Sunday, June 27, 2010

Bar Stools- Mortise, Taper, Mortise

Next I mill up the front legs. This is the last point at which lefts and rights are interchangeable. I select for the best colour and grain to be exposed and put sapwood and defects to the inside. Not only are they less visible there, but the two inside planes of the legs get tapered, so there is a good chance flaws will be sawn off. The bottoms are marked with the chosen orientation.

I don't use the Leigh FMT often, but I really like it for oddball joinery- angled and compound mortise and tenons, or for tenoning parts like bent laminated skirts that don't register properly for the tablesaw.

The mortises are cut in the legs, in the locations that aren't tapered- the seat and back support rails.

Next I make a taper jig. I've used commercial and homemade versions of the commercial hinged jig, but I find them fussy to setup. I can make a custom jig in less time.

I start with a scrap piece of plywood, a little longer than my part.

I draw the taper on the stock, put the cut line on the edge of the plywood, and screw down a fence and a rear stop. If the fence or the stop overhangs the plywood edge, I send it back though the tablesaw to trim it flush.

The jig is then sent through the saw, which hasn't been changed since first cutting the plywood base. I am tapering both inside faces, it is important to do them in the correct order. First they are cut one mortise down, the other to the blade. Next, one mortise is up, the other to the blade. Doing it the other way around results in an already tapered face registering against the jig bed, throwing off the angle of the second face. The front legs are getting the same amount of taper on each side, but the leg itself is rectangular by 1/8" of an inch. A shim is used to compensate.

The saw pushes the part against the stop, I am comfortable leaving it loose on the jig, but if you like a hold down clamp like a De-Sta-Co can be screwed to the jig fence and used to hold everything secure.

The leg is rotated and tapered on the second face.

Next I taper the back legs. Using the same jig, I send the left legs through.

Because of the shape of the legs, the jig needs to be altered to cut the rights.

I would highly reccomend the use of hold downs for this process. I didn't, and the procedure was a little dicey. The leg need to be held down against the jig bed and the side fence, the jig needs to be held tight to the tablesaw fence, the whole thing needs to be slid past the blade while cutting forces are wanting to push the leg away from the end stop.

Now that the legs have been tapered, the mortises for the rungs can be cut, perpendicular to the face of the leg.


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I'm a woodworker on the Canadian prairie.