Z axis question.

Creative25 wrote:

Do you need two endstops and homing for the Z axis? Or is the floating switch also acting as the lower limit?

You technically don't need any. You could elect to home the axis in place. But this requires parking it near the top each time and is generally a PITA. Most of us run one switch for homing at the top of Z+. The lower limit is controlled by setting Z axis minimum limit. This is referred to as a "soft limit". Once you home using the limit switch, the software will only let the axis travel as far as you set the minimum limit.

This is of course a generalization, you can set linuxcnc up to do a whole bunch of different things. Sky's the limit.

Does the floating switch act as the homing switch as well?

I suppose you could do that, but I don't think you would want to. If the material were lower than the point you probed to get your home position, you wouldn't be able to reach it.

Max limit and float switch are required for comfortable use of Z axis.
Float switch needs to be on a separate rail on Z axis.

Creative25 wrote:

Du you suggest have min and Max limit for z axis so as to make sure you want reach the lower hard stop.

I just wonder how big is the chances of overrunning a softstop, I guess that will happen mostly during setup?

I've never ran past the lower soft stop. Supposing your steppers don't lose steps, you shouldn't either once you get everything setup right.

Creative25 wrote:

Ok so before I install plasma c

My machine Schuld have the following.

Limits for all axis including XYYZ

Stepper Motors tuned plus soft limits

Estop

Is it useful to have jogging buttons hardwired to the Mesa 7i76e board wat is the most common setup in this regard? Of do people use Usb keypads?


So basically floating switch ohmic sensing arc ok torch on relay all get connected after plasma c installation?

Correct. Have a working, home-able machine. Most of us use USB keyboards to jog around, or jog pendants.

You can connect those things, just note what inputs/outputs you use. They will get entered into the configurator later. There is no place to input them in PNCCONF.

Consider installing QtPlasmaC. Development for the PlasmaC GUI has stopped.

linuxcnc.org/docs/devel/html/plasma/qtplasmac.html

Creative25 wrote:

Great I’m getting more understanding. So now my last question do you recommend using the same pin for upper and lower limits + homing Are there any disadvantages to this setup?

I'd have to look at my setup, but I'm pretty sure I have my sensor set up as a home + limit switch. First it's a home switch, and after it's homed it becomes a limit switch in LinuxCNC.

As I mentioned, I have no sensor on the lower limit. I rely on LinuxCNC's Soft Limits to take care of that for me. Works great.