plate plugging

[Farrell]

To plug a hole in a cast iron plate, I recommend West System resin thickened with their # 404 High-Density Filler. The "404 High-Density filler is a thickening additive developed for maximum physical properties in hardware bonding where high-cyclic loads are anticipated. It can also be used for filleting and gap filling where maximum strength is necessary. Color: off-white."

http://www.westsystem.com/

When using epoxy on metal, it is recommended to sand the metal rough (maybe run a small round file around the inside of the hole perimeter). Then apply some unthickened resin and hardener and sand it into the metal surface - this provides an excellent "bite" for the epoxy into the metal (maybe roll some sandpaper around a small dowel and sand inside edge of hole). Then fill the hole with peanut-butter-consistency thickened epoxy. Sand smooth after a day or two. You will have a repair that will not shrink, crack, or separate from the cast iron. The only way you will see the repair is if you don't smooth out the rest of the plate like the repaired area.

I have used this stuff on cast iron keels on sailboats to fair the keel ballast surface (only I used a lighter-weight filler because of all the anticipated sanding). When the metal is properly cleaned and sanded prior to epoxy application, and then the epoxy resin is sanded into the metal, the epoxy becomes part of the metal. I have never seen this fail - even after years submerged. And that is important if you ever want to make a mooring out of your plate. .........what kind of piano did you say this was?

Terry Farrell
  
----- Original Message ----- 
From: "David Foster" <pno2nr@hotmail.com>
To: <pianotech@ptg.org>
Sent: Monday, April 08, 2002 6:17 PM
Subject: plate plugging


> List,
> 
> When tuning yet another Steinway grand with a loose A-0 tuning pin, I was 
> daydreaming about ways this problem could be corrected during rebuilding.  
> It seems to me that the reason behind the problem is that the tuning pin is 
> way too close to the flange edge of the block.  I thought that reconfiguring 
> the pattern of the lowest four tuning pins to be staggered instead of in a 
> straight line would fix things just fine.  Well, drilling new holes in the 
> plate before regilding would not be that big a problem, BUT...   How, or 
> with what do I plug the original holes?  I would prefer the original holes 
> to really  "disappear" for cosmetic reasons.
> 
> Has anyone done/thought about doing this?   And, does anyone else think this 
> would be a good thing to do?
> 
> Dave Foster
> 
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