[pianotech] Re Green piano bridge repair with carpet tacks

[Susan Kline]

It seems to me that if you've got a crack connecting a whole row of 
pins, you probably have a cheap piano and the owner will not want to 
spend a lot getting the problem fixed. Obviously, if you have a good 
expensive piano and the owner has the money to do the right thing, you 
will make a new bridge cap.

But, if you have a cheapo piano with a long crack through a row of pins, 
two ideas present themselves (at least, to me): (1) why is that crack 
there? Check the side bearing, and the angle at which the holes for the 
bridge pins were bored. (2) there is absolutely no reason I can see why 
you should keep the pins along the line of the crack. Move to new wood, 
changing the angle and the placement to put less stress on the pins 
(while still, of course having SOME side bearing.) You can always take a 
chisel and carve out a new notch if necessary, before installing the 
bridge pin again.

And I have not, to my knowledge, used epoxy on a bridge repair which 
failed. And I've done some doozies. Nor did I use fancy epoxy. Straight 
ordinary old five-minute from the hardware store has always done the 
trick. The only reason I can see for an epoxy repair to fail is if one 
left the pins along the crack, or if one encountered excessive side 
bearing and didn't correct it -- or if the wood of the bridge body is 
completely degraded for some reason, like having been soaked right 
through, or having been infested by powder post beetle. In that case, 
you probably have a lot more problems than just a bad bridge cap.

By the way, your repair with the headless steel tacks (cute, really) 
resembles one of my "bridge confessions" repairs, pre CA era, where I 
just wedged bits of toothpick or popsicle stick to get the bridge pins 
back to where they had even a little bearing. Now that one -- I see no 
reason to think that repair held up over time. It's a long time ago, a 
different city, never heard from them again. I added no glue, either. I 
was pretty young in the business.

Susan Kline


On 11/11/2010 8:03 PM, Douglas Gregg wrote:
> I have had two bridge repairs fail. Granted, in both cases there was a
> crack connecting the pins allowing a lot of movement. I used 2 ton
> epoxy with one with no filler added. The other was repaired with PC 11
> filled epoxy. However, if I used a filled epoxy again I would use JB
> weld that contains iron filings. It would have to be wormed up a bit
> to get good penetration.
>
> My point is (pun intended) that if you use the carpet tacks with the
> head removed as steel wedges, it works really slick. You don't even
> have to take all the tension off the string. I push the steel wedge
> shaped tack in next to the pin with pliers and finish by tapping it in
> with a punch until it is flush. If it does not move over enough, use a
> second one. It is so tight at that point that you can use any glue you
> want or none at all. You have to try it to see how neatly it works. It
> is a lot less messy and you don't have to tip the piano on its back
> either. I little CA glue would be fine and would wick in around the
> tack if you are worried about it moving.
>
> This is how I have repaired several bridges and it takes about 10
> minutes. Can't beat that. Five minutes to put in the tacks and 5
> minutes for CA or 5 minute epoxy. A few minutes to retune.
>
> Doug Gregg
> Classic Piano Doc
> Southold, NY 11971
>
>