The Care and Feeding of Pinblocks II

After the simple mechanical repairs mentioned in the previous article have been tried and failed or for some reason inappropriate there are a number of chemical based solutions.

 The easiest and usually the safest for a first try would be an application of cyanoacrylate (CA glue).  Before application, the action should be removed from the piano if it is a grand or the piano should be tipped on its back if it is a vertical.  In the case of the grand, cover the keybed with newspaper before applying the glue.  I would not expect any glue to work its way completely through the pinblock yet if it did . . .

I would plan on a minimum of 2 oz of thin viscosity glue to do one piano, some may take more.  Be sure to work in a well-ventilated environment as the fumes can build very quickly and are not pleasant.  I also ask about respiratory problems anyone in the home may have.  If this is an issue you may want to ask them to leave for an hour or two.  I touch the glue dispenser to the tuning pin just below the coils, this allows the glue to run down the tuning pin without necessarily coating the entire tuning pin field. 

The glue is very thin and will wick into the pinblock.  If tuning pin bushings are present the treatment may be less effective.  Often there will be a slight opening on the back side of the pin where the pin has been pulled towards the back by the string, apply the glue here so that is will run down the pin through most of the bushing.  The glue will form a layer around the tuning pin essentially glue sizing the hole.  You can usually tune the piano within a short period of time as the glue sets up pretty quickly.  Give the room a few minutes to air out and get to work.  If some of the pins are still loose, reapply the glue and come back another day.

In situations where supper glue won’t work and for whatever reason oversized pins are not acceptable I have used various epoxy and epoxy like products to resize the pinholes in order to use standard sized pins.  LakeOne Wood Rebuilder is one product I have used.  I once used it on any entire upright pinblock.  Swab a fair amount of the material into the tuning pin holes and ream to the appropriate pin size when the material is dry.  Do some trials first to establish most effective reamer and pin size for your particular situation.  I have also used a variety of epoxies and have had similar results.

In verticals you must be careful about material gathering in the bottom of the hole, which would interfere with driving the new tuning pin. (Voice of experience.)

While this solution will actually go a long way to restoring a pin block to a useable torque, the labor involved with doing an entire block would be better used to replace the block, even in uprights.  If things are so bad that you will be treating the entire block, for very little extra cost a new block could be installed.  It is best used for isolated pins.