Rule of thumb for plasma cutting?

[Gadget]

Hi Guys:
During my time in the shipyard (40+ years) about 10 years were running a 300 amp CNC plasma cutter on a 10’ X 40’ water table, I have cut thousands of tons of steel, stainless and aluminum from 1/8” to 3/4" thick, I don’t think there is much need for setting the amps on these small torches, just turrn them on full and go, and changes the speed of your cut to accommodate different thicknesses, if you have different consumables you might test the differences between the large and the small tips… While I was running the 300 amp machine (other than making sure your tip is clean and not burnt out), the tip size, gas (air) pressure (we used nitrogen), speed of travel, and the height of the torch were the only things that were considered.
I hope this clears up some of the controversy covering machine settings.
Bob

Woofer,
On my CNC table (home built) I cannot always get the speed I would like. In that case wouldn't it be better to dial down the amperage to compensate for the slower speed?

Dan

[woofer456]

Traveling too fast will cause the plasma to drag back and you will get a poor cut if the tip is bad or the speed is too slow you will have a lot of slag and have a hard time keeping the torch going, as the metal will blow out and you lose your connection. As far as turning the amps down, I don’t think that will have an affect other than maybe not having enough power to go carry the cut
Bob

[HerbD]

Thanks Woofer,

My informal testing last weekend, varying amps, speed, air pressure, etc. seemed to run along the lines of what you describe in your last post. I was going to re-run the tests, keeping better records of what was happening this next weekend. I'll still do the tests and share what I find along with pictures.

Thanks for sharing your wealth of experience since a few of the previous outcomes seemed counter intuitive.

HerbD