CNC plasma | MACHINIST CORNER | Forum

I have been running an optical tracer plasma cutter since 1992 in my shop.
I love it.
Its quick and easy for me to draw a pattern, and I can cut reasonable multiple quantities with it.

I often will just trace the end of a part, or lay an assembly down on a piece of paper, draw the pattern in sharpie, and have the part cut in 15 minutes without leaving the shop.

I have some parts that are nested, 20 or 50 drawings all nested on one big piece of paper- it took a little while to draw, but then its re-usable indefinitely- I have rolled up patterns going back years and years. Drag em out every once in a while.

the computer programs are fussy- they work great for straight lines and constant radiuses, so people who do simple geometric parts like em just fine. But Autocad, which costs about as much as a new Hyundai, munches up changing radius curves for breakfast and spits out unusuable crumbs- you still have to go in and set individual points, if you are doing complicated shapes like I often do- things like human figures, or other real world drawings.

The optical trace machine is pretty bulletproof- there just isnt much to go wrong. I have auto torch height on mine, and I think that is essential. As you are cutting, the steel will warp, and move- often up and down, and if the torch cant compensate, you get ruined parts. Especially with thin stuff. I have cut a lot of 16 gage on mine, and it can move as much as an inch up in the air while you are cutting.

With big sheets, you often need to load the machine with a forklift- even a 4x8 of 1/4" weighs a bit more than a sheet of plywood- so I would guess the tables on a CNC router would get pretty beat up pretty fast, unless you were always cutting from little pieces of scrap.

Ideally, you wanna toss a 4x8 or 4x10 sheet up, and cut the whole damn thing up into little pieces, without having to do a lot of sheet handling- but inevitably, you are always sliding big pieces of scrap up and down off the table, so the table better be pretty sturdy. Mine is a water table, with slats up top, so it weighs in at a couple of tons.

Also, be aware that cnc or optical, the things put out a LOT of grime, slag, dust, smoke, and brown stuff that lands on everything. I use local point source electrostatic air cleaning, whole room fans, and the water table, and the whole room is still kinda brown...
Its a dirty process.

The Safeco field ballplayers were waterjet cut from 3/8" stainless- I didnt do those in house.
The line quality on waterjet, and lack of slag, cannot be replicated in plasma unless you step up to a HI-Def system, which is around $25,000 to $50,000 for the power supply, and generally means over $100k total system cost.
There are plasma systems out there that will cut amazingly well- but you pay for the privilege.
Typical small shop $1500 to $3000 plasma cutters just cannot give that thin of a line, or that small of a draft angle.

But I have cut some pretty complicated shapes with my machine, just not in stainless- without a non-oxygen plasma torch, (nitrogen or argon) there is much more slag/dross on SS. The HI-Def systems do NOT use shop compressed air...