Love the Smell of Burnt Aluminum in the Morning...

[BobWarfield]

;D

A nice big piece of eBay aluminum plate arrived late yesterday, so this fine Saturday morning I wanted to get started making chips out of it. Can't stand to leave a good piece of metal alone! My first task was to cut it down to size. I am building a 12" disc sander, so I wanted a piece that was about 12 1/2" square to make life easier. Several ways I could have gone about cutting out the plate. It's too big for my Multicutter, but I could have used an air cut-off tool, a sabre saw with a metal cutting blade, or the mighty Milwaukee Sawzall that lurks in one corner of the garage. Feeling a bit playful this morning, I dragged out my plasma cutter instead:

This is another of my many eBay deals. Industrial grade heavy capacity ESAB Powercut 1500 plasma purchased for an embarassingly low price. Cool looking unit isn't it? It will cut 1" aluminum and I think 1.5" steel.

It will take longer to set up a fence to guide the plasma torch than to make the cut. A big piece of stock and a couple of Kant-Twist clamps plus calibrated eyeballs will do. You'll soon see the plasma isn't all that accurate, so my eyeballs are good enough for layout!

Sorry, was by myself, so no action shots.

You can see that edge is a bit gnarly. No matter. I'm going to fit the hub I machined in the center and then spin that square plate on my rotab on the mill to make the disc round.

FWIW, that nasty slaggy cut is all me. A plasma being run at optimal feed speeds, fed smoothly and precisely, with good torch height control, and the right amperage (phew!) can make a very clean cut. Since I had no idea the right parameters and poor ability to execute them if I did, I cranked the amps and tried to keep the torch moving fairly quickly and smoothly. I think I was too slow! Miller says for 1/4" aluminum you need to be moving at 100" per minute: not quite 2" per second. I was definitely not moving that quickly.


Before this cutter I had a 110V little Hobart plasma. I sold it to an artist lady. She came over to try it and she was getting smooth flowing cuts freehand first try. It was so annoying! I'll never get that, but I do intend to build a CNC plasma table at some point.

Cheers,

BW

 

[tattoomike68]

Make a jig and burn circles. Its cheap and simple to make.

Plasma jig

Torch jig.

 

[BobWarfield]

Yep, had pondered whether to bother on this one. Decided not to.

Good to bring it up for others tho.

FWIW, I like to spin the piece being cut more than the torch. It has been easier to cobble up without getting tangled in the hose for me. Either way will work though.

Best,

BW

 

[tattoomike68]

I made a spinning table with 2" long angle iron peices for the metal to rest on.

I did alot of flame cutting for years and got to where my parts looked like a cnc cut them out. It was one of my favorite jobs to do.

 

[BobWarfield]

That spinning table is cool!

I agree, it is fun to play with welders, plasma cutters, and torches. The guys who are good are just as you say: good as CNC.

Best,

BW

 

[macona]

I see you have the current turned down. In general on plasma you run the machines full out unless you are cutting gauge thickness materials. Especially with aluminum. When plasma cutting aluminum the air does not compound with the iron like when cutting steel. Also the aluminum sops the heat away very quickly making it slower to cut.

For cutting guides I like to use epoxy fiberglass or varnished cambric materials. But that torch design on the power cuts is like cutting with a telephone pole.

No hand cut plasma looks as good as CNC.

-Macona

FWIW, I repair welding and plasma cutting equipment for a living.

 

[Don Huseman]

Reminds me when I got my plasma cutter and mounted to a track cutter my men , the forman, welder , and the patternmaker would not let me use it, it was too much fun. We bought it to cut 1/2 stainless plate. We would send it out to have it cnc plasma cut and they would charge us 1500. well it didn't take me very long that if we got our own machine for three thousand we would pay for it in about two times we had to make these parts.
Don

 

[BobWarfield]

Amazing devices, plasma cutters. Truly an evil space alien death ray, albeit of limited range, thank goodness!

At some point mine will get attached to a gantry-style CNC rig. As I mention, my hands are just not steady or coordinated enough to make the clean cuts I've seen others do. A plasma table is just about the easiest possible CNC machine to rig up, so I can't really resist!

Best,

BW

PS Macona, I cranked the knob fully clockwise and will leave it there to see how it goes! Now one question, you don't know of a good cheap supplier of consumables for my ESAB cutter, do you?

 

[macona]

There is a brand called QC Brand that is cheaper than the Esab consumables. Dont think the quality is there though.

Secret to cutting smooth cuts is templates! Make em out of plywood on a bandsaw.