suggestions on post processor for home built plasma with THC?

[Tristar500]

I'm new to SheetCam but am slowly getting the hang of it.

I've built a CNC plasma cutter with a floating head. (torch is free to move up and down on a linear slide) I have a proximity switch that triggers about an inch after the torch head meets the material as it moves up the linear slide.

I want the Z to move down till it senses the material and then tell Mach to pull up (about an inch in my case) to set the torch to the proper piercing height.* I have a floating head that moves up and down and a proximity sensor that is triggered after about an inch after the torch hits the material pushing it up triggering the probe signal.*
(I hope this makes sense)
What will I need to do to instruct the machine to probe the material then pull up a certain distance (again, about an inch) so the torch is in position to fire and pierce?
I have SheetCam and am learning it. Any suggestion as to what post processor to use with Mach 3 and the CNC4PC THC-1?

[acourtjester]

Ok what you do is have the floating head as one input for the controller to use. And use the G-code with G28 for the Z axis and here is a video showing how to setup the backlash of the floating head. G-28 is for a floating head to move to a home position (down on the Z axis) of the Z until it trips the switch (torch contact).
It will zero the Z dro and retract the value you put in the post processor. Then zero the Z dro again and move to the pierce height set in the G-code (0.160"). Your example of 1" backlash is way to much, my switch backlash was about 0.028"
this video shows how it works but this is for an Ohmic sensor in place of a floating head switch, it work much faster with no offset.
I can supply you with the info on how to use this if you have a Hypertherm torch, with the circuit and module info (very cheap works great)

G-28 2.JPG (52.72 KiB) Viewed 3819 times

G-28 2.JPG (52.72 KiB) Viewed 3819 times

Here is a video showing how to find the switch offset

[Tristar500]

I was thinking that the backlash was way more than what I needed so I will make an adjustable plate for the sensor and bring it in tighter.
Thanks for the info and vids!

I'll post with an update in the next day or two.

Thank you so much!