[pianotech] pinblock drilling clamp

[Ron Nossaman]

Mike Spalding wrote:
> Wim,
> 
> The problem you have solved is not the problem I was having.  During the 
> second pass, when the .257 drill enters the .219 hole, it can grab and 
> lift the pinblock at any point during the feed, not just at the end when 
> it penetrates the bottom of the block.  By clamping the block securely 
> during the entire stroke, not only is this grab-and-lift prevented, but 
> any random shifting of the pinblock that might make the hole slightly 
> larger is also prevented.

Mike,
A couple of things; The diameter difference I use between 
first and second pass is 0.018". Yours is 0.038". I'd 
recommend something more along the lines of a B or C, or 6mm 
for the first pass. The more wood you remove on the second 
pass, the less effective the two pass approach is, and the 
more likely the second pass will grab and burrow. The other 
point is the type of bit used. A high spiral bit on the second 
pass is the kiss of death, and pretty much guaranteed to grab. 
Regular old non exotic jobbers bits work nicely. You don't 
even need to cool the drill.
Ron N