up to about 500g more than flying with just a 3,000mah battery ...and it flew fine. Ideally you want it to hover at somewhere between 40 and 60% throttle. I expect you'll be fine - give it a try :-)

Finally had a chance to finish the build I started. Really nice quad! Flies beautifully with RCTimer HP2212-1000kV motors, GemFan 10x4.5 props, HobbyWing Quattro 4x25A ESC, an APM 2.6 w/GPS+Compass, and 3300kV 3S battery. Hovers at just under half throttle.

Impressive build now that I've seen it fly!

Bravo Brendan22!

Thanks Zebble - great news! Comments like yours are the reason I love sharing my projects!

I'm having this printed right now thanks to another Thingiverse member who is local to me. Do you have any build instructions or photos that you can share. Maybe a hardware list (x number of this screw, that bolt, etc. I'd also like to hear what electronics that you'd recommend using for optimal results.



is there a way to make the model smaller, this will not fit in my print bed, I have a 200x200 print area and I cannot print this, do you ahve source files so we can resize, I need to make the arms smaller, (not too much, and the body smaller. Thanks

Excellent to hear you'd like to print this. The biggest part is the body which should measure 199mm long (half way up the maximum bulge at the front - or 195mm on the first layer) and 140mm wide. The arms should also fit easily if you rotate them by 45 degrees. What dimensions are you seeing? I guess your slicer might complain if you were trying to print a skirt around the body?

Oh ...and the there are several Sketchup CAD files attached (T4_1_04_1.skp is the latest at this time) if you do want to make any changes.

Now my printer is all set, I am working on planning this print.
I hope that I can fit it on my building platform, might need to tweak my printer a bit to make it fit or change the design a bit :)

So it seems that I need to edit the design a little.
It is not gonna fit :(

Darn. I had a quick search for Prusa i3 build volume and it sounds like it is about a 150mm (6") cube. Does that sound about right?

I'd be really impressed if you can shorten the T4 body down that much and keep the same motor spacing (to fit 10" props). It took a couple of pretty significant trimming sessions to get it down to 200mm x 140mm (8" by ~5.5") to fit some other printers. If you got really brutal you could chop about 30mm off the back end (and let the battery hang out the back) but to get 50mm there wouldn't be much (anything?) left supporting the back arms and you'd be starting to cut into where the flight controller is mounted.

Sorry I don't have anything more helpful than that. I do have a medium term plan to design a T4 mini when I get my hands on some smaller motors.

The hardware that I will be using:
4 X Afro ESC 30Amp Multi-rotor Motor Speed Controller (with Simon K)
4 X Turnigy Multistar 2213-980Kv
APM 2.5
FPV Gear

So it seems that I have found a way so I can print this copter :)
Now I need to get some nice colors so I will have a nice quad :D

ok :)
I will see if I can work something out.
Will give it a try tonight :)

I am really interested in building this design however I do not have a 3D printer. Anyone out there willing to print it for me (I am located in northern virginia) and have any idea what that would cost? Cheers.


Jerry, great shoot me an email so we can work out the details please. Cheers. Kris

There's around $25 worth of plastic in the T4 ...and 20+ hours of printing time. I tried uploading just the "body" part to Shapeways but they wanted $144 just for that one part. I hope you can find someone local to print this for you - I'm sure you'd like it ;-)

Really neat design Brendan! Thanks for sharing.
I have been printing the parts all day. It prints nicely. I also ordered the controls, motors,.., from 3D Robotics tonight. I have a lot of experience with electronics and controls but am a total newbee at RC stuff. I finally decided the only way to swim was to jump in.
I want video on it and don't know much about that either. Which model camera gimble do you show in one of the videos? Do you link the video down for live view and if so, what do you use?
Which forums are best for getting into the multi rotors?

Hi tmac - great to hear you are making one of these!

The gimbal I use is a "Tarot T-2D" (search for that) with a GoPro Hero3+ silver. You'll also want a "GoPro hero 3 video cable" which you can use to connect to a video transmitter. Speaking of video gear I use either ImmersionRC 5.8Ghz gear (nice and compact - see GoPro on top video) or 1.2Ghz Lawmate gear (longer range but bigger/more awkward - see gimbal video).

On the receiver end I use Fatshark goggles for the 5.8Ghz or a small LCD screen for the 1.2Ghz (but these can be mixed/matched with some extra cables). The SpiroNet/mushroom/bluebeam style antennae are well worth it. If you're using a 3DR autopilot then the minimosd OSD can overlay useful info on your video display.

That's just me - there are PLENTY of options! Forums such as http://DIYDrones.comDIYDrones.com and http://rcgroups.comrcgroups.com are great and http://copter.ardupilot.comcopter.ardupilot.com has about a weeks worth of very useful reading (click Table of Contents).

You'll have great fun - but the possibilities are endless and a lot of this stuff is still very much "under development" so expect the occasional frustration too ...and buy a few spares :-).

Is the new (march 14) Body file compatible with the previous top and bottom? I have Printed them but not the body yet?

Unfortunately not. There have been three revisions to the basic shape which all affect the body, top plate, and bottom tray. Do you have a download of the body.stl to match your other prints? If not, let me know which version you have and I'll see if I can sort out a matching one.

Thanks, I have the complete folder from the previous version. Will continue on with it for now.

Hi there, I have a Replicator 2 and when I try loading the file, it asks me to resize, however if I say don't resize the object seems to disappear and can't resize it myself or interact with the object at all... can anyone help me please?

Thank you kindly

According to Wikipedia apparently "there is no scale information [in STL files], and the units are arbitrary". A quick search showed that there is often confusion with STL files and metric versus imperial (inches) units.

