Limits or homing switchs???

[tribbles]

Since I'm cutting foam, I'd be more concerned about the foam dust blocking up the optical sensors.

I'm not sure how aluminium swarf would impact magnets (sure, steel swarf would)...

I've got reed switches rather than hall effect devices (which can easily replace microswitches). However, I'm not sure about their accuracy for home switches. Since the frame of my machine is steel, I can easily move the limits since the magnets stick to it :)

(Seriously, I'd glue them down when I was satisfied they're in a good location).

[Ross77]

Cheers Guys. I started with the question of limits or homing, but the actual choice of switch seems to be the crucial factor. Theres more to this CNC malarky than meets the eye......

I've been using small microswitches because of the size constrant (and because i had them lying around) but the lever arm is really flexable and caused no end of problems as homing swithes. So Ive fitted them as negative limits (@ 0,0) but still called them homing switches and set the soft limits as -0.75 and max travel. seems to work ok.

One point that might be worth mentioning with regard to switch accuracy is the actual settings of Mach 3 (or what ever you are using). Initially I had the velocity set quite high, so it didnt take so long to setup the limits, but the acceleration was low. This meant that there was excesive over shoot when joging and the switches and soft limits didnt work resulting in lost steps. uping the acceleration improved the response and switch performance.