Fix a Torn Tenon

While I assembled a Scottish-inspired stick chair this week, I struck one of the wedges at a bad angle. This caused half of the tenon to snap off. Worse, the damage occurred about 1/16” below the surface of the chair’s armbow. It left a giant crater that couldn’t be planed away.

The funny thing: I smiled after it happened.

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After 17 years of building these stick chairs, I enjoy making an occasional repair. It’s an opportunity to think, mess around a little and maybe even make the problem worse. Here’s how I dealt with this torn tenon.

Two Options

When this has happened in the past, I have drilled out the entire top of the tenon with a Forstner bit, then filled the hole with one of the pieces of waste left from sawing the tenon flush. This works great if you can find the center of the tenon.

In this case, however, I decided to excavate only the torn section of the tenon with a chisel and a gouge. Then patch the half-circle with waste left over from sawing the tenon flush.

The How-to

The first step was to chop out the torn section of the tenon. I did most of the work with a 1/8” chisel and a gouge with a tight sweep. The goal was to get the bottom of the hole as flat as possible and to leave just a sliver of the original tenon on the walls. I also deepened the hole from 1/16” to 1/8” to give the patch some more wood to grab onto.

Then I took the broken waste tenon and sawed off the broken section. I clamped the waste in a handscrew and used a flush-cut saw to remove the torn section. This created a plug with a flat surface that would meet the flat bottom of the hole.

I put some hide glue in the hole and tapped the plug into the hole. It took about five good taps, but the plug seated flat and squeezed out a good bit of glue. The whole repair took about 30 minutes.

— Christopher Schwarz


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