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Countersinking #6 flathead screws into 0.060"

rockitdoc

Well Known Member
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So I would like to use countersunk flathead machine screws to attach my 0.060" panel. But, using a No. 6 countersink bit on 0.060" creates chatter as the bit gets deep enough to allow the screw heads to be flush. The result is a sloppy countersink. Is there another way to do this besides using thicker AL?
 
So I would like to use countersunk flathead machine screws to attach my 0.060" panel. But, using a No. 6 countersink bit on 0.060" creates chatter as the bit gets deep enough to allow the screw heads to be flush. The result is a sloppy countersink. Is there another way to do this besides using thicker AL?

Chatter usually happens at high tool speeds.

Use a 3 flute countersink bit or single hole debur tool in an electric screw driver (RPM < 100).
 
Im guessing that as the hole opens up it is becoming bigger than the pilot tip of your countersink bit. Put a wood backing plate with a correctly sized hole for the pilot tip under the panel so that the bit stays centered when drilling and see if that corrects the problem. If not, try a different type of countersink bit, maybe one with a single flute.
 
Hold a back up piece of metal 1/16 or 1/8 thick drilled to accept the pilot of the CS bit behind the panel hole as you CS the panel. The CS tool will be stabilized by the back up not allowing the tool to wobble in the panel.
 
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