Re: Build CNC Plasma cutting Table

I know what you're talking about by the 4 slots. That is not a true drag cut torch. My Hypertherm is designed so the torch tip is in contact with the material. Because the tip is in contact there is no slag on top of the material at all.

On thin material, up to 14ga or so, I can pierce anywhere on the sheet with no slag on top of the cut. On thicker material, I do get a little slag at arc start if I start in the middle. This is not really a big deal because the lead-in contour takes the arc start. By the time the machine ramps into the actual cut line, the torch is lit, pierced and running at 1 - 2" per second, depending on material thickness and type. It will cut thin aluminum at 3" per second.

I've been drag cutting with this Hypertherm machine for a couple of years now and I change tips maybe once a month.

The machine I had prior to this had a cup with 4 slots. The cup is designed to hold the tip away from the surface a specific distance. By holding the torch off the surface, you will get slag on top of the material, particularly when the arc starts and you will probably have problems where the cup wants to hang up on previously cut areas.

With a drag cut torch, there is so little surface area in contact, hanging up is not a problem. If you got close enough to a cut edge to hang up, you would probably be running off the edge. A 2 axis machine might have a problem, but on a a three axis machine, you retract the Z axis before making any rapid travel moves. When you arive at the approach lead-in for the next part, you drop the Z axis back to zero, light the torch, pause 2 seconds and cut the part.

You should go to your local welding shop and try out a nice drag cut machine. Once you do you'll never go back.

Ross