[TheForge] Re:3 axis plasma cutting

[Ries Niemi]

Shannell-
My optical trace plasma cutter is made by C&G Systems, which is a 
subsidiary of Thermadyne, which makes thermal dynamics plasma cutters.
It is a manual machine- no computer whatsoever.
It does have a small amount of electronic circuitry- It uses an HL-8 
electric eye that has its own built in light, which illuminates the 
line on the drawing. I make a drawing on 4 foot wide butcher paper, 
using a sharpie felt pen. If I make a mistake, I use white-out, and 
redraw.
Then you put the drawing on the 4x8 steel table, and the eye will read 
the drawing.
You manually start and stop the machine- one button turns on the plasma 
power supply and begins the motion of the electric eye, and 
simultaneously the torch. You can control the speed from the main 
control panel in Inches per minute. you can remotely adjust the torch 
height before you begin the cut- after that the auto sensing circuit 
moves the torch up or down as needed.
When you are done with a cut, you hit the stop button and turn it off, 
then move the eye to the beginning of the next cut, and hit start. It 
will also do straight line cutting in 4 directions- just turn it to the 
right direction and hit start.
It does require an operator, but I dont use it 8 hours a day- all three 
of us who work in the shop have gotten pretty good at it. When I need a 
bunch of something, I will often draw a big nest- say 20 or 40 parts, 
on one big piece of paper. It is amazingly quick to cut out lots of 
parts. I used to make a soap dish that we would cut 150 of at a time- 
one full 4x8 sheet of 16 gauge. Even manually running the machine, it 
was still a lot cheaper than paying someone else to plasma or laser cut 
them. I have big cardboard plan file boxes full of rolled up drawings 
from 12 years of having this machine- so it is easy to pull out a part, 
and cut a new one, 5 years after the last time you made something.
A fence I made with this machine is at this web site-
http://www.usc.edu/isd/archives/la/pubart/LAPL/grillwork/
100 feet long, 12 feet tall, mostly cut from 3/16" plate.
For an artist or small operation, I think a machine like this is much 
more practical than a full on cnc machine. It is really quick to make a 
drawing of a bracket or a circle, cut one out, and move on.
Plus, I dont have a lot of faith in the longevity of computer programs 
or hardware. It seems like I have to upgrade both every 2 or 3 years. 
New computers dont run old software, then I have to buy and learn a 
whole new one. This machine is simple, electrical and mechanical, and 
it has run well since 1991 with only the occasional overheated 
resistor.