Help choosing/modifying Post Processor for homebuilt CNC?

[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?

[Les Newell]

The 'Mach3 THC with scriber' post should do what you wnat. After selecting the post click on the 'Edit post' button. At the start of the file you should find a number of options that you need to configure to suit your machine.

[Tristar500]

Thanks Less,
I'll report back my findings.

again, many thanks!

[Tristar500]

--************************************************
--*** Set these values up to suit your machine ***
--************************************************


--Use a reference switch
--Set this to false if you do not have a reference switch
useRef = true

I set this value to true as I use my probe input and a floating head as a switch

--Use the home switch (G28.1)
--Set to false if you use the probe input (G31)
refHome=False

I set this value to False as I us my probe as a touch off switch on floating head.

--this is the distance between each torch reference in MILLIMETRES
refDistance = 250

Not sure what this means by ref distance???

--this is the reference feed rate in mm/min
refFeed = 500

I left this alone alone for now.

--Put your switch offset value here in MILLIMETRES
--Put a sheet of metal on your machine and place a sheet of paper on top.
--Slowly jog the torch down onto the paper until the touch-off switch just operates.
--Zero the Z axis then pull gently on the paper and slowly jog up until the paper slides out.
--The Z axis position is your switch offset.
switchOffset = 5

I set the offset and entered in mm.

[Tristar500]

When trying to cur a simple 6 inch line on a very slight incline I get no motion from the z and the tip crashes into the material.

Again, NO z movement. Have THC enabled in Mach screen.

I'm attaching the G cod

6inchline..txt

(591 Bytes) Downloaded 142 times

e in case that may be helpful.

Thanks all!

[Les Newell]

Your settings look reasonable apart from refHome. It should be:

Code: Select all

refHome=false

Note that false is all lower case.

Not sure what this means by ref distance???

If you have multiple pierces close together the post won't bother to re-reference on each pierce. refDistance controls how far the torch has to move beforfe it references again. Lasve this as is for now.

At what coordinates does the torch crash into the work? If it is at X0 Y0 I'd say your touch-off may not be working correctly.

I'm seeing an M62P4 in your code. That looks like the result of a cutting rule. Is Mach3 configured to understand M62?

[Tristar500]

Hi,
touch off and arc start seems ok.
the machine will cut the entire 6 inch line put with no Z movement and simply pushes the floating head upward as the torch travels up the incline.

"I'm seeing an M62P4 in your code. That looks like the result of a cutting rule. Is Mach3 configured to understand M62?"
I don't know. Is this a macro thing? How would I check to see if Mach 3 is configured to understand M62?

Thanks for your help here!

[Tristar500]

I just got word back from the guy at CNC4PC and he says that Mach3 does not support M26/M63.

He suggested using post Mach3 plasma no Z.scpost while he's working on a better version for the THC.