Re: Re: abrasive wood?

Peter,

Good points, all. The forest products laboratory in Madison, WI, USA
has done EXTENSIVE work in this area. The mineral issue is very real
for SOME woods (like the KOA you mention, and TEAK) The oak is
breaking down the cutter by chemical reaction. The plywood and MDF
are breaking down the cutter two ways:

1) The heat of the cutting process(you said you guys use a thermwood,
so I assume you are going FAST. Good thing. FASTER is BETTER. Have
you tried vortex cooling? Big help.

2) The binder/glue/adhesive used in the material is generally much
more damaging to the carbide than the wood. It makes for
an "interrupted" style cut, like machining a rough casting. (In
addition to its' own hardness.)

The third major cause is chemical reactions between material and
cutter. (listed above)

And of course harmonic vibration, which the thermwood is designed to
minimise.

Hope this helps.

Ballendo

P.S. When NOT dealing with the above "composite" issues, HSS cutters
are still "sharper"(smaller grain size) and better for many solid
hardwoods!

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Very abrasive. Many hard woods have traces of mineral salts in them
(or so they tell me). We cut Koa, Oak and a few others and boy are
they hard on carbide. Treated woods are worse. We recently ran 8
sheets of fire treated plywood and wiped out a 1/2" two flute
straight cutter every two sheets. And this is Onsrud cutter stuff.
Not the brand X stuff. With those same cutters, I have cut aluminum
for many hours on a bridgeport. No sign of wear here. We have tried
to use disposable diamond but find it chips too easily when you
hit a staple, a small pebble or any other hard item plywood, MDF or
particle board often has in the edges. One day they will develop
something that has reasonable life in wood. Until then, we change
cutters at least every few dozen hours of cutting.
Peter
THRD, Inc.