Drilbert, We used to have this problem from time to time. Believe it was almost always related to static. You may want to review your vacuum static dissipation lines, from the spindles all the way back to the collection system. We ended up with a braided ground wire around each of the spindle dust tubes, and a direct earth ground at each drill & router. Maybe overkill, but this seemed to knock down our problem. Greg Anderson Adv. Mfg. Eng. GE Fanuc Automation ---------- From: drilbert[SMTP:[log in to unmask]] Sent: Tuesday, September 02, 1997 10:11 PM To: [log in to unmask] Subject: [TECHNET] missing hole defects We have experienced an intermittent missing hole (not drilled) defect on one part number. On each of 20 panels I have analyzed, the same hole is missing. The entire drill file is intact on the mainframe, however, some kind of glitch must be occurring either during downloading the data across the DNC or executing the program on the drill machine. We use Hitachi drill machines. Has anyone run across such a problem, or does anyone have an idea what might be the cause of this mystery? drilbert