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All New Spring Loaded Bowden Extruder

by adrianm1972 Sep 5, 2017
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I am very confused. In the video you comment about how you made the thing 16mm thick and therefore a 15mm screw goes almost all the way through it but after I printed mine it comes in at 14.65mm and it seems to have printed perfectly. Thinking it must be on my end I have measured the STL file in every way that I can and I actually get right around 14.65mm... If I put 15mm long screws through, obviously they are going to stick out the bottom. I can use smaller screws, it's not a problem and that's not the issue. I just want to know what's going on here.

Think you gave some bad info,this should be printed in PETG and NOT in PLA...PETG is much stronger and has NO flex compared to PLA plus PLA is very brittle where PETG is not...About to print mine with SunLu PETG+ and I promise you it will not break,using 240/75 to print and with 50% with 1.6mm infil pattern spacing it will not break.Whatever PETG you are using must be cheap garbage and not actual premium PETG...Will upload pics under makes when it's done so you can see.

Hi Adrian,
What gear are you using to push the filament with? I couldn't find any reference to it in the list of parts needed.
Thanks for your reply.

Sorry about that. Its an MK7 extruder gear. I added that detail to the parts list and also added a link to my assembly video.

Does anyone have a link to the hob gear that works with this. I have a normal MK7 hob-style gear and its not working.

I am using an MK7. Not sure what's going on with yours. Please see pics and assembly video.

Hello Adrian,
Thanks again for all your great designs and videos.
I was just wondering if there is any news on your gear drive extruder?

It's an MK7 Extruder gear.

I was wondering if there was another size of bearing that would work as where I live it will take over a month to get here and there are very expensive.

That is very surprising 608ZZ bearings are used in fidget spinners, skateboards, roller skates and inline skates. They should be very easy to get all over the world and very, very inexpensive. I can buy 10 bearings for $5.49


I am working on a new version of this that is more compact and it uses smaller bearings. I am using another very common bearing but I would think those smaller bearings would be more expensive and harder to find.

First off,
Wow, I didn't know that they were used in fidget spinners and skate boards (thank you for the link btw). Secondly I already ordered two of those bearings from here
and what size bearing were you thinking of using for your new extruder setup?

To follow up on my original comment, they are just very hard to find in eastern Ontario as most of the sellers on amazon won't ship to Canada.

I finally printed/installed this... This extruder is nifty!

The adjustable spring tension is nice and everything fed and worked great.

The hole for the shoulder on the stepper motor was undersized in my case, I had to take a large drill bit and ream away some material.

I did find at my print speeds (80mm/s infill), a MK7 hob-style drive gear didn't cut the mustard whatsoever, so I'm going to re-install the full-toothed mk7 size gear that was working on my Bulldog clone (held enough that I could miss stepper steps) and re-test.

If I get a minute, I'll post a remix for 3030, which is to say just use the stepper base plate without the other part, and adjust the holes 5mm away from the stepper. For now I just drilled a fresh hole 5mm up and in the center after I printed the part.

update, the toothed driver gear was the fix.

I do want to impart one more item of wisdom - DON'T over tension! I had an issue where I was skipping too many steps, turns out I had to back out the tension by about 3-4 turns, and all was well.

Did you make a 3030 remix yet? if not... can an internet stranger kindly ask you to do it?

I gave it a shot and printing it right now to see if it fits. I added 5mm on the mount. Will post if it works.

I think your BOM has an error. It says '1 M5 x 30mm button head screw' but it should be '1xM3 30mm and 1x M5 10mm'

Hello Adrian!
Thanks a lot for all your great designs and videos.
I was thinking about switching to your extruder and was wondering if you are still using it and how it is performing.
Also, do you think that it is better to print it with ABS or PLA?
Any advice is greatly appreciated.
Thanks again.

I think it works as well or better than most direct drivre extruders. Its super easy to load and unload filament and it drives the filament very securely. It's only weakness is that it is direct drive. If you want to print really fast all direct drive extruders struggle with having enough torque to really push the necessary volume of filament. I think when I was testing I started having problems around 75mm/s with a real E3D V6 hotend.

Now I run a Bondtech BMG extruder with the same NEMA 17 36mm tall motor and with a real E3D Volcano I am printing at 80mm/s with the same level of quality as I used to have at at 40/mm/s. The BMG is a little expensive but it is flawless.

I am working on a diy gear drive extruder that anyone can build with gears, shafts and bearings commonly available on Amazon....stay tuned!

Thanks a lot for your quick reply!
I never print over 50mm/s so the speed is not a problem. Would your extruder perform well on a standard Hypercube by Tech2c or will it struggle with Bowden or should I wait for your gear drive extruder?
I am using currently "Belted_Extruder_v.3_for_1.75_extended by arturslab". It works good but it is very bulky.

It will work on a hypercube or any other 3D printer. This is a bowden tube only extruder.

I would wait a few days. Talking to you made me look at this again and I am working on an updated version that uses a smaller bearing and is even less bulky.

I will wait.
One of these days I should run to Tampa and buy you lunch!

This looks promising. What is the maximum length of the stepper motor, before it impinges on the belts on the hypercube?

You can use NEMA 17 motors up to 42mm tall without hitting the belts. You can also remix the mount and turn the whole thing 90 degrees.

Please print this out of PLA or ABS. We have found PETG is too flexible and it just doesn't work.

Thanks for the Info!

Hello, how do you attach the stepper plate to the frame spacer ? I printed it and there are 2 holes, do you screw directly in the holes ?
Could you make a design with nuts that you insert from the side ?
Also for the screw that is holding the 608 bearing, how do you thread it to the arm ?

Both are designed to self tap with M5x10mm screws. If your printer is calibrated properly the hole sizes should be perfect and tighten up very firmly. I know everyone loves captured nuts but they really are unnecessary unless you are constantly taking stuff apart and putting it back together.

I have had this extruder on my printer for around a week now and it's getting a workout. It is holding up well

Hi... first of all, thanks for the design, I think it's really great. If not too much trouble, can you provide the one with an M6 thread bowden tube fitting? Or maybe if you don't mind, can I ask for the .step file for the arm only, so I can re-edited myself. I have abundant M6 push fit laying around. Thank you

Sorry for the delay, .step file added to Thing Files.

HI Adrianm,
Could you please share me the older design or stl files as i don't have the 605zz bearing's. I do have some 608 bearings. Already I had build your old design works flawlessly but i missed the older files. Could you please help to share older files too.

No problem, thank you very much for the step file, much appreciated :)
Here's a remix for those requires M6 push fit connector, and added another arm for those who use MK8 gear https://www.thingiverse.com/thing:2549339

New Spring Loaded Bowden Arm for M6 push fit