Getting back to LinuxCNC plasma table

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acourtjester
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Re: Getting back to LinuxCNC plasma table

Post by acourtjester »

Yes I received a reply from Les with that info and created code snippets with those M codes and save a G-code using the LinuxCNC PlasmaC post processor. I have not tried it yet but since it is from the QTPlasmaC manual it should not have a problem. There is another path concerning the problem from the Linux Blog concerning the Latency error I randomly get which my be the real problem. I will report back after I do some test cutting.
Test cut rules.JPG
test cut rules list.JPG
test cut rules list.JPG (24.55 KiB) Viewed 318 times
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tcaudle
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Re: Getting back to LinuxCNC plasma table

Post by tcaudle »

not sure how the ON works but usually commands are modal meaning they last until they are changed .
That Pos t has a bunch of legacy MACH stuff commented out (wrapped in quotes so engine ignores it as a comment.

the Commandcnc version of Linuxcnc uses another M code sequence to enable and disable the THC and code handles both actions. So when the torch fires at the pierce height the THC is turned off by code (actuall when it initializes) then when the Z moves from pierce height to cut heaight (plunge) it triggers the DTHC to turn on . Its done that way because it factors out any pierce delay or plunge time. THEN if the cut is greater tahn the "min cut length of DTHC " in SheetCAM it starts the DTHC delay timer. That is another value in the g-code from the tool table.

The DTHC is turned off at the end of each cut if its on. So each cut is done as a separate process.

For a code snip like EOC the distance is in the value of the snip and then the correct Macro is called to turn off the DTHC . In CommandCNC it an M68 and M57 type call.
We also can embed power settings (amps) into he codes to use the RS485 on properly equipped Hyperthem units.

You need to make the distance long enough to turn off BEFORE you get tot he lead out . Turning the THC off after its passed the actual end and into the lead out does you no good. A 1/4" moving at over 200 IPM happens really fast .

So edit your Cut Rule to include the M62 P2 call and see if you need to turn the THC logic back on before the next cut

You might want to have a look at the CommandCNC Post processor for SheetCAM to see how it done there. SheetCAM has a powerful ability to put in variables that show up as values in the Operations window and in the tool table . You can download the Posts off our SUPPORT/DOWNLOADS page of the website.

I don't know how much you can control or override the QTPlasmaC multitude of settings

We do not advocate for using Cut Rules excpt for the End of Cut (EOC) . Other settings in the tools and operations take care of setting automatic rules
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acourtjester
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Re: Getting back to LinuxCNC plasma table

Post by acourtjester »

I just finished cutting 2 G-codes after a computer BIOS (turn off Hyperthreading) and changes to software in LinuxCNC. Both cuts were successfully cutting with out errors, I did notice a slight dive at the end with the first G-code so I increased the THC turn off before end to 0.500" and don't think it happened on the last cuts. the G-code parts had some sharp turns without a problem. The members over at LinuxCNC forum have been great help.
first cut
6 parts.JPG
second cut
2 parts.JPG
DIY 4X4 Plasma/Router Table
Hypertherm PM65 Machine Torch
Drag Knife and Scribe
Miller Mig welder
13" metal lathe
Small Mill
Everlast PowerTig 255 EXT
weldguy
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Re: Getting back to LinuxCNC plasma table

Post by weldguy »

Very cool Tom. I would love to take some time to look into the Linux plasma world. Hopefully some day!
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