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The Chair – Sawing Tenon Shoulders on the Curve
My previous report on the chair build was aimed at determining the correct position for the mortice - and also whether the tenon shoulders were square across the upper and lower sides.
I had used templates to mark out the plan shape of each (front and rear) curved stretcher, however the shoulder angle of each tenon was gauged by eye. That is not the most reliable method (parallax and all that).
To my eye there was something definitely wrong.
I used the wooden hand screws to square up the shoulders. Here's how ...
Firstly, this is the curved stretcher (it is a compound curve, curving in two directions). There is no way one can simply use a square or even a sliding bevel to determine the square as there is no reference flat area.
If I was to build a dedicated vise, the clamp/jaws would be narrow to minimise the effects of a curve. The hand screw here was sufficiently narrow for this task.
When clamped it made contact along both sides of each shoulder. You can see how much is to be removed.
Before sawing, ensure that both clamp sides are coplanar ...
Now saw with a flush cutting saw (no set to damage the clamp) ..
It may not look it here, but the tenon cheek was measured square to the shoulder on both sides ...
Regards from Perth