Pinblock Drilling Centering

[Phillip Ford]

> >I'm unclear as to how you're drilling twice
> and maintaing your accuracy. 
> >That would depend perhaps if the block is
> drilled in the piano or out?
> >            Dale E.
> > 

> I don't know that it matters one way or another
> whether it's in or out of 
> the piano. Machinists proved long ago that
> drilling slightly undersize and 
> reaming to final size produced more uniformly
> accurate holes than drilling 
> a single pass. Trying it for myself, I got
> similar results with the 
> pinblock. Accuracy isn't maintained, it's
> increased. It really does work.
> 
> I've heard plenty of good things about pin
> driving fluid, but haven't tried 
> it...
> 
> Ron N
> 

I used what I now refer to as Ron's two bit method on my last pinblock and was
very happy with the results.  This is the way that I'm doing it from now on. 
Dale, are you worried that the second bit won't be exactly centered on the
hole of the first bit?  I drill out of the piano at the drill press.  I find
that the second bit wants to center the hole to itself.  But, you're taking
off enough on the second pass it probably wouldn't matter if the holes weren't
exactly concentric.  It they weren't then the result would be that the final
hole location would be slightly off from where you marked it, but it seems to
me not enough to make a difference.

I've also heard enough good things about pin driving fluid now that I want to
give it a try.

Phil F