In Part II I clamped a mould into the oversized hole and filled the gap in with JB Weld. Now it’s time to clean things up and finish the job. First I gently bonked the top of the mould with a rubber mallet to break it loose — recall that I waxed it beforehand so this wouldn’t require much force.
That done I could just twist the mould out by hand.
Next, I cleaned up the excess JB welt with a double cut bastard file. I originally started with a finer file but found it gunked up too quickly. Even with the bastard file I had to clean it out repeatedly with a file card.
And here’s how it looked when I was done filing:
Just for the heck of it I did a quick surface prep and sprayed on some gold leaf to prove to myself the repair would look good when I refinish the plate.
Much improved, I would say! The dimple is from a spot where the epoxy sunk down a little too low — I’ll probably fill it in before the full refinish job, but it will be hidden underneath the washer anyway.
Thanks for reading.
In the previous segment, I decided to glue some dowels into small bits of plywood to create a mould for filling in the plate holes with epoxy. Next, the moulds got a coating of paste wax so the epoxy wouldn’t stick to them:
Now, how to get these things located exactly? The hole in the washers is too small for them to poke through, so I grabbed a cheap washer of the same size and reamed it out with a 7/16” drill:
Now I could line up this reamed out washer with the circle I’d drawn around the real washers, and poke the dowel through it:
Then, clamp the base in place:
So before I go mixing up epoxy, I try to get everything ready to go. As for the choice of filler, a “cold weld” epoxy was a pretty obvious choice (JB Weld is what I had handy). It’s quite strong, and will look good when painted over with fresh gold leaf. JB Weld has a pretty long open time, but it’s always better to be prepared. My main applicator was just a piece of stiff poster board cut to shape and gently folded down the middle. I also grabbed a small piece of steel (cut from a windshield wiper spring) for “detail” work.
With the pasteboard I could scoop up a glob of epoxy and let it flow down into the hole. The small piece of steel was useful for pushing the epoxy down into narrower gaps. At this point I also gathered up my safety equipment — disposable nitrile gloves, a respirator, and goggles.
I used a kitchen digital scale to measure out equal amounts of the two parts. Note that when mixing any epoxy it’s important to keep the proportions as exact as you can! Otherwise you end up with unreacted material and thus a weaker bond.
To be continued in part III.
Welcome! I will be using this blog to share stories about my day to day work, and tips for technicians and piano owners alike.