What’s the best way to ramp a 5/16 (.3125) inch hole for inserting a carriage bolt in CC Pro? I tried a contour TP with no offset using a 1/4 inch bit. Is this covered in a tutorial?
Don
If the hole is designed at 0.3125, you want a contour path with inside offset.
If you have ramping, set your DOC to something deeper than the hole so it only makes one pass at the bottom, then set your ramp to something like 5° so it spirals (Helical) down to the bottom depth then makes one pass around the bottom. This is called Hole Milling and works best with a tool that is just a bit larger than 1/2 the hole diameter. In your case, a 1/4" tool for a 5/16 hole is OK. A 3/16 tool would be perfect.
If it were a higher tolerance hole, like for a dowel I would make a 9/32 hole, or offset the 5/16 vector inward 0.005 - 0.010 and hole mill that to rough it out, then hole mill the 5/16 hole to get a nice clean accurate hole. This is a clearance hole, so one pass should be fine.
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Thanks Tod. That’s just what I needed.
Tod,
I started with a 5 degree ramp, then tweaked the diameter of the hole, then went up to 10 degrees and now it is perfect! Thanks for your help on this.
Don
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