Popular Woodworking 2000-02 № 113, страница 13
perimeter cuts Jig for Perimeter Cuts Perimeter shaping is done with the flat jig.The workpiece is secured on a pivot and supported by the V-block.The procedure is standard;repeat passes with the blade raised a bit after each one. Here the jig is clamped in place, and the position of the pivot-point and V-block are established. Because the blade is exposed, be sure to use the saw's guard. adequate support for the work. Size the U to provide a tight fit for the bar. Now separate the pieces and form the rabbet cut along the base of each of them. Attach the parts to the platform with glue and 3/4" brads that are driven up through the platform. Be sure the vertical pieces are centered on the platform. Cut the bar to size and drill a 1/2" hole in its center. Install the insert and place the bar with glue, being sure the insert is exactly over the kerf in the platform. Make the pivot as suggested in the drawing or use a readymade 6" eyebolt. In Use Clamp the jig so the pivot is centered over the saw blade. Workpieces are prepared with a slight, exactly centered countersink for the pivot-point to rest in. Thread the pivot down until it sits in the countersink, tight enough to hold the work firmly but allowing it to be rotated. Then tighten up the lock nut to secure the setting. Work of any size—round or square—can be established with the jig. Variations are possible so long as you remember there is a critical relationship between the size of the work and the diameter of the blade. Perimeter Cuts Outside cuts, like the one shown in the photos above, are feasible on round projects, but the procedure calls for the jig shown in the drawing titled "Jig for Perimeter Cuts." Make the jig by following the steps suggested for the overhead jig. Start with the platform and center it over the saw blade by using the rip fence, then add the guide bars. The V-block is an optional but wise addition because it can supply security when doing the work. Also, the V-block can add to the jig's function. For example, use it to make miter cuts on frame components that have been pre-cut to length. Like inside cuts, perimeter shapes are produced by making repeat passes with the saw blade raised a bit after each one. The shape you get is affected by the size of the saw blade, where the jig is clamped and the placement of the pivot point. Approach this area of pivot work carefully because the saw blade is exposed, so be sure to use the saw guard! Even with the guard in place, don't use the technique on projects smaller than 6" in diameter. pw R.J. DeCristoforo is one of Popular Woodworking's contributing editors and the author of dozens of boohs about woodworking. His most recent book "The Ultimate Woodshop Jig Book" is available from Popular Woodworking Books. |
