Homing/Limits

I am not planning on using a positive Z limit switch since I don't see much benefit from this since it all depends on the length of the workpiece. The negative Z axis limit will be installed near the fixed end of the ballscrew. A plastic cover screws over this.

There are heaps of micro switches available from Ebay. I used the smallest ones I could find, but of course they are not waterproof. But they are placed under the slides and I am pretty confident that I can keep them dry. Roller type would probably be better. I bought a set of these, but they are a little too large for my application. In the end, I went with cheap micro switches.

For X axis I placed the negative limit switch under the slide away from swarf and coolant. This will also be configured as a home switch as well. It is wired as normally closed.

Video1 shows the switch acting as a limit, fast jogging until the switch triggers an e-stop.

Video 2 shows the same switch acting as a home switch, moving onto the switch until it triggers, then moving off until the switch resets.

I placed the Z limit near the Z axis fixed bearing block behind an aluminium plate. One wire runs under the ballscrew cover. The other wire which runs to the X limit is only wired temporarily for testing. I need to find a way to run this neatly. I could run it on top of the X slide, but I don't want to run it in parallel with the stepper cable as I have read interference can be a problem as the wires are not shielded. Maybe I will replace with shielded. The picture shows how it fits.

Video 3 shows both axes homing. Notice how it triggers the stop then they back off a small amount to release trigger. This is very repeatable.

I setup soft limits on the positive limit for both axes. Video 4 shows the soft limit triggering the Z axis.

Videos