Tapered cut due to THC?

Hello to all,

So i noticed my cuts have a taper on all sides of the part which would indicate my torch is to far away and I am cutting with the lower portion of my plasma arc. Can someone point me in the right direction for proper setup or manual adjustment of parameters? Being new to cnc plasma, I was thinking my torch height control would be compensating or correcting while cutting once initial voltage test was completed when I built the table. Below are some specifics, please advise if you need addituonal info to diagnose!

The taper of cut is narrows at top edges of the part and widens at the bottom if anyone is curious.

I have ran 3/16 down to 16ga and notice it on all sizes with thicker material being more obvious.

I am using fusion 360 for CAM

Yeah we need to know what cutter you’re using. Are you cutting the correct direction, with enough power at the right speed?

Some taper will occur with plasma. It can be mitigated, but there is still a chance to get some.

99 percent chance this is a result of settings, not THC.

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Plasma cutting always leaves a taper, especially on tight features like holes. 3 to 5 degrees is considered normal. Have you measured your taper? How much is ?

I have not measured the deviation from 90 degrees yet. I agree that smaller hole taper is a thing, BUT my straight cuts are just as bad, is 3 to 5 degrees typical on straight cuts as well…assuming consumables, speeds etc are all proper?

Taper growth, from what I have read, occurs as the consumables wear. So this might be a contributing factor.
FYI, punched holes measure differently on the punch and break-out sides, aka the burr side.

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Cutting with hypertherm 65
Material 14 ga mild steel
45 amp fine cut consumables
45 amps at 185 ipm
Cutting clockwise direction

What’s your live voltage reading during the cut and what’s your cut height set to?

Cut height is at .06" , but my live voltage i am not sure of and i am away from the machine until this evening…but I did not think to look at that voltagr readout when cutting so I will double check that and get gack to you.

If you see the live voltage really low, then you have some interference. Usually from the computer being plugged into a grounded outlet while cutting. This will cause the torch to raise to try and up the voltage into normal range.

But, some taper is normal. I will say that I cut some 1/2 inch recently and there was hardly any taper on the outside contours.

Post some pics of what you’re concerned about and we may be able to reassure you it’s normal.


I measured my last cut project as I was leaving for the campgrounds and the taper does appear to fall in the 2 to 3 degree category, but I have yet to review the live voltage due to being away from the shop…more to come, here is a photo as well.