Shortening boards with already dry-fitted joints

This post is on using scarf joinery to shorten boards with already fitted joints, using 1:2 joint lines instead of 1:8 – 1/10; and the benefits from loose tenons in enhancing joint strength, preventing the introduction of warp, as well as at attaining the desired length.

With only a memory from Terrie Noll’s “The Joint Book, The Complete Guide to Wood Joinery” (ISBN 91-534-2490-5) of what seems to be an utterly challenging scarf joint (please, see drawing), I went ahead.

Failing at getting a tight joint line by edge planing, and having to add a piece, I used a temporary “shooting board” (please see photo). That did the trick, particularly on the second rail. Probably, it would have been a more challenging task along four times longer edges.

Assuring the desired lengths could have been lot easier with the use of masking tape, but that only dawned on me when editing the photos. The contraption used is depicted.

By gradually turning the screws of clamps along the axes of the rails, the desired length was established. F-clamps from the sides prevented sliding – widths had to be maintained

The second joint line looks a lot better. Actually, enlargement of the photo showing the finished results may be required to see it. Number one will go to the bottom back of the cabinet, away from any critical eyes. A more forethinking woodworker would of course have learnt from a prototype…