pinblock drill size

[BSimon1234]

Someone mentioned;

<<If you are using the 12-ply block, I have the best luck using .257 bit. With
a 2/0 pin, this is drilling .025 undersize.  This has given me around 125 inch
pounds of torque for several years now.>>

I don't think anyone has mentioned it, but I have found that one factor that
causes the great variance in pin torque is - how the hole is drilled. 

I guarantee that you will get different pin torque, using the same drill and
block, if you are hand drilling as opposed to using a drill press  or a
portable drill press set up in the piano. Try it on a piece of scrap pinblock.

Also, sharpness of the bit is important. A dull bit will give different torque
than a sharp one of the same diameter. A dull drill might be just fine if you
know what you are doing and it gives the right torque. Again, try it out on
scrap.

Here is a pet peeve - Pin bushings. Most technicians say they add nothing to
pin torque. I think that is more or less true if they are used as drilling
guides and a pin sized hole is drilled through them. If, however, you can
drill the pinblock and then install the bushings and string, they add a lot of
torque for many years. And the top of the pin is better stabilized where it
needs to be.  

Try an experiment. - Next time you have an old upright with  about zero pin
torque, one where you can pull the pins out with a vice grips without removing
the string, pull out a pin, remove the old pin bushing, install a new one, and
put the pin back in through it.  You should just be able to tune that note.
(temporarily) It can add 20 inch pounds of torque.

I know some manufacturers never used them, and I don't like tuning those
pianos as much.   If not drilled out, I think they also help "seal" the
pinblock against rapid humidity changes and the job looks better.

Bill Simon
Phoenix