R4G Extruder for Prusa, a DIY Bondtech Upgrade / Geared Extruder

by Greg191134 May 31, 2019
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Would you be able to make a version that will fit the Bear X axis? I think just the belt slots need to be moved slightly. There's already versions for both the Bondtech (https://www.thingiverse.com/thing:3477926) and the stock R4 (https://www.thingiverse.com/thing:3535905) extruders for reference.

Bear X Carriage for Bondtech Prusa Upgrade Extruder
Prusa MK3s Extruder Carriage for Bear X-axis

Are there any news about a bear version?
This extruder looks so good that I would downgrade my bear x-axis to stock :X

Hey Greg! Love the design, i'm getting great prints with this upgrade and the x carriage feels significantly lighter than before. I just have a slight issue with loading and unloading filament after changing the e steps to 830 (might be what codiac2600 mentioned). It goes into a continuous loop until I cut the power or reset it. I was wondering, have you figured out the fix for this? Thanks!

Glad to hear it is working well for you

I did not had this issue but since it's a 3:1 geared down extruder to achieve the same speed motor must rotate 3x times faster. At some point you hit the board/firmware limit.

By default maximum feed rate for extruder is 120 mm/s, if I remember correctly. Try to limit it to 1/3 so 40 mm/s with "M203 E40" and tell us if this fix the issue. If it's okay save with M500

Comments deleted.

I finally got the chance to set the feed rate and it fixed the issues I've been having. Thanks again Greg! Also, I would like to ask, do you use any custom firmware for your printer? Or do you use the stock firmware provided by Prusa?

Thanks for the feedback, I have added this recommendation to the description. I use stock firmware. I adjusted max feedrate in the past for another reason and did not remember about that change.

No worries, Ive always been a bit afraid to try a different extruder design but this one does not require a lot of money and is quite easy to assemble. I did want to point out that I did make a small change to the design from a potential issue that exists in the original R4 design. There is a forum on Prusa website that talks about the potential issues of tolerance on the bottom of the heatsink being looser on the R4 design giving it about 0.4mm more wiggle room than the R3 design (https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-hardware-firmware-and-software-help/the-current-mk3s-extruder-body-is-0.4-mm-loose-r/). I simply just made the diameter to 22.4mm to give it a tighter fit like OP's design on the forum.

Do you mind uploading the adjusted file? Thanks!

Sure, I'll either post a remix or send it to you tonight when I'm free. But its an easy modification if you got fusion 360.

I do, but man am I awful at CAD. Thanks!

Alright, here are the files for tighter tolerances of the extruder.

Thanks so much, I'm about to print it with Priline Carbon Fill Polycarbonate

No worries, I'll send it when I'm off work.

Good point, thank you !

Would you be able to make a version that fits the bltouch?

First of all thank you for this amazing design.
Any chance you can make a version for mosquito hot end ?

Thanks !
TheLightSpeed is working on a remix for the mosquito hotend. I'm not sure about the current progress but you can find it here : https://www.thingiverse.com/thing:3668800

Prusa MK3s Bondtech Extruder w/Mosquito Solid Mount & Filament Sensor

Also a question, is only advantage of using the pancake motor is the weight ? I don`t wanna buy new motor is it a big issue ?

To fit the Bondtech gears you need to move the stepper motor about 12-14mm away (if I remember correctly) from the x-axis rods. So mechanically this is not ideal because you increase the overturning moment on the rods that support the extruder. Using a pancake allows to mitigate that.

However you can perfectly test the design with the stock motor and if you are satisfied, later invest in a pancake.

MK3s can't handle 830 esteps with linear advance. You'll need custom firmware or it'll click due to the LA 1.0 not respecting firmware limitations of jerk and acceleration.

Eh? The same would be applying to the Skelestruder and I've got no complaints. Just changed the e-steps to 960 and that was it. Can you elaborate?

It's a known bug with prusa firmware and LA 1.0. Even skelestruder prints better with the community firmware and lowering e steps. The einsy cannot handle 800 plus esteps without skipping steps. Basically you'll print better at lower esteps and the community LA1.5 firmware.

Thanks for letting me know. I've not printed a lot after changing from FW3.5.1 to FW3.7.1. Maybe that's why I never noticed?!

Good to know Chris, shall I advise MK3(S) users to include M350 E16, M92 E415 in their startup gcode?

Stock prusa firmware doesn't have m350. The new 3.7.2 beta does.

Is that carriage for the stock x axis?

Yes, it's made for the stock x axis

I am super stoked to do this. I have thought that most of the other geared extruder designs have been too complicated.

This is very good work! Well done!

I just bought the Bondtech parts. I’m going to try to modify this for the Mosquito mounting.

I've now included the Fusion 360 assembly f3z file to make this easier

You are a champ! Thanks, that is very helpful!

Greg how hard would it be to add in the ability to add a Mosquito? With the square mount so it don't turn in the collar clamp? I am not talented enough.