Repairing a Broken "T-Brace"
© Frank Ford, 4/3/99; Photos by FF 3/28/99
This Dusty Strings "stave back" maple harp fell forward and suffered a broken wing. Actually, Dusty Strings calls this flat structural and decorative portion of the pillar the "t-brace."
It's a particularly nasty looking break, as the broken piece just springs away from the pillar:
The delicate rounded contour of the edges and the strong springy nature of maple make difficult to realign, let alone clamp back together.
First, in order to be able to align the parts perfectly, I actually glued on a whole lot of little spruce sticks, like so:
The idea is to be able to push the broken piece back just to the point where everything lines up. I glued the sticks on firmly because it takes quite a push to get the piece back where it belongs, and I wanted to make sure nothing slipped during my clamping operation.
My choice of adhesive for this job would ordinarily be clear hide glue, because it is very rigid, it doesn't creep even in heat, and because it wouldn't stain the maple. In order to have working time enough to clamp the hot hide glue before it starts to gel, I'd put the front of the harp into a little heat tent with my hairdryer:
Once I got the temperature up to around 100 degrees Fahrenheit, I'd have plenty of working time before things cooled too much. If you'd like more info about the hot hide glue and its applications, go to the Hide Glue Page.
For this repair, I chose to use epoxy because the piece had been separated a while, and had been scraped back into position repeatedly, so there were little flakes of wood missing from the crack. Hide glue wouldn't have the cohesive strength to fill the small gaps, and would have made for a weak repair. Because there's no place to add reinforcement without making the repair look ugly, I want to have maximum glue joint strength.
So, I mixed up a batch of epoxy and used my dry pigments to tint it to approximate the color of the maple:
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