What are you using to generate the cut files (CAM)? You need extra delay on the pierce and make sure your workclamp is on a clean section of the actual material. You need max current flow to pierce 1". Typical rule of thumb: you can pierce (with a 90 deg straight pierce) about 1/2 of the max cut rating of the plasma torch. If it lists 1.5 inches as cut max it will only pierce about .75 cleanly. At 1" and greater the trade-off between plasma and oxy-fuel cutting starts to narrow.