PP 50 shielding cup.

[performance]

Powercat, It depends on how bad it is. Its not a cut and dried issue. But what I suspect is you have 1) improper technique and you are trying to pierce straight down. Lean the torch at 35 degree angle and slowly stand it up. 2) You are exceeding the piercing capacity of the torch. If you are trying to pierce over 1/2 of the units quality cut rating, you are exceeding the piercing capacity. 1/4" is the thickest I'd recommend doing regularly. 3/8" is possible, but doi it slowly.

[Steve]

Powercat, It depends on how bad it is. Its not a cut and dried issue. But what I suspect is you have 1) improper technique and you are trying to pierce straight down. Lean the torch at 35 degree angle and slowly stand it up. 2) You are exceeding the piercing capacity of the torch. If you are trying to pierce over 1/2 of the units quality cut rating, you are exceeding the piercing capacity. 1/4" is the thickest I'd recommend doing regularly. 3/8" is possible, but doi it slowly.

I am curious then as to how the CNC tables can start a cut straight down in the middle of a piece without having the cup covered with material?

Could it be the water that is usually on top of the material stops the blow back?