Q & A: Why did my dovetail bit break?

Q:

I’ve snapped off the tips of my dovetail router bit twice now
while cutting sliding dovetails in hard maple. I don’t want to get
burned again. What am I doing wrong?

A:

A dovetail bit does indeed have fragile tips.A full cut in hard maple
puts a lot of stress on them.Usually you can deepen a router cut with
successive passes of the same bit, but the shape of a sliding dovetail
doesn’t allow that.

You can relieve most of the stress on the bit’s tips by removing wood
from the groove with a straight bit first. Pick a bit that’s slightly
smaller than the narrowest part of the dovetail groove. Then rout a
groove that’s 1/32-in. or so shallower than the final groove. Now
your dovetail bit has very little work to do in finishing up the groove,
and both you and your bit will experience less stress!

Click any image to view a larger version.

Give your dovetail bit a rest. Pre-plow a
straight groove to remove most of the wood.

This story originally appeared in American Woodworker February 2001, issue #85.

February 2001, issue #85

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