The shaft on my coffee grinder started to wear of due to the flat crank handle with small surface area; therefore I was looking for a crank handle replacement. I remixed an existing design of the rotary crank handle to improve upon its several shortcomings.

Improvements

• Metal screw is added to the knob to improve robustness
• teflon tube is mounted on the screw to minimize friction
• contact surface area at the pentagonal shaft is maximized

List of materials

1. truss head M4x30mm screw
2. M4 washer
3. M4 nut
4. teflon tube OD 4mm, ID 3mm, cut to 9mm length
5. 3d printed knob
6. 3d printed crank

Notes

A smaller teflon tube is used used intentionally to get a tight fit on the M4 screw. First, I screwed a teflon tube on the screw gently using pliers and then cut it down to required length.

Geeetech Prusa i3

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No

0.2

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