NEMA17 press-fit Pulley Extractor

Press-fit pulleys, as applied on the Creality Ender 3, can be really annoying if you want to tweak your printer by installing stepper dampers, pulleys with less teeth, etc.

The latter was the reason why I needed to remove the press-fit pulleys on my Ender 3.
After looking around for a working pulley extractor design and trying out pretty much all of them, I figures that in my particular case, the pulleys where sitting extremely tight, leading to mechanical failure of the extractors due to miss-alignment of the screw which pushes on the stepper shaft. This miss-alignment mostly resulted from turning the screw while pushing on the shaft, which threw it off center.

I concluded that the alignment needs to be perfect to prevent mechanical failure of the extractor and to guarantee a smooth extraction. Therefore, I designed my extractor from scratch to include a guide that prevents any miss-alignment.

What you'll need is:
2 x M5 washers
2 x M5x4 nuts
1 x M5 x 30 to 40 screw
4 x M3 x 6 to 8 screws

How the extraction works:
1) Slip the extractor runner onto the shaft of the stepper motor (the thickness of the extractor runner is 5mm and should work for any Creality stepper)
2) Hand tighten the M5 screw while making sure that the screw is well centered on the stepper shaft.
3) Slide the guide on top of the extractor runner (Note: The design tolerance between the extractor runner and the guide is 0.15 mm. Hence, your printer needs to be properly dialed in).
4) Secure the guide with 4 M3 screws to the stepper to prevent any twisting.
5) Slowly tighten the M5 screw and watch the press-fit pulley being pulled off the stepper.

To ensure that this tool requires as little filament as possible while being fully functional, I used topology optimization in Fusion 360. This explains the slightly "weird" shape of the runner...

I hope you enjoy my design. It worked perfect for me after a ton of failed attempts to get rid of the press-fit pulleys using other designs...Check out my blog at https://allpro3d.com !

Cheers and keep making

PS:
This design prints without supports. Check the pictures for print orientation.
You may have to post-process a little bit as the tolerances are quite tight.
Especially fitting the washers and nuts into the runner can benefit from some heat to "melt" them into place.

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