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A fence is used on a table saw to make cuts exactly parallel to an edge of the material being cut. When we want to make a cut that is not parallel with an edge, one way to do it is with a jig. We could make a simple jig with the exact angle we need for this project or make a little more complex one that can be adjusted for whatever angle you might need in the future as well. We'll call it a "tapering jig".
The tapering jig consists basically of two pieces of wood that can be adjusted to different angles. The jig is placed against the fence, the material to be tapered is placed against the jig and both the material and the jig are moved along the fence together giving a straight cut at an exact angle.
Let's start making this jig by ripping two pieces of 3/4" plywood 2 1/2" wide (about the same height as the fence) and cut to 30" long. Find a piece of piano hinge or butt hinge about 2" to 2 1/2" long and fasten this to the two pieces of plywood so when they are placed with their 2 1/2" faces together are even in length. After installing the hinge on one end, they will open up on the opposite end. Keep the hinge flush or below the top and bottom edges of the plywood pieces.
Now we must devise a way to keep the jig from opening too much or not enough and stop at the precise point we want. To do this we need a lock or stop of some kind. The easiest adjustable lock to make is one from 1/4" plywood.
Rip a piece of 1/4" plywood 1" wide by 6" long and round the ends nicely. At one end drill a 3/16" hole, centered on the piece and 3/8" from the rounded end. Measure 1" from this same end and drill a 5/16" hole. At the other end of this piece, come in 1/2" and drill another 5/16" hole.
Now connect the sides of these two 5/16" holes with a pencil line so that you have two parallel lines 5/16" apart and ending in a 5/16" hole at each end. Cut these two lines very carefully with a jig saw using a fine blade. Be careful not to push the blade too hard and break the plywood.
Cut from one hole to the other along the two pencil lines to form a slot. This slot should be able to have a 1/4" bolt slide along it without catching up anywhere.
Assemble the slotted lock onto the top edge of the jig. Screw the 3/16" hole end to the right hand piece so the rounded end is flush with the outside face of the jig and the screw is placed about 2" from the end opposite the hinge. Use a #8 x1 1/2" screw with a 3/16" flat washer over and under the slot.
Pre-drill the jig to accept the screw and tighten so it's just snug. The lock must be free to swivel on this screw. On the other side of the jig, about 2" from the end opposite the hinge, pre-drill a hole and install a 1/4" diameter leg screw. Assemble the slotted lock with a 1/4" washer above and below the slot onto this leg screw with a 1/4" wing nut. (A leg screw is a fastener with wood screw threads on one end and machine threads on the other. It is used primarily in attaching bed or table legs to a metal plate fastened to the frame.)
Next we need to install a stop for the material we are tapering so it can be moved with the jig as one unit. This is done by attaching a piece of 3/4" plywood with measurements of 2 1/2" x 1 1/2" onto the left hand side of the jig at the end. Pre-drill two holes for #8x1 1/2" screws and glue and screw the small piece on. Keep the top and bottom flush with the jig and overlap it by 3/4" on the outside, forming a stop for the material to rest against.
Okay, we've created a jig, but how do we use it? From the sketch you can see that our jig is on the table saw against the fence.
Place the jig on the table saw with a leg or board to be tapered. On the leg or board draw a line where the taper will be—1" at the bottom end and 1 1/2" at the top end. Orient the leg as in the sketch with the bottom of the leg against the end stop. Move the fence about a foot away from the blade and lock it in position. Now adjust the jig so when the leg or board is against the jig and the jig is against the fence the line on the leg or board is parallel to the saw blade. Slide the jig and leg or board back and forth along the fence to get these measurements. When sliding the jig, make sure the jig and leg or board move as one unit without any slipping between them.
Adjust the fence and jig towards the blade until the blade just starts to cut the line at the start of the taper near the top.
Works pretty good, eh?
When out in the field and the tapering jig is at home hanging up nicely in the shop, another trick to tapering a board is as follows. Mark the start and finish of the taper on the board. Use a board of equal or greater width and length to nail on top of the tapered board to use as a guide against the fence, as shown in the drawing .
