On 20 Jan 2007 08:36:35 -0800, wrote:

Yes I would expect surprises from spiral cutters, more on that:
At no.12 http://patwarner.com/faq.html

Reading your faq leads me to a question. First thing I cut using my
Incra jig many years ago was a box joint. Used a Freud straight bit
and the joint ended up not just loose but sloppy loose. I diddled
everything I could think of to get it tight and finally decided that
the bit was oversized. Went down to Coastal and they were out of
straight bits that size but had an Amana spiral. Tried that and the
cut was dead on. I've been using them for box joints ever since (and
since they're paid for quite a lot else).

Now, my question--all the straight bits I have seem to cut oversize,
the spirals don't. Is this an artifact of the different cutter
geometry or does Freud just make their bits oversized and Amana
maintain tighter tolerances?

I suppose I could just get some Amana straight bits to compare with
the spirals but the original Freuds are still in good shape.

****************************
J. Clarke wrote:
Was cutting a 3/16" wide dado in a piece of Lyptus using an Amana
upcut spiral bit. Was cutting 3/16 deep in half inch stock. Router
is a Porter-Cable 7518 in a lift.

All was going well, when, after cutting four pieces, on the fifth one
I'm about three inches along and all of a sudden the bit comes right
through the top--it's still cutting just decided to pull out of the
end of the collet. So I put it back, socked it down hard, and
continued the cut and three inches along it did it _again_.

This time I pulled the bit and the collet and cleaned both with
lacquer thinner and got a lot of black crud off both, but I'm pretty
sure I didn't get it all out of the collet. Whether the problem is
fixed I don't know--I only had two short cuts after that.

If I had been holding the piece above the bit then it would have gone
right through my fingers. The notion that there's wood between you
and the bit is false security.