Very happy with my purchase. However, I am having trouble cutting 1/4" cleanly. Anything up to 1/8" will cut very cleanly, with dross that just brushes off with your hand. Insanely good cutting.
However, as soon as I go to quarter inch, I get so much nasty dross on the backside that takes a fair bit of effort to chip off. I’ve reduced my cut speed because in some spots it would cease to punch through. However, I still have awful amounts of dross, and the edge geometry has quite an angle to it.
Torch appears to be square, best I can measure. Plenty of air, running at around 27 amps.
Miller 375 Xtreme, probably 100lbs air, 27a, running 18IPM.
On another note, my machine’s cut speed chart and what I’m actually cutting at are hugely different. Recommended speeds are WAY too quick, so I’m not sure if the crossfire is off, or the chart is off.
I am new to this, someone more experienced will be along soon but, I have found with my 675 ex the thicker I am cutting the better ground I need. On the thicker stuff with millscale I grind a clean area on the piece and put my ground right to it. This may not be your problem but it is something to check.
The cut charts for my machine are with a machine torch with extended consumables, it is a loose guide at best with the hand torches and drag shields.
Try slowing that sucker down to 70 or 80 ipm and see what happens, I just override the torch speed in Mach3 , try 40 or 50% and see what you get.
I have a different plasma but I experienced the same results and my issue was a warn electrode. A new tip but a partially warn electrode gave me terrible bevel and dross on thicker material. Just something to check…
ctgolfer, thanks for the info. I have been just clamping the ground to the bottom nut on the water table. I will grind a clean spot on a piece of quarter inch and try that.
By the way, currently running at 18 inches per minute. From everybody else on the forum, that seems extremely slow. Any ideas there?
DevilDog, I tried these cuts with brand new tips. I can only get a single size tip, but maybe I could drill out the end to make it larger? Not sure.
I cut some 1/2" ar500 plate today with almost the same results, much dross on the back, skipping in others, angled cut.
I cranked it all the way up to 40 amps, slowed it to 12 ipm and went over the same pattern to finish the piece.
Frustrating. Remember we are forced to cut with drag shields, Miller recommends 1/32" above the deck for best performances, the thin shim on our tables are twice that. I use a feeler gauge to set the heights.
