Construction, Part II:
Jig Making, Shaping the Legs, More Joinery
Shaped legs like these can be formed by making an L-shaped cradle jig, as in the photo and sketch below. The squared leg blank is attached to the jig and shaped on the spindle moulder (US shaper) or router fitted with a pattern cutting bit.
To make a suitable jig, cut two pieces 18 mm ply or MDF to 1180 mm long, the same length as the leg, and 72 mm± wide (Piece A above) and the other 90 mm± wide (Piece B above) Dry biscuit the edge of Piece A to the face of Piece B. Mark a line along the inside of the corner on piece B. Plot the outside profile required on Piece A. (Ignore the inside curve at the bottom of the leg.) The profile can be plotted directly onto the MDF, or a full size paper template attached. Cut and smooth the curves.
Attach this shaped piece A to B as shown at right with countersunk (US flathead) screws. Cut close to the profile on A with a bandsaw and finish Piece B with a router and top mounted bearing pattern cutting bit. The tiny rebate on Piece A at the inside corner can be formed next, and provides a space for dust.
Glue and screw the jig together with the biscuits and countersunk screws. Ensure that the faces are perpendicular to one another. Trim the outside corner flush when dry.
Drill offset countersunk screw holes in each face of the jig into what will be the surplus at the top of the leg. Repeat at the bottom end. Place the inside corner of each leg in the jig and screw them in. Trace round the jig to mark the leg.
Now that the exact profile of the leg is known, the bottom front rail that attaches to the cabinet bottom (dry biscuited four paragraphs previously) can be cut to length remembering that the distance between the shoulders is the length of the cabinet bottom, plus 24 mm, (i.e., 12 mm MDF X 2 as used to cut the biscuit slots in the leg.)
Mark and cut mortises and tenons in the square leg blank. Set the back face of the rail flush with the back face of the leg, and the front face inset from the front of the leg. Leaving this job until now lets you make any minor adjustments to the rail thickness and to establish a safe mortice depth that doesn't penetrate through the outside face of the leg.
Bandsaw the waste from the legs. Cut one face, and re-attach the offcuts with masking tape. Cut the second face. Screw each leg back into the jig and use the spindle moulder, or a router and pattern cutting bit to follow the profile. Extra screws may be inserted to secure the leg in the jig, but screw only into the biscuited face; the holes will be hidden later. (These legs are from a different job, but the profile and procedure is the same.)
Complete the legs by cutting the short curved inside faces at the bottom; a small card template can be made to trace around, then bandsawn, and planed. Clean up all the machine marks and do any rounding over with hand tools in preparation for gluing the legs to the side panels.
The chord of a circle can be marked at the bottom of the two side panels and the underside of the front rail. Cut and smooth these. A pattern of MDF for use with a router and pattern cutting bit speeds the job up. Glue the legs and panels together with biscuits, using a rig made of the curved leg offcuts for the sash cramps.
When the glue has cured cut the sides to length on a panel saw. Use the reveal at the leg to panel junction as the datum point for the saw fence, shimming, and packing as necessary to hold it flat and square.
Bevel the underside of the feet with a hand plane to strengthen short grain and reduce the chance of flaking off.
© Richard Jones, 2001. No part of this article
--text, photographs, slides, sketches, working drawings, etc.--
may be reproduced in any form
without the express written consent of the author.
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