Changing the amperage on machine

Probably not the brightest question but do I need to change/when do I change the amperage on my plasma cutter? Do I set that based on the material thickness etc. or just leave it on one setting no matter what thickness I am cutting?

There are a few schools of thought here. Some of the decision is based on what plasma cutter you have. If you have just one choice of nozzle then you can use a set amperage like 40 amps and then vary your cut speed based on the material thickness you are dealing with. Another approach is to vary the amperage based on the speed that you want to cut or that is appropriate for your design. The third method is if you have the ability to use different amperage capacity tips then you have different amperage’s and speeds you use again based on the material your cutting and the amperage capacity and design your dealing with. There are a lot of variables. Hopefully this didn’t muddy the waters too much. Share with us your cutter information and what you’re working non and it might we can share more help on this topic with you. Welcome to the forum


Thanks! Made complete sense. I have this is a sculpture studio at a university so probably will not be able to change capacity tips for every student and every cut. I like the fact that I might be able to just adjust the amperage and speed for every project and leave the tips alone (hopefully). I have a Razorweld 45 and cutting 12-18 gauge steel.

I believe that machine has one standard sized tip. In that situation and based on the material you anticipate cutting I would ask the following question is speed or fine detail cutting most important? If fine detail is the most important I would suggest using a little lower amperage setting so that you can utilize speeds in the lower ranges. It might all be in my head but in the sub 140ipm range everything seems less jerky and less vibration. If speed is more important then I would crank the amperage up and uses as fast of speed as possible to achieve best cuts.

HUGE help, thank you!!!

You’re very welcome.

If you have A razor weld torch there is only one size tip/nozzle rated at 40-45 amps.
So adjusting the amperage does not make much difference. I think you can get aftermarket torch for the R/W that has different size tips available.
Sounds like for you, just setting it to 40-45 amps for most your cutting.


Ok, sounds good. Two followup questions on that. Since I will need to leave the amperage that high, would I still be able to get some detail cuts with 22 gauge steel? Also, does this mean my kerf widths, etc will not change?

I really cant tell you as I have never cut anything under 14ga. I think 22 ga might be tough at 45 amps unless your doing very simple geometry you can very fast. Some people will get good cuts with settings that other people wont. Does not hurt to try different settings.

If I was going to cut 22ga I would do a Search (top right hand side) and see what you can find there for 22ga.

Your kerf will not change. When I ran a rw45 I did turn down the amps to cut thinner stuff. The thinner stuff definitely needs faster speeds.

I don’t have a lot of experience cutting thinner material than 14 ga . There is a rw45 cut chart floating around. The best advise I can give would be make a few small designs. Jump in do some test cuts. Each machine you see will cut a little different considering how it is setup.


What many recommend is to use a test cutting sample and vary the things that you have control of.

There are two great examples of this in FireShare:
They use minimal material and help you see many things of you setup: small holes, inside curves, outside curves. If you have lots of dross on the top you are moving too fast. If there is lots of dross on the bottom you are moving too slow. Also, if you are moving too slow you will also burn away more material so you will see that the holes are larger than you intended.

If you find that your lead ins are burning some of your intended project then you might speed up the lead in.

Of course, the above suggestions assume you are keeping the amperage the same. To grossly generalize: High amperage and slow speed have similar results. Low amperage and fast speeds have similar results. You will find other issues with thicker material such a sloped kerf if the cutter is moving too fast on curves. You are unlikely to see that slope with thin material but a one inch hole should be a one inch hole when you are done cutting if your settings are on target.