No CAM option for Rotary QtPlasmac?!

27 May 2023 09:19 #272253 by santy
Hey guys!

I have built a fully functional pipe cutting machine, with double A axis.
I'm using a motorized lathe 125mm chuck in the back with 4 jaws, and another motorized self-machined chuck in the front with one of those big hollow bearings with outside mod2 teeth, and a self-centering clamping mechanism.

I've made custom hal changes to make these axis tandem of each other, even though they have a different stepper scale. I've used mult2 in hal file to multiply the steps and velocity outputs from original A axis to a and send them to another stepgen.

The problem is SheetCAM.

I'm using A as Rotary, and XYZ as normal axes. the problem is that sheetcam (paid version) allows me to generate the toolpath i want for the pipe that i want, but when i run the post processor, it is not compatible with QtPlasmaC.

I'm testing the machine with conversational built codes, like making a circle in conversational, then saving the program and manually adding "G0 A90" before the end, then another circle, then "G0 A180" or something like that, because Sheetcam generates gcode with a different format:

For example, it gives me an error for touchoff as it sends a different code to touchoff than what conversational generates: N0110 o<touchoff> call [34.000] [1] [2] (Touchoff and start cutting) 
Or it gives me an error as 'arc end differs from arc start". as i tried to change the "OnPenDown" function.
I want to run a full "cut around" of a pipe which requires me to simultaneously control all 4 Axis, and i can't program it manually of course, and sheetcam isn't helping.
I tried with a post processor which is in this forum, "Grotius" made it, and i've also tried with "linuxcnc plasma rotatif".
Any ideas as what i could do to achieve this? I send some samples of generated code with sheetcam.

Thank you!

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27 May 2023 09:49 #272255 by tommylight

Probably could have done it without mult2 in hal as i am pretty sure LinuxCNC can cope with tandem axis using different scales/step rates but i have never tried it.

For round tube, i use 3 axis only, works perfectly well, just needs a config for each diameter of material. Also makes it easier for people using it, once they figure out a tube is just a bent sheet.

As for SheetCAM, disable probing, QtPlasmaC does that automaticaly, no need for Z thouchoff, ever.
Did you try using the edited post processor from this forum? Although it should be included it SheetCAM, i think.
I did start a while back editing the wizards in QtPlasmaC, but did not get far due to lack if time, but should be easy enough for simple 4 axis stuff as the material dimensions are standard and have 4 faces so the A (B or C) axis have to move in steps of 90 degrees.
Does require some math though for the radii and motion when cutting those while A and Z are moving, and ...

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27 May 2023 09:57 #272256 by santy
My A axis is rotary, in angles, should i have done it some other way? I have no idea in this part.

Yes exactly, for a round pipe i would be comfortable using the 3 axis setup, but thats whats most complicated for me, as i need the X and A axis in my setup, for example to cut letters above a rectangular tube.

i changed the sheetcam "linuxcnc plasma rotatif" pendown function from:

function OnPenDown()
local matZ = sc.QueryDll(qryCHKEND, endY, dllId)
post.NonModalNumber(" o<touchoff> call [" ,(pierceHeight + matZ) * scale ,"0.000" )
post.Text ("] ")
post.NonModalNumber("[", pierceDelay * scale, "0.##")
post.Text ("] ")
post.NonModalNumber("[", cutHeight * scale, "0.##")
post.Text ("] (Touchoff and start cutting)\n")
post.NonModalNumber (" F", feedRate * scale, "0.###")


function OnPenDown()
post.Text (' M3 $0 S1 (plasma start)\n')

i still get errors "arc start radius differs from arc end" something like this and can't play the code.
also, what could i do to choose what program (sheetcam or qtplasmac) is managing the material properties and parameters within this gcode?

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27 May 2023 10:11 #272257 by tommylight
"arc start radius differs from arc end"
Check the tool table, usually that error is due to tool being to large to cut the radius's or when starting a cut on a radius.

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27 May 2023 11:17 #272259 by santy
im not with the machine now but i think i managed it. i was also using Y for the tube feed and X for horizontal movement of the torch, but its supposed to be the opposite for the post processor that doesn't require probe made by grotius.

not requiring a probe is great because i was not yet testing this with the plasma cutter and i was using current passthrough to use it as probe, as i didn't want to implement a floating head... ohmic probe was not very good... so this is great.

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27 May 2023 14:24 #272267 by tommylight
QtPlasmaC, PlasmaC, Toma_THC, all require floating head, but the first two also work with ohmic probing.
If you have none of those, none of the configs will work for you. so you are better off using a normal plain config without automated Z stuff.

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28 May 2023 13:20 #272338 by santy
this way is a lot more efficient. have been playing around and finally got it to work in gmocappy/axis .. but will try to find something more plasma-related to use it on.

is there a way to disable automated probing in qtplasmac or plasmac? this would be useful for me for another project as well.

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