Handheld Plasma Cutter with CNC?

[Jim Stein]

I have a Hypertherm 380 hand held plasma cutter and I also have a homemade CNC Router. The controller I am useing is from stepperworld it is the FET3 Cruiser package.It is running at 12 volts.I figure it can go about 14 ipm max the way it is settup right now.

My question is this:Is there a way I can use the handheld torch with my current settup.How do they normally start the torch on a plasma CNC?I have the ability of turning the spindle on through the program, could this be used to start and stop the torch?I know I would need a THC.I have read that most CNC plasma cutters are water cooled.Could I get away with not being water cooled.I do not know if 14 ipm would be fast enough,but I could step up to 36 volts.That should get me about 28 ipm.I guess I could even go with a 10 tpi lead screw if I had to,that would get me 40 ipm.

If anyone has any tips or information I would greatly appreciate your help.
Thank You:Jim

[Al_The_Man]

On a Plasma unit that has a CNC option, it is started by a contact closure at some point, so you should be able to do the same thing with simulating the torch switch.
You can get away without water cooling as long as the duty cycle is not high i.e. your off time is longer than the on time.
Usually the sequence on a CNC unit is the pilot arc is initialized and once transfer is made to main arc, motion commences. Also automatic height control usually comes in once the travel has started to avoid the torch diving through the initial pierce. Your travel feedrate depends on your available current and material gauge. You should get an idea what your torch will do when you cut by hand. e.g. I believe 200 amp comercial units run at around 100"/min for 1/4" ~ 3/8" plate.
Al

[InventIt]

Defiantly would need faster speed. 40ipm would work good for most stuff. BTW, what thickness material would you be cutting and how many amps is that hypertherm? I run a Miller 3080 at about 40 amps and 40 - 45 ipm for 1/8" steel.

For light use, I made a holder for the hand held torch that uses a micro switch to activate the arc. No THC, holder just "floats" over the material. Works good.

[Jim Stein]

My Hypertherm is 27 Amp max with a 35% duty cycle @ 27 amps.The recommended material is 1/4 the maximum is 3/8, but it will rough cut 1/2 very slow.Most of the material I will be cutting will be 3/16 or 1/4.Some times I might cut 3/8,but not very often.

InventIt
How does it just float over the material? What happens if the material starts to warp?

THANK YOU FOR THE HELP.
Jim

[InventIt]

Torch holder is held to Z axis by a small linear bearing allowing it to freely move up/down as the material moves. Also, the switch is hooked to this torch holder so when you plunge the Z axis down to the material the switch activates the arc. It works ok for light duty use. THC would be a better soulution for a machine used more often.

[Alex S.A]

Hi Jim,
If the marterial warp, it can broken the torch when the equipment is mechanized. I think this will hard to happen because in plasma cutting the ZAT is smaller than in oxy fuel cutting. What you have to pay attention is the duty cycle when you cut 1/4 and 3/8. The quality of cut will be affected. The cut of 3/8 will be just to separate the materialand the cut of 1/4 and 3/16 will be ok.