[pianotech] CA for stripped screw holes

[John Formsma]

I know this is an old thread, but I had the opportunity to try this
technique today for the first time. It was on two stripped lyre top block
screw holes (for the screws that hold the lyre to the keybed.)

The reason I tried this was because it was quicker than drill and plug, and
it was a good test. The holes were roughly 5/16" in diameter and about 1
1/2" long. The original screws were 14 x 3" (I think I have the diameter
about right, but not 100% sure.). Took a section of "Shop Rag" paper towel
that was about 4" x 4", rolled it up, then twisted it so it could be more
readily forced up into the hole. Saturated the wadded up paper towel with
thin CA (Dryburgh). Then forced it up into the hole, using a piece of metal.
No accelerator. It cured really quickly, as what was sticking out of the
hole had to be cut off with a breakaway knife.

In my initial skepticism, I assumed this wouldn't work at all on a large
hole like this. But to my surprise, I couldn't get the screw started! Had to
drill it out (smaller bit, then larger bit). It held great -- very tight. Of
course, time will tell if this will work long term. But I feel very
confident this technique would certainly be fine for stripped holes that
don't have to support much of a load.

One interesting thing was that after the paper towel was drenched with CA,
it started "smoking" -- like what happens when accelerator is used.

FWIW,

--
JF



On Thu, Apr 23, 2009 at 11:40 PM, Tom Driscoll <tomtuner at verizon.net> wrote:

>  *List,*
> *A while back we had a thread on cures for stripped screw holes. I among
> others contributed the leather in the hole that I learned from the late
> journal tech editor Don Galt *
> *Another fix was mentioned where you plug the hole with a paper towel
> ,apply thin CA and accelerator. *
> *Well today I had a grand lid hinge that had been  repaired to death and
> failed again .The problem was in the top of the rim and the screws had
> pulled out of what was left. I filled the fissures -cracks and holes with
> the paper , added the CA and accelerator . Using the same screws they cut
> their way through and were TIGHT .It felt as if I had a proper wood to screw
> fit and they snugged right down .*
> * I'll try this on a Steinway action rail next. (like tomorrow as I have
> an old S and S on the docket)*
> *Film at 11.*
> *Tom Driscoll *
> **
>
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