Pinblock Plugs

Overs Pianos sec@overspianos.com.au
Wed, 14 Mar 2001 08:37:11 +1100


List,

I can only concur with Rogers approach, we use West System for 
plugging. And while I have no doubt that the Weldwood would have 
sufficient strength, these glues will add a small amount of moisture 
to the repaired pinblock, whereas epoxies will not. This is an 
important consideration with pinblocks since, if an appropriate 
density of wood has been chosen originally, it will have an ADD in 
excess of 0.7 gr/cc. A pinblock repaired with a water based glue will 
take a long time to normalise. There is a small risk that pinblocks 
repaired with water based glues, might in time allow for the pin 
torque to reduce to marginal levels.

I agree with Del about the gap filling qualities of epoxies. This 
must be an important consideration for pinblock repair. Regardless of 
which adhesive is chosen, I would add that it is very important that 
the holes and the plug mating surfaces are lightly sanded prior to 
gluing. A pinblock drill hole will tend to have a 'burnished' inner 
surface, which will prevent the glue film from keying into the 
adjacent pinblock (I speak from past experience here).

The idea of using larger diameter plugs, where possible, has much 
appeal. Pinblocks often fail because the wood density is too light, 
and is therefore incapable of supporting the string tension. A 
smaller plug in a weak pinblock might result in the pin pressure 
splitting the new wooden plug, crushing it outward into the original 
pinblock material. I realise that a 15mm plug for example, will be 
too large to allow for all holes to be repaired in one session. But I 
suspect it will produce a more satisfactory repair.

Regards,

Ron O
-- 

_________________________

Website:  http://www.overspianos.com.au
Email:      mailto:ron@overspianos.com.au
_________________________


This PTG archive page provided courtesy of Moy Piano Service, LLC