Stickman42
Well-known member
Running a Challenge MS5 drill press. Drilling perfect bound books, 40/50# uncoated offset with 10 pt. C1S covers. Drilling format calls for 5 holes: four of them with a 5/16" hole, and a 9/16" hole in the center of the row of holes. The 9/16" drill bit is getting plugged almost immediately. Have sharpened the bit and replaced with a new one. Same result. Using a wax pencil on the outside of the bit as well. The bit is "standard", not one with nubs inside that supposedly keep the bit from plugging (CHT type maybe, have tried this also). Any suggestions?