Tuning pin choice

[Ron Nossaman]

>I was using this technique also, then did some testing with a parabolic bit.
>Several dozen holes were drilled  into multi-laminate rotary cut stock with
>the double pass method with jobber bits.  The second pass removed
>approximately .020".  Then a few dozen holes were drilled in the same
>material with a parabolic bit.  Miked pins were driven into some of the
>holes followed by a series of turns on the pins to simulate restringing,
>minus the string.  One could not tell/find the difference.  The remaining
>holes were sawn open and examined under magnification.  Wood fibers had
>nearly identical cuts  with almost no tearout and almost no surface glazing.
>The parabolic bit ran cooler, took less power,  and could not be loaded with
>chips through the 1 3/8" stock  Pins were tested several months later, again
>no difference could be felt.
>The bits are available form machine shop supply companies.
>
>Paul Chick

Try the same thing with Delignit, and there will be a considerable 
difference between single and double pass drilling. The extra dense blocks 
is what the two bit approach is intended for.

Ron N