[pianotech] Pinblock cracks; CA or Epoxy?

[Joseph Garrett]

David B. said:
"A client's old birdcage piano has some splits in the pinblock. He is 
strongly committed to keeping it as it's in a house which belonged to 
his grandparents and which he has restored, and the piano may have been 
in the house since the house was built. 
Would it be a good idea to put epoxy, or CA glue into the splits, of 
which there are severat, about two to three inches long and varying in 
depth from 14 inch to 3/8 inch. Which would be better? CA or epoxy?
 Best regards,"
 
David<
Those type of cracks are common on English Overdamper Pianos, (the correct
term for those "Bird cage things"<G>). It indicates the type of
pinblock/frame construction, which is blocks of hardwood Butt Jointed with
Hide Glue. The glue joints are failing. CA glue does not do well with
Shear, whereas Epoxy does. I would suggest Epoxy. The technique I have used
successfully in similar situatons is: Heat the surface of the crack areas
with a heat gun, etc. Use the thinnest type of clear epoxy you can find.
West systems is good for that. There are better ones, but can't think of
them at the moment.<G> put the Epoxy in the cracks with thin spatuala or
artist's pallet knife, while continuing the heating of the area. This is
best done by two people, btw. One heating and the other speading and
stuffing the epoxy in the cracks. Give it a full 72 hours of set up time,
then proceed with tuning. Should be just fine. (albeit not very pretty
sometimes.<G>) I do not recommend cleaning up the excess with lacquer
thinner or acetone, as that will diminish the strength of the epoxy, in my
experience. DAMHIK!
best,
Joe

Joe Garrett, R.P.T.
Captain of the Tool Police
Squares R I