Me and a buddy are making a 5 axis desktop cnc and we have the rotational axis complete. The problem lies in the homing. What is the best way/type of limit switch we could use and how to use it in the best way? We would like to be able to keep an accurate home and still allow the rotation to exceed a complete 360 so mechanical is out of the question. Thank you!
hall switch, induction switch, or absolute encoder?
We are asking your guys help on your opinion on whats best. With our current optical switches we cant get it to home the way we hoped. We are asking what everyone else is doing and how they did it.
This group uses a 2 motor 2.5d mill setup with a router, so a 4 axis setup is way out of scope here. I have an induction sensor on a 3D printer. Hall sensors are used on cars for crank and cam position sensors, so if optical doesn’t work, you can use electric or magnetic field effects to get you there… best of luck!
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Although it would be cool if someone invented a embedded rotational axis…
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I would use an absolute rotary encoder, or if all you care about is home then an optical encoder that detected home only. It could be as simple as a disk with a hole, led, and photodetector. The detector will have a range, an example would be 0 to 2 degrees (I made that up, reality will be different) so you’ll need to always home in the same direction.
It is very much off topic for a Maslow, a 3 axis router with chain driven X and Y, but we enjoy non-Maslow discussions only. Just don’t expect us to be experts on other devices. I have a rotary axis BobsCNC Revolution, and plan to add a home position sensor to the rotary axis, but it hasn’t worked up to the top of the to-do list. The grbl controller has been replaced with one running FluidNC on an ESP32, which provides 6 axis (x,y,z,a,b,c) support along with a web interface, plus bluetooth and USB for data transfer. The firmware supports uploading to, and running from, an SD card, although my minimal price implementation ($10 wemos ESPDuino board, CNC shield V3 with the onboard pullup resistor removed, and DRV8832 pololu boards) lacks an sd card socket. It’s using X, Z, and A, there’s one more driver socket available for another axis. The board can provide step/dir to external drivers, and for the minimal cost is still worth it for convenience.
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The AMS family of magnetic encoders are excellent if you are looking for one to use
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