I designed these parts in Sketchup using metric units and I believe the STL files are also in metric units - they size correctly in my slicer which is set to metric. Perhaps your program also has a way to select metric units or scale down by a factor of 25.4?

Thanks for the reply, I actually found out what's wrong with it.... the parts are not centered, so when I open them with Makerware, they show up like a meter away from the print bed. But I managed to not resize them and now am able to print. Thanks a lot! Will post pics when I finish!

Ah ha. Thanks for the update. I'll make a point of moving the part closer to the origin when I create the STLs from Sketchup. I'm not sure that will help ...but it might.

Nah just post a note to those using a Makerbot/Replicator to not resize the object, and just look for it a few meters away from the printing bed

Thanks. I added a note to the bottom of the instructions (crediting yourself).

Great!!! I am making one :-) Hope it will work ok with 920KV motors and APM 2.5 fc.
Can I ask for specifications on the 6000mah battery you use which fits inside?
I hope to get a front mounted Gimbal fitting, like this perhaps:

Kestrel GoPro Stabilisation Gimbal Hero 1 and 3 versions
by markab

Hmm my last reply seems to have been deleted. Anyway, great news that you're making one of these! The 920kv motors should be fine as long as they fit the cups (31mm internal) and have a pair of 19mm mounting holes. The APM 2.5 would be perfect. The 3S 6000mah battery I'm using is a Turnigy nano-tech. The latest body and top plate has 3 mounting holes on the "nose" which I hope would be useful for mounting things such as the gimbal you linked to.

The motors are DJI 2212/920KV, Dimension : 28X24mm so they should be ok (harvested from F450).
Looking forward to getting it printed. I am selecting colours, and getting some parts. Will post pictures!

DJI motors, along with a lot of others, have a different but standard 16/19mm bolt pattern. Had to rejig the arms with this bolt pattern. Seems to work well.

Most of my motors here have got a 16/19mm pattern - but they are not consistent with which corner the wires come out. To enable all of these motors to point their wires directly down the arm I made the arm with a 19/19mm pattern and only use two bolts to secure the motors. Using 2 bolts to secure the motors seems to be the normal practice (all of my 3DR purchased copters only use 2). Did the 19/19mm pattern not give you an option for the DJI motors - or did you just rejig the arms to enable 4 bolts?

Interesting... I've always used 4 bolts, including on DJI frames. Never thought of using 2, but would definitely make things simpler!
The rejigged 16/19mm pattern worked perfectly for the DJI motors, and with some RCTimer HP2212-1000kv's. They both seemed to have the same pattern and wire position.

You could scale this down by 15% but you'd probably need to do some work on Sketchup to fix up a few bits. In particular some dimensions are made to fit real things. Some examples off the top of my head:

  • the 3mm bolt holes would no longer be 3mm
  • The motor "cup" at the end of the arms is made to fit a 28mm motor can (cup is 31mm internal diameter) and the hole spacing for mounting the motors is 19mm. You'd need to tweak those for whatever motors you'd use.
  • The flight controller mount (and switch hole if you use a Pixhawk) would need some adjustment.
  • You'd need to test to make sure that your motors wires (with bullet connectors) could still fit through the arms.
  • You'd probably need to use smaller propellers.

If you do draw up a smaller version, please post it on Thingiverse for everybody to use.

I have a question! Could i print all files for the quadcopter 15% smaller? I dont need my copter that big.

Can you post the original dimensions, mainly the arm and body length/width? Thx looks great!

Arm "envelope" is just under 216mm long and 36mm wide.
maximum Body "envelope" is 199mm long and 140mm wide.
The Sketchup file is zoomed x1000 so if you want to recreate any STLs you'll need to select the relevant components and shrink them x0.001

How much PLA is required for a print?

About 450g (or half a 1kg spool)

Great frame, I may have to print this if I can make it fir my printer
Do you print it in PLA or ABS?

I printed this in PLA.

I presume there would be no gotchas if I printed this in ABS (its the only filament I have/use). Or was there a particular reason for PLA?

I've had feedback from folks having trouble with ABS curling and not sticking to the bed when printing the thicker parts (e.g. arms and body). Perhaps try an arm first. If you do have success please let everyone know (and perhaps provide some advice on your temperatures and methods to help others). PLA is hassle-free :-)

OK will do, thanks for the quick reply. I've got to sort out a small problem with my heat bed and will give a single arm a go and report back the results.

Nice quad, also very cool that is so tidy on the outside.
I also would like to see a version that will fit a normal 200mm printbed.
Still learning with the drawing bit of 3D printing, so if someone could create a smaller version I would really appreciate it :)

That seems to be a popular request! Okay, I've taken another look at it and found a way to get the overall length down under 200mm. Stay tuned - I'll work on it over the next day or two.

Smaller version is now posted.

Cool, thank you :D :D

This is great! Unfortunately it is about 23mm too long to fit on my print bed. Any chance of making it a little shorter?

I've had a rethink about making this shorter and have a plan - stay tuned :-)

that's great! I started looking at the sketchup file, but I have never used that CAD program and didn't see an obvious way to edit the file.

200mm is a pretty typical max bed size, so I am sure you would make a lot of people happy with that change! :)

Shorter is a problem as it is mostly constrained by the location of the props, the length of the battery compartment and the center of gravity. The front and rear props are already only about 10mm from touching (similar to the 3DR Iris) and I really want to try and retain the battery capacity. That said, if you removed the rounded front all-together you'd gain about 18mm and then cutting the back off straight across the vertical posts would save about another 4mm so you might just squeeze in. I'm not in a hurry to do a chopped version just yet though. You are welcome to have a go at the Sketchup file yourself - but please post your result for others to use too.

Not that it helps but I have just about finished a slightly narrower version which cut the width requirement down to 140mm.