Drop in replacement for the ultimaker extruder big wheel/gear
Description
This is just a use of LeemonBaird nice library with added holes (esp. the big nut slot in the center).
Licence = CC BY-NC 2.0
Instructions
Just add a flat washer, a spring washer and a butterfly nut and you have a very clean and robust setup.
Update: it is now 6+ month old and it has less play, less wear and less wobble than the stock plywood gear that I used for one month or so! I added a picture for you to check (it is the one with the butterfly nut on)
Update: I uploaded a new set of files (namely wheel2.scad and wheel2.stl, wheel2_internals.jpg). These are 0.5mm thicker (to make sure the captive nut may not protrude from the wheel, so the latter cannot wobble when secured tightly). I also moved the small holes outwards slightly. Now, with a 0.4 mm nozzle and 2.0mm wall thickness, these holes really touch each other, and it makes the part more robust. See the closeup picture to get the idea (wt=1.6mm, a bit too low for the next layers).
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I think one of these with holes replaced with batsymbols would be a great addition to the batman endcaps I uploaded. Batman themed ultimaker, anyone?
Being under experienced at using the mouse and 3000 deep menus in CAD programs to draw I am always a fan of openscad where possible :)
Agreed! I cannot think of something less suited to hand-drawing than Openscad But hey, I do not want a hand-drawn big extruder wheel, so everything is fine so far :-D
In fact I really want to be able to fine-tune the objects afterwards (numerically) or to re-use/extend them, and a lot of the existing modelers make this difficult imho.
Openscad is really tiny compared to such clickoplants, it has a zero learning curve (but for the weird variable handling), and
it is perfectly suited to programmer minds (as long as you can pre-visualize any object as pure additions and subtractions of basic shapes and some more impressive operations like convex hulls or minkowski sums).
I would love to hack a few more features though, such as a real C language support (e
.g. for weird recursive stuff), metric tick marks on the axes, an "x-ray" view in 3D... oh come on, I made a 3D printer to print, not to code, we'll get back at this later :-)
License

This wheel has a different number of teeth (more) than the standard Ultimaker wheel, so I understand that it would result in a slower extrusion rate? Isn't this really a problem?
I just checked again, but I do find the same number of teeth. I superimposed both gears and they really match: this gear has the same geometric properties as the stock plywood gear, except for the shape of each tooth (which is better IMHO because it matches better that of the small delrin motor gear).
Now & FYI, if ever you don't have the same number of teeth on a gear, you have to adjust the "E steps" aka "steps per millimeter" of the feeder/extruder. It is quite simple in fact, and this is a calibration I recommend anyway when you try a new filament.