Interesting,,,
I have done the unison patch with West Systems epoxy and their graphite filler. The filler is used for air foiling hydroplanes. The lack of friction and the compressive strength of steel seemed to be what was needed to prevent the wire from indenting the cap too deeply and adds strength at the pin.
I also think the hardness would transmit the vibrations more efficiently
I wish I had done the whole cap like this one. I painted the cap and then notched. The resulting dust tainted the wood.
Maybe the cap was not replaced. Perhaps the original cap was coated to fill the wire depressions and build the cap back the mm that was lost. Then drive in new pins with epoxy and finish the notches too.
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Keith Roberts
owner
Hathaway Pines CA
209-728-2163
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Original Message:
Sent: 09-23-2018 12:47
From: Robert Callaghan
Subject: Black bridge cap
I've never seen a black bridge cap before.