PLASMA CUTTING - EXPANDED GRATING

[DRAFTZMAN]

Hello, I am trying to cut 1 1/4" expanded metal grating. There is about 1" spacing between the grating slats. The problem im having is that sometimes the torch will touch off between the slats, and it will be at the incorrect cutting height and will error out with a torch collision. The other problem is that even if the torch touches off correctly, it will cut through one bar, then shut off. Our 145 hypertherm is set to expanded metal mode. We were able to keep the torch cutting by disabling the torch height control, but our table isnt perfectly level so it still crashes.

Does anyone have experience cutting this type of grating? Our shop has installed a 12' table and a 20' table and we plan to cut grating regularly, so this is something we would like to dial in so we dont have to continue using a circular saw.

[Joey]

What are you using for a Touch off? I'm thinking you may need to make a "Foot" That attaches to the torch to give the torch a wider surface area to touch off with.

The Torch is staying ON With Expanded metal mode correct? If not I suggest hooking up the ARC OK signal from the Hypertherm so as to rule out the control relying on the THC for the Arc OK.

Can you Post a fresh report from the machine. Or at least the Plots from the CNCM folder.

[DRAFTZMAN]

Thanks for the reply, Joey. When we started we were just using the torch tip, hoping that it landed on the stock. Then we started using thin sheet metal to slide under the tip, then removing it after touch off. However that is hard to do when you have to stand at the controller and the torch is 6+ feet away. Is there any way to have the tool not touch off, and just set a height you want it to run at? We are able to keep the torch lit.

[Miengineer313]

I'm working with Draftzman on this project and thought I'd throw in my two cents regarding an explanation and cutting objective.

First, the material we're cutting is steel bar grating which comes in standard size panels, in this case it's 3Ft wide x 10Ft long and we're trying to cut rectangular shapes out of these standard panels with everything nested in Sheetcam. The steel bar grating for this job is made up of 3/16in x 1-1/4in longitudinal steel bars with welded 1/4in crossbars. All grating is A36 carbon steel. Most of the bar grating we cut is of similar size to this job for our projects and we cut a fair amount of it, so getting it to work on this CNC machine would be a huge savings.

Torch touch off on the grating itself, simply will not work, since the likelihood of getting the tip to center direclty over a bar every time is not possible, so the result is that after the first touch off, the torch head gets jammed in the grating for every touch off thereafter.

Ideally, we'd like to pursue one of two options:

Option #1 - No torch touch off at all. We simply defeat the tocuh off function, set a specifc Z height which in this case is approximately 1-1/2inches from the cutting bed (heighth of material plus a nominal running clearance), set a home position, turn the torch on and let it rip.

Option #2 - Do a torch touch off on a piece of thin sheet metal lying on the cutting bed next to the grating, go up to a specific Z height (1-12/inches), move over to the first cutting point on the grating and cut the parts with no other touch off during the program.

Looking for any feedback on how we could get either option to work in CNC12

- Brian

[Joey]

Alright to defeat the Touch off part of the Pierce macro just throw a simi colon in front of the Auto_Z_Zero part of the M61 Touch off macro.

A simi colon in from of any gcode will cause the control to skip the rest of that line.

Open the Mfunc61 from your cncm folder.
Place a semi colon in front of line 15 that says Auto_Z_zero_macro.
Save the file.

If you want to touch off again you will need to remove the semicolon from the m61.