CNC machines normally need limit and home switches to tell the computer where the various moving bits are. Limit switches stop the computer from trying to run the machine off the end of any of the runners, and home switches give the computer a datum point — a way to say “OK, we’ll call this place 0 on all the axes, so do all your measurements from here from now on”.

I’m only putting home switches on my machine because it’s always going to be run attended, and even if noone’s there to stop it, it’s not capable of doing itself too much damage as the motors are pretty weak.

Here’s the switch on the X-axis – you can just see the carriage on the upper right of the picture, and as it moves left, it hits the switch and the computer knows it’s home.

Harder to see but the Y-axis home switch is similar:

The Z-axis is trickier, as there’s not a lot of travel up and down so the switch probably needs to be adjustable, plus it’s in a pretty confined location. Could do with a little bracket:

The machine took about 10 minutes to mill it out:

… and me about 2 minutes to sand the edges:

Little switch attached:

And finally, mounted in position:

Yay – you can now tell the computer to “Home all axes” and it moves each axis of the machine back until it hits its switch.

To make things a little more stable I added an extra bearing to the bottom of each side of the platform to stop it twisting up and off the rails:

I added a little light behind the Dremel spindle cos everything looks better with lights on:

That’s it for now. Next job is to sort out the work platform – make sure it’s level, and create some little clamps to hold the work down as the mill is working on it.