STV, Myplasm and Sheetcam oh my!

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broken
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STV, Myplasm and Sheetcam oh my!

Post by broken » Wed Jul 21, 2021 12:12 am

Hi Guys, been using forums since the very beginning of the interwebs, it's where the real knowledge and information is.

We recently got an STV 5 x 5 table running the MyPlasm controller/software with a Hypertherm 45 torch.
While we've been able to get some usable stuff out of it there are some issues that no amount of turning the torch in the holder, speed, height, thc voltage, etc, will get rid of. Namely some of the holes are just trash both top and bottom, all we've been able to do is make them less bad so a bolt will drop through.

MyPlasm won't let you change the direction of the cut so it was suggested we try Sheetcam to reverse the cut direction and use it to generate the G-code.
After saving it as a .TAP file, which produces no errors, trying to load into MyPlasm (says it can do TAP files) results in 'file load error'.
I've tried TAP files from both the free and paid versions of Sheetcam with the same result.

Do I need a different post processor that is compatible with this controller/software? Is that a thing?
Do any of you agree/disagree that changing the cut direction can improve hole shape?

I'm not asking for perfect, just seems like my results are outside of what most of you would consider 'good'.
Thanks guys.

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djreiswig
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Re: STV, Myplasm and Sheetcam oh my!

Post by djreiswig » Wed Jul 21, 2021 10:05 am

You need a post processor that formats the gcode correctly. There are a ton of them for SheetCam. I would guess there is one for myplasm, but I'm not sure.
If you're cutting the wrong direction that could definitely affect your quality.
2014 Bulltear (StarLab) 4x8
C&CNC EtherCut
Mach3, SheetCam, Draftsight
Hypertherm PM65
Oxy/Acetylene Flame Torch
Pneumatic Plate Marker, Ohmic, 10 inch Rotary Chuck (in progress)

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acourtjester
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Re: STV, Myplasm and Sheetcam oh my!

Post by acourtjester » Wed Jul 21, 2021 11:17 am

Have you contacted Les with SheetCam about a custom post processor, he has done this in the past and with more people using Myplasm units.
I know there are members here that use that unit. Reversing the direction has its purpose and is used for different direction for inside and outside cuts, due to the plasma swirl pattern. Another thing does the Myplasm import .NC files these are another form of CNC files similar to .tap
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: STV, Myplasm and Sheetcam oh my!

Post by weldguy » Wed Jul 21, 2021 1:41 pm

What direction are your interior circles being cut in? CW or CCW?

Can you post pics of your cut so we can see what your interior or small holes look like?

broken
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Re: STV, Myplasm and Sheetcam oh my!

Post by broken » Wed Jul 21, 2021 9:52 pm

Thanks for taking an interest fellas.
I have not contacted Les since I was using the trail version to test the direction theory, If it looks like it would help my problem I will certainly buy the license and ask for his help with the post processor.

The outside cut goes clockwise, the internal cut and holes go counter clockwise.
The one on the left is where we started, and the right is as clean as we can get with just speed, height etc. the metal is .120
and I've oriented them the same direction they were cut, the top is better than the bottom. Holes are .390 for .375 bolt

The next part I start to turn out will need to be tighter tolerance than these holes will seem to allow.
Am I asking too much or do you feel the direction will help here?
20210721_190827_resized.jpg
Thank you!

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acourtjester
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Re: STV, Myplasm and Sheetcam oh my!

Post by acourtjester » Thu Jul 22, 2021 9:06 am

Ok you realize you can also plan how you cut a object, meaning you can cut on the line, inside the line and outside the line. This is controlled by the kerf diameter, inside the line for a circle shoud give you the correct inside diameter. And outside for the outer cut for parts. The one on the line can be used for metal scribing, drag knife, and some routing to exactly follow the line. Here is what a drag knife project look like.
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

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