Backpost delamination

[Mike Spalding]

Cy,

I'd say there's probably a delamination under the veneer.  (Is it 
veneer, or thin plywood?  If plywood, sometimes you can see splintering 
or delamination caused by the pinblock parts moving apart underneath)   
My preference would be to remove it with plane/chisel/scraper, rather 
than moisture, but that's 'cause I use 'poxy for the repair and I want 
the pinblock wood to be dry. 

Mike

Cy Shuster wrote:
> I tuned a 1980's Wurly studio last August, and brought it up maybe 40 
> cents to pitch.  I measured the pitch before tuning it this month, and 
> this is one time that measuring really helped identify a problem.  The 
> bass was maybe five cents sharp, but after middle C, it dropped off to 
> 80 cents flat.
>
> I use TuneLab for pitch raises, and as I got to about C5, I heard the 
> unmistakeable sound of wood fibers letting go with each movement of 
> the tuning hammer (torque was OK).  The bridges were fine, so I looked 
> over the top at the backposts.  Each one is made of three sections of 
> oak, and one joint had come unglued part way (about 1/4" deep):
>
> http://tinyurl.com/2rhoug
> (also see attachment)
>
> I've never heard such an immediate splitting noise in a backpost with 
> raising pitch (and there wasn't much overpull at this point).  I'm 
> concerned about the pinblock separating, too, but its top is covered 
> with veneer. What's the best way to unglue it to take a look?  Just 
> iron a damp cloth? Should I look for a plate crack, too?
>
> It seems that a couple three carriage bolts should do the trick.  I 
> could wick in some thin CA, too; I don't know if I could work epoxy 
> in.  Is there a better fix?
>
> --Cy--
>
>
>
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