Pinblock Drilling Centering

[Ron Nossaman]

>                Ron
>                I've always used the one pass method. Never heard of the 
> two pass technique till you brought it up.

Dale,
I never had either until I thought of it. At least not in the context of 
drilling pinblocks. Drilling undersize and reaming to final size is common 
machine shop technique.


>My sample holes and pin fit were borted at .250 for a no. one pin  and the 
>fit was good so I drilled the block this way. For no. 2's I use a .257.

For 2/0, I'm drilling 17/64" (0.265), or 6.8mm (0.267).


>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?

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.


>Either way enlighten me as I don't recall the details. The sample pins I 
>drilled were equal to the feel and smoothness of maple
>      I've also done some experimenting with pin driving fluids and found 
> I liked them. Drove a no'2 in a .250 hole swabbed with with Mckloskeys 
> varnish. It was scary for a couple of days and then it settled down to a 
> VERY nice smooth and solid feel. The no. 2 in the hole without varnish 
> popped and was too tight even after a week or more/still.
>            Dale E.

I've heard plenty of good things about pin driving fluid, but haven't tried 
it. I drill the block in the piano, and haven't been able to picture a 
method of getting the varnish into the block without spending half a day, 
getting it all over the plate and bushings, or both. If you get away with 
drilling Delignit that far undersize, with one pass, and get a good uniform 
pin torque that doesn't twist the pins off, it's probably because of the 
varnish. So tell me, how do you get the varnish in the block without 
getting it all over the plate? Maybe I'm just neatness challenged.

Ron N