[pianotech] snapping pins

[Douglas Gregg]

In response to the question about swabbing a pinblock hole with epoxy,
I can offer a couple suggestions. Epoxy formulas vary widely, of
course. The 5 minute epoxies tend to be quite rubbery and will have
more tack on a sliding surface. They also cannot easily be faired with
sandpaper for the same reason. The thin tapered edge with tend to grab
the sandpaper and peel up. The addition of fairing microballons will
help for this problem.

Slow setting epoxies tend to cure harder and are less likely to bind.
Even better for the pinblock application is filled epoxy such as JB
Weld or Marine tex black or other epoxy steels. I have used JB Weld to
fill  several tuning pin holes where the pins could slop around in the
hole and could be taken in and out. They were so sloppy that I had to
prop the pin to the correct angle while the epoxy cured for 24 hours.
I waxed  the pin with paste wax to prevent it from being locked solid
by the epoxy. They tuned like a new pin in a good block. The key is to
have a hard epoxy that the pin will not grab due to  excessive static
friction. This is also why CA glue works as well as it does. It gets
very rigid when it hardens and does not have the tendency to have a
lot of static friction and grab and release the pin as it is moved.

Has anyone tried any of the pinblock treatments for pins that are
jumpy. I have considered this but not tried it. Even CA glue might
work. It seems counter-intuitive to add CA glue to a jumpy pin but it
might give the soft epoxy or even just tight wood  a hard surface that
would then slide more smoothly. Just a thought.

Doug Gregg
Classic Piano Doc