May 12th, 2019
Added some print tests pictures
Upcoming V2 : Toolchanger
E3D (that's the guys who designed the 'original' machine - i think they released it now, or it will be soon) reported that the servo of their beta printers was failing after 60k changes, so they switched to a micro stepper. I will follow their research/work and redesign my toolchanger to use micro-stepper too.
After some tests, i'll use a 24BYJ48S 2-phase mini-stepper, smaller ones need too much gearing, thus tool changing speed is reduced, and when it's 4 changes per layer it's a huge win to go as fast as possible.
Steppers have drawbacks too. At the moment i don't see how to use a stepper without some kind of endstop, and without risks of position loss at power down. It would be nice to do it the software way on the duet :) - servos are absolute positioning systems so i did not have the problem before.
Alternatives for the lock-system :
- a 24V electromagnet (abou20mm x 15mm, 28 grams and 2kg hold) : theorically the best solution regarding locking speed, but very hard to implement combined to a spring-loaded system. Spring-loading is imho almost mandatory to account for errors coming from parts machining, tool-garage position, etc.
- maybe a cable-driven remote system
In the v2 the kinematic coupling balls arrangement will be a lot more optimized than just 3 holes in an equilateral triangle shape. I also reversed the triangle (it's now 2 balls on top and one ball at the bottom of the toolchanging system).
Upcoming V2 : Motion
I've always been mitigated about coreXY
I'm still. So now that the work on v2 has begun, i made compared 3 XY motion systems, considering every tiny moving mass of each, including belts, pulleys, screws, etc :
- CoreXY as in the v1 funX4
- mgn-based ultimaker-style XY
- and a simple XY gantry with a light moving X-motor.
Surprise :) a simple XY with moving X motor is not even heavier than both the other solutions. So i'll go for it.
Because belts, and a lot of other things.
In the quest of the lightest possible X motor i thought back about oDrive (a friend of mine has one).
Experimental but so promising.
So v2 will have an oDrive-driven brushless-powered XY gantry :) Whether it's with belts or with leadscrews
If it's as good as it looks, a leadscrew driven XY could work at the same speeds/accelerations as reached today with the stepper/belts system. But that's a lot, lot, lot of tests to get that working (super fast vibration-less leadscrew rotation is really not so easy to achieve)
No modification to the Z, it works nicely
Upcoming V2 : Part cooling
It's all about PLA... every other material do print fine, but PLA needs more airflow so the design needs to be changed to account for that.
Upcoming V2 : Multi-color printing speed
I did not make that much multi-color tests. I really like to be able to change head so fast, but in-print it's different. It works, but it's not comfortable, neither is it fast.
So to make it really usable, one needs to avoid two super slow things :
- prime pillar
- ooze shield
That's the purpose of the toolchanger.
So a filament priming trashbin and nozzle cleaner will be included from the ground up in v2's design.
I'm also working on a small gcode refactoring tool that will allow to edit files outputed by Simplify 3D, in order to add pre-heating management while multi-color printing. It will also manage different acceleration settings for printing moves and other moves.
Some details about the tool changing head
Tool changing head is divided into 2 "subsystems" :
1st subsystem - positioning mechanism
- it's a kinematic coupling implementation (ie 6DOF lock system)
- it's made with 3x 6mm diameter steel balls sitting in 3 pairs of 5mm diameter steel pins, epoxy (metal araldite) glued to the machined aluminium plates
- the repeatability of positioning accuracy is way above what i expected (can't even measure a difference with the tools i have)
- to ensure it's consistent across the tool-holder and the 4 tools it's mounted as follow : glue 3 balls to the first tool plate, then glue the 6 pins to the tool-holder plate and use the first (dried) tool to press the tool-holder while pins glue is setting-up. Then use the tool-holder and the same process to glue the balls of the 3 remaining tools.
2nd subsystem - servo-lock mechanism
- it's basically a spring-loaded T-shaped shaft
- the shaft is rotated 90° by the servo to hold/release a tool
- in locked position, the top bar of the T rests on 4 small steel balls
Why complicated steel balls and pins and glue and not printed parts ?
Steel is used for every part that contacts/slides often, to avoid wear. But aluminium is needed to keep it lightweight, that's the reason why it's mostly steel balls and pins glued to aluminium plates.
I'll test glass fiber reinforced filament and see if it can replace machined aluminium plates.
Afaik precision steel balls and pins are also the very cheapest super-precision machined parts one can find.
Caution ! Read this if you plan to build it
Please take extra (super extra) care when glueing the balls, especially the 6mm balls. You absolutely need to glue them with good 2 parts epoxy (araldite metal works really nice) and to not put too much glue. If there is too much glue you will have absolutely no way neither to remove the ball, neither to get it going all the way down.
for this reason i really recommend to (very gently) create two notches in each 6mm hole edge of each toolplate with a very tiny file.
this is enough to help the excessive glue to escape, and is really needed.
First Post :
Toolchanging 3d printer, similar design to e3d's.
First tests here :
Still work in progress :
- there will be modifications to the design ;
- this is NOT a "order, receive, mount and play" machine, keep it in mind if you decide to build it.
I'm releasing this now even if not definitive because people asked for it, but it's still a prototype.
I'll keep posting updates when i will do some.
Feel free to ask any details in the comments, i know there's not that much informations about the BOM in my files.
Duet Wifi + Duex 5 boards.
MGN15 hiwin rails for Z, MGN9 hiwin rails for XY
Openbuilds C-Beams + laser-cut aluminium plates frame
4x titan extruder
4x e3d v6 with threaded heatsink, pt100 sensors and precision cartridges
0.9° steppers, (1.8° for Z, with a 20T/40T pulley system)
PrintBite build surface
MKS DS450 servo
240V heatbed with panasonic SSR
Shoulder screws on every pulley
As people kindly asked, i activated the tip link so you can tip if you like the work. Though it's not mandatory at all of course, i'll keep working on it, even if it's not a very fast release cycle :)
I can provide the machined parts, just PM me if needed. Keep in mind that :
- even if functional it's still a prototype
- it's expansive and absolutely not a plug'n'play kit
- i'm not a shop :)