limit switches on cnc

[dfox1787]

Hi Guys

Im looking at installing limit switches on my cnc.

Will 3 switches be enough on a 3 axis cnc? I know ideally i could do with 6 but there is no way for me to install a limit switch on the z- without loosing a small amount of work area on the x axis.

[Neale]

Limit switches at one end of X and Y to act, mainly, as home switches, plus one at the top of Z travel, is a reasonable minimum. If you set up your soft limits properly, that's probably OK for a machine that also has physical limits to movement. Soft limits will stop the machine running into the physical stops except in cases of major failure, but home switches are pretty much essential for ease of use. It's really valuable to be able to hit a button, home all axes, and work from a known machine position. Doesn't really matter if the home switches are at min or max travel, or a mix of both. Can configure Mach3/LinuxCNC to suit. However, limit switch at bottom of Z travel isn't of much use as there isn't really a definite "bottom Z travel" position. That's why you normally home Z to the top of travel.

[cropwell]

A limit switch on Z-- is not usual. So I presume you could install the other 5. If you are using Mach3 you have the facility of soft limits, I.E. once you have homed your machine mach 3 knows where it is and the dimensions of your work area are configured - but don't ask me how I have 5 limit switches so have never been there.

Neale stepped in while I was checking something before posting - so overlap 80% on replies

[EddyCurrent]

You can mount a limit switch in the centre of travel then use an adjustable striker at each end.

Picture shows central limit switch and adjustable striker at each end.

[dfox1787]

Thank you for all your responses.


Ill use three limti switches for homing and maybe a the extra 2 if i need them but ill try using soft limits and see how it goes.