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Homemade Router Jig for Tenoning.
- BY HAND - Using a tenon saw.
- CROSS CUTS ON CIRCULAR SAW TABLE - The tenon is cut by setting the saw blade to the correct height to remove the waste stock and making parallel cuts close together by moving the rail in towards the fence about 1/8" (thickness of the saw blade) repeatedly after each cross cut until the rail reaches a block clamped to the fence set at the correct distance in from the saw blade for the shoulder cut. The rail is then turned over and the process repeated on the other side. The height of the blade is then adjusted for the end shoulder cuts and the process repeated again. This process is not possible on some saws where the riving knife protrudes higher than the blade and cannot be adjusted downwards. On a saw where the crown guard for the blade is fixed to the top of the riving knife the process is only made possible by removing the crown guard which is not recomended as it involves breaking health and safety rules. This is a fairly slow method of cutting tenons.
ON CIRCULAR SAW TABLE - This involves parallel saw blades
(combination or rip
but not crosscut only) divided by a spacer on the spindle the same
thickness as the tenon. The rail is held vertically in a sliding jig
with a handle well away from the saw bade. The two blades cut the two
sides of the tenon accurately. Can also be done with single saw blade
by turning the rail after the first cut but accuracy will not be quite
as good as you will not be working from one face only or with a
fixed width spacer.
The shoulders have to be cut separately by other means.
- FIXED TABLE MOUNTED ROUTER - Using a bench mounted router with a fixed fence and sliding jig to push the rail over the router cutter at 90 degrees, if there is a lot of waste to remove, it is better to adust the cutter height up in increments of about 3 - 4mm rather than trying to make deep cuts in one pass. Shown on the right is my version of such a jig. In this case I cut the shoulders of the rails on the circular saw first to minimise break out of the grain at the end.
- PLUNGE ROUTER - The workpiece is held secure in the jig and the router is passed over the rail by means of a guide jig to cut the tenon.
- TENONER - This is more of an industrial method used in larger workshops or factories. A tenoner is in fact a spindle molder with dedicated set of cutters for tenoning and a sliding table to which the rail is clamped. The tenon has both sides cut with one pass and it is therefore a very fast and efficient process. The one drawback is that, due to the large amount of waste wood being removed in one cut, there can be quite a lot of break out of end grain on the shoulders.
- BANDSAW - This is my preferred method for the comparatively small tenons required in the making of a coffee table. The blade needs to be a combined rip and cross cut blade and of sufficient size to cut without deviation, minimum about 16mm but wider if possible. It is also important to ensure that the blade is sharp as a blunt blade will wander off line. Because of the length of time it takes to change and set up a new blade on a bandsaw, I keep my larger machine permanently set up for tenoning with a large blade and have a smaller bandsaw with a thinner blade for making curved cuts. The bandsaw can be set up, with the aid of a cross cutting jig and the use of stops, to make all the cuts for a haunched tenon.
Researched & written by Nick at TheCoffeeTable.co.uk - Copyright © TheCoffeeTable.co.uk - Telephone: 01420 474862