Introduction: Universal Table Saw Jig
The Tablesaw Jig is a machinist's answer to making odd shapes and angles in really small or awkward pieces of wood on a tablesaw. The prototype I've built has been made out of anodized aluminum and stainless steel, but the enterprising craftsman will readily be able to make a similar adaptation out of wood or plastic according to their needs. I've omitted any drawings, as the measurements all depend on your specific application. Instead, I've taken the entire assembly apart in order to demonstrate how it all goes together, and why it works.
Step 1: Slider Blocks
Slider blocks are used frequently in manufacturing and production machinery, as it gives rigid support to the machine while still allowing for fine adjustment near a conveyor. I decided a scrap one laying around the shop, which had already been hard anodized, might make a great base for making miter cuts without a miter saw. Two 1" diameter slider shafts, along with a 3/4-6 ACME screw, are inserted through the slider block. The slider block has a pocket for a bronze nut which the screw acts on, and there is a hole drilled to the side of one of the bores for the shaft to provide for the brass clamp. There will also be two tapped holes for screws that attach the Jig to the pusher slide that is hopefully already on the tablesaw.
Step 2: Adjustment Knob and End Block
The adjustment knob was quickly turned on the lathe out of aluminum, knurled, and then bored in the center with a blind hole to accommodate the ACME screw. A set screw fastens the two together. It's important that you leave about 1/16" or so of tolerance between the end block and the boss of the knob, as the screw is only supposed to thrust against the bronze bushings, should you decide to have them.
Step 3: The Vice
The vice, which clamps down on your workpiece, is constructed very similarly to the slider block assembly for the main adjustment, only smaller since you don't need as much travel. The end block for the main adjustment is also the "dead" jaw of the vice, which the entire vice subassembly is attached to. In this instance, the sliders are smaller in diameter, but have also been bored through to accommodate long socket screws that reach down to the threaded holes in the dead jaw. The vice subassembly is held together by only two screws. The end cap at top is extra thick, as it is taking the force of the "live" jaw being forced down against the workpiece. A 1/8" thick steel plate makes up the very bottom of the vice, bringing the piece as close to the table as possible. This goes against the rule of thumb that you must have your piece flat against the table, but so long as the piece is tight and you feed slow, it works great.
Again, there is a bronze bushing which the ACME screw (this time a 1/2-10) is supposed to act against. (Try to make this out of Left-Hand thread, otherwise you'll have to remember to operate it backwards!)
Step 4: Final Assembly and Operation
Anodizing your aluminum parts like I did is only optional, but it sure looks awesome if you do. The whole assembly only takes a few minutes to put together, so long as the holes line up and you reamed the slider blocks .001" of an inch larger than the shafts that go through them. Mount the Jig to the pusher slide, and you're ready to go. Once you have set the angle you want and the thickness of the piece, using the Tablesaw Jig is just as easy if you already know how to use a tablesaw: Treat the blade like a loaded gun, and feed slow. Although your workpiece is 1/8" above the table, the rigidity of the tool keeps it from chattering during cutting.
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