Edit: You should consider
using this newer version instead.
(which doesn't require to reverse the stepper motor's wires anymore.)
BEWARE: With this design, the motor is inverted. So, you have to revert the plug, or adjust the settings in your firmware (see below, or use this extruder).
Here is my custom extruder feeder.
I spend days on the design (thanks to my computer crashs...) and print several prototypes to obtain what I wanted:
- Something usable with any 1.75 filaments, including flexible ones
- A discreet design (not "cheap" as the default is)
- With a place to put a better runout sensor switch
- Including a cover to protect the motor axis from dusts
- Easily openable to see the inside for maintenance
There are 3 main parts + 4 small ones, I've included a STL file with all-in-one if you don't want to manage different settings for them.
You will have to re-use the spring and the ball bearing from your default extruder feeder + its 4 screws. The only thing you will have to add (but you could use something else...) is the runout sensor switch + a plug where you can put the default runout cable (or you can weld directly if you prefer). I suggest to use thin wires as I've let space for it.
I'm using this kind of microswitch:
(you can find all dimensions in the FreeCAD file if you want to check)
I personally printed it at 0.2 on my U30 with an old and cheap black filament, with supports activated. You will probably have to spend a bit of time with a precision knife to remove printing defects + sand a bit some parts. Tip: Cut a thin strip of sanding paper, roll it to get like a small tube, put in in the hole for the filament and clean it with this "tool".
FreeCAD: Please note I'm a beginner on FreeCAD (about 1 month on it), and my computer is very old (2009 !), so the source FCStd file is not perfect and heavy: I had to make more sketches than necessary because sometimes I cannot edit other ones without my computer crash... Feel free to clean the file and send me a better version.
Remixes: I share all my designs with the default license, so you can modify what you want. But I will really appreciate you mention the original design if you do it. ;)
If you like this piece, share it and leave a comment.
If you can't change the direction directly in your firmware, you can easily reverse the direction of your extruder motor by change pins order in the cable plug connector (I will explain for U20 / U30, but I suppose this is the same with other printers).
There are 4 wires in the connector, put in a 6 spaces plug: Let's call them ABCDEF. B and E should be not connected, so we will ignore them. Put A into F, F into A, C into D and D into C. That's all!