What Señor Vega said. Aluminum takes more juice to plasma cut than steel does, due in part, I think, to its tendency to immediately form aluminum oxides, which melt at a waaaay higher temp than aluminum. Also, the aluminum has a much higher rate of thermal conductivity than steel, so it dissipates the cutting heat quicker.

For cutting aluminum, you want to have the stuff as clean as possible. De-grease with TSP or solvent, then rinse and dry. Scuff lightly with a Scotchbriteâ„¢ pad to remove oxides, then cut promptly. It will still take about 50% more juice than a comparable thickness of mild steel. So, if your plasma rig can conveniently and cleanly cut 3/8" steel, you can get the same results with aluminum up to about 1/4", possibly 5/16" on some alloys.

For stuff where you need a pretty precise cut, and can afford the time, you can cut 3/16" 6061-T6 reasonable well with a jig saw or a router. For straight cuts, I usually just use a Skilsaw or a table saw and high tooth-count carbide tipped blade, one with a triple-chip tooth grind.

When cutting sheet metal or plastic with a jig saw, I do it on top of a sheet of 3" thick hard styrofoam insulating board. The blue stuff, not the wimpy white beadboard crap. That way, the stock doesn't flop around and invite blade breakage and nasty language. The same sheet of styrofoam can be used hundreds of times; as long as it is thicker than the maximum penetration of your blade, it stays together.

Kimberli,

Bill's points are very much on target. If your plasma unit isn't big enough, you just can't hope to make it work. Even if it is, you'll have to either want rough edges or work like a dog to finish them. The placer cutting or CNC router would be much faster and easier, and leave very little cleanup.

If you check with an outfit that can do the cutting, find out what format CAD file they need to run the cutter. Then supply your drawings in that format and you'll get better results and a lower price.

Using either placer or CNC won't eliminate all the cleanup, though. You'll still have to do some hand work to get the fine detais you want like sharp inside corners, etc. Even so, it will be about one tenth of one percent of the cleanup from hand-held cutting. And, of course, the surface finish will still be up to you.

The other pooint Bill made that is very cogent is that of material thickness vis-a-vis your design. If you are going to have long, narrow elements, you will want to cut a few practice pieces to see if the thickness you're thinking of will have the required rigidity in narrow sections.