End stop suggestions for Duet controlled CNC Mill

  • Waterproof is a must and needs to repeat within .025 mm. I can get a bulky mechanical switch but this is for a tiny mill so i'm trying to avoid "bulky". I guess that leaves an optical or proximity type switch or?? Some guidance would be greatly appreciated.

  • Have you considered motor stall detection?

  • @zapta I would not recommend stall detection for CNC mills/routers. The steppers usually have a lot more torque than in 3D printers because of the force needed to push the cutter through the material. So after a few stall detection cycles something might break.

    @3DPMicro An inductive switch might do the trick. They are waterproof by design. Alternatively, I recall I have seen some switches with a thin rubber cap over the button. Misumi has quite a few options, but they are on the expensive side, with all of them more than 40EUR.

  • I use inductive switches, looks like the PINDA probe but 12mm diameter. They are more repeatable than I can measure. Also used some smaller rectangular sensors before, found the threaded body easier to adjust though.

    Only challenge with the Duet is most of the industrial ones need 12-24v, refer to the wiki for how to connect these to Duet. https://duet3d.dozuki.com/Wiki/Connecting_a_Z_probe#Section_NPN_output_normally_open_inductive_or_capacitive_sensor

  • Thanks for the suggestions gents. I didn't think about using stall detection and although I would agree it may not seem well suited for a high power milling application this isn't really a high power application. 12.5 N/cm nema 14's with 1 mm lead ball screws do generate over 50 kilos of force though. Reading up on it I do think repeatability would be an issue (+-2 full steps) which may be worse with the high reduction from the 1 mm lead.
    I'll try some cheap inductive switches from eBay and go up for on there if needed.

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