We have been grinding a LOT of pilot-points on standard 3/32" HSS drill bits (Viking drills). The pilot tip is .25" long, ground down to 0.052" (straight ground shoulder, nothing fancy).
We have a KO Lee tool and cutter grinder with an added on auto-feed (guess that would be "y", perpendicular to the table), K60 wheel. We're using a converted a hand-spinner (they type with no bearings, just the spindle in case-iron sleeve) with a motor, and are gripping the bits near the tip with a standard 5-c collet.
This grinding aspect seems to be working pretty well, but the work-holding equipment is causing some issues. I was inquiring if some of the grinding experts here had any suggestions for better work-holding and spinning to grind the pilots. It seems that clamping on the flutes near the tip with a 3-tine standard 5-C collet produces some runout issues, particularly on the random bit that is chucked "just wrong" in orientation. I'd like to use a better spinner than the converted indexer, like a Harig, but these are chunky and very difficult to get near the wheel with a bit chucked near the tip.
Any suggestions on holding these 3/32 bits for pilot-grinding would be appreciated. For example, would a custom 2-tine extened-nose collet for the bits, in a ball-bearing spinner work better, or does anyone know of a compact spinner with an extended nose, etc. Or should bits be held by a different method altogether. (Also, if anyone is interested, or knows a source for doing this sort of work, feel free to PM me, we're using at least a couple hundred of these a month, and are looking to outsource it).
We have a KO Lee tool and cutter grinder with an added on auto-feed (guess that would be "y", perpendicular to the table), K60 wheel. We're using a converted a hand-spinner (they type with no bearings, just the spindle in case-iron sleeve) with a motor, and are gripping the bits near the tip with a standard 5-c collet.
This grinding aspect seems to be working pretty well, but the work-holding equipment is causing some issues. I was inquiring if some of the grinding experts here had any suggestions for better work-holding and spinning to grind the pilots. It seems that clamping on the flutes near the tip with a 3-tine standard 5-C collet produces some runout issues, particularly on the random bit that is chucked "just wrong" in orientation. I'd like to use a better spinner than the converted indexer, like a Harig, but these are chunky and very difficult to get near the wheel with a bit chucked near the tip.
Any suggestions on holding these 3/32 bits for pilot-grinding would be appreciated. For example, would a custom 2-tine extened-nose collet for the bits, in a ball-bearing spinner work better, or does anyone know of a compact spinner with an extended nose, etc. Or should bits be held by a different method altogether. (Also, if anyone is interested, or knows a source for doing this sort of work, feel free to PM me, we're using at least a couple hundred of these a month, and are looking to outsource it).