First Test Cuts to define cutting parameters


I ran a few test cuts on my machine for the first time to define the best cutting parameters to use going forward. I uploaded some pictures for review and input on my results. Since this is my first time using a plasma table I’m not sure if my results are normal or if I can tweak my settings for better results.

I’m using a Thermal Dynamics Cutmaster 40 with a 30 amp tip. Inlet air pressure for the machine is rated at 90 - 125 psi. I have it set at 100 psi. Cutting standoff range is 1/8" - 3/8". Output current is set at 30 amps.
Material thickness is 16 gauge. Pierce height = .5", Plunge rate = 100 ipm, Cut height = .25", Pause at end of cut = .3 s.
I have the powered Z - Axis installed on the machine with THC working properly.

This is a two inch square with different size circles from 1/8" to 1/2". I performed three tests with feed rates of 100 ipm, 125 ipm, & 150 ipm respectively with reference from left to right on the pictures. All of the cuts regardless of feed rate produced bevels where the bottom of the cuts were slightly smaller in diameter than the top. Dross formation on the bottom of the plates seems to be about the same regardless of feed rate although from my perspective it looks like maybe there was less of it at 100 ipm. NOTE: I did run one test at 150 ipm @ 35 amps for comparison but the results were about the same with the exception of cutting down deeper onto the slats.

Suggestions on tweaking my parameters for better results would be appreciated!

Hey congrats on your first cuts even though they may not be perfect! You’re on your way!!

I’m thinking your pierce height and cut height are too high. I set my pierce height at .15" and my cut height at .06 for 16 gauge. Because your torch flame is well… flame shaped it does have a natural taper to it so if the torch is too high you’ll see more bevel on cuts.

I don’t have a thermal dynamics so others may be able to chime in with plasma particulars but that’s what I see at a first glance.

Improve Plasma Cuts.pdf (759.7 KB)
this can help a bit…

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Thank you. I’ll make note of that and adjust those parameters.

I just read the pdf you provided and it confirms what @bobdobqb suggested. Thank you both!

no problem…do some searches using the little magifying glass on the top right of the screen…use key words like Taper cut…torch height…it might help you with some of your problems…then again you might get confused…but that is why we are here…to help

Hey thanks @toolboy. I’ve been meaning to download that PDF because it’s a good reference. Thanks for making it easy for me :laughing:

Takes a while to get it all dialled in and there’s a lot of of stuff to wrap your head around. I’m definitely a fan of using simple geometric shapes for any testing. :+1:

One more thing that just popped into my head is that I also slow the cut speed down when I’m cutting smaller circles.

Copy that!

Here is an update on my results after modifying my settings per your suggestions @toolboy and @bobdobqb. I ran the same test cuts with the “Circles” file that I posted pictures of previously. The problem I was having with the beveled cuts is now corrected! The dross is now reduced and most breaks off with a flick of a flat head screwdriver. Here is a picture of my first official cut. The top came out clean and the bottom doesn’t look bad. Again, most of the dross flicked off. The rest I’ll have to put a little work into it. I’m very happy with the results. Thanks again to both of you!


great to hear and thanks.
just keep notes on how things cut…make a small test pattern to try different settings on…
I am still doing that after a year…

Good to see!. Glad we could help you out. :+1:

Like @toolboy says, keep notes.

Oh this is good, thank you. This echoes and expands on some of the stuff in the welding textbook I bought so I could figure out if I even know the fundamentals of anything yet, of course I don’t. For some reason jumping into the deep end is usually my first step then I have to go back and learn the details of the basics. Anyway here’s some stuff from bowditch textbook that might just be useful for saying the same things a slightly different way: