McGuire Piano
Occasional Sales of Restored Pianos by

Duane McGuire, RPT

Knuckle trimming

Category: Shop Procedures

Knuckle trimming! I was pleased with the way this worked. I'm replacing knuckles in a 1918 Knabe. The shanks at the knuckle slot are 11.0 mm +/- 0.1 mm wide. The Abel knuckles are 11.7 mm +/- 0.1 mm wide. I made this sweet little jig to trim the knuckles to a width of 11.0 mm. (modern shanks e.g. Renner measure 11.7 mm in width)

11.7 mm knuckles on the left.  11.0 mm knuckles on the right.

The trimming jig.  The screw at the bottom of the bore allows for micro adjustment.

Ready for trimming

The jig set in the stopped miter gauge.

0.7 mm shorter.

The process

 Context:   11 mm knuckle below.  11.7 mm Renner parts above.

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