Adjustable & Accurate Cut-off Jig by Don Firth, Toronto, Ontario donfirth@grampasworkshop.net

When you make a 90 degree cut, you want it as accurate as possible - right on 90 degrees. I feel in lots of home shops, 89.75 degrees or 90.5 degrees may be thought to be 90 degrees. Reading the commentary in Canadian Workshop Magazine on my adjustable cut-off jig, I learned something that I didn't know about making a fixed fence cut-off jig, and that is as follows: an error in the placement of the fence by as little as only 1/4 of a degree ruins the jig and all your right angle cuts with that jig.

That's not a problem with my jig, because it can be adjusted. The type of jig I needed was for relatively small pieces of wood - not for making cabinets, but any size should work out fine. Here's how mine was made.

The hardest thing to find would be inexpensive 1/4" thick hardwood strips, from which I could cut the runner that was needed on the bottom of the jig, which would then ride in the tables mitre slot. I was told by my new professional carpenter friends that they always have 1/4" oak strips left over, from kitchen installations they regularily do. During one of our early morning coffee sessions, they insisted that I take a few strips of 1/4" oak (no charge) to use for this jig and others which I might build.

Knowing some guys like these guys, can be really beneficial to a new woodworker. If you don't know any now, you've got to get to know some pros!

CUTTING OUT AND ASSEMBLING THE JIG: For the base, I used a scrap piece of 3/4" plywood approximately 14" wide by about 16" long (this is a personal choice). A 2" strip of the same 3/4" plywood was used as the fence. Cut this strip the same length as the plywood is wide. Place this strip on top of the base, at one end going side to side. With the end with strip towards you, drill a pilot hole for #6 screw in the middle of the left end. In the middle of the right end, drill a 1/4" hole through both pieces of plywood. Remove the 2" strip and at the 1/4" hole in its right end, make a slot 1/4" up and 1/4" down from the original hole with your router or other tools. This newly formed slot in your fence, will give your jig its adjusting feature. Set it aside when you have finished the slot.

Turn the base over, and with a 1" spade bit, remove enough material from the bottom side, that it will be able to accept a 1/4" nut & flat washer. Set aside.

Now, measure the width of your mitre gauge slot and cut your 1/4" oak strip to the same width. DO NOT CUT THE STRIP TOO NARROW. THE STRIP MUST MOVE FREELY, BUT FIT SNUGGLY BUT NOT TOO TIGHTLY IN THE SLOT, WITH NO "PLAY". Once the 1/4" hardwood is cut to the proper width, cut a piece about 2" longer than your base. Put the strip in the slot. Set the base on top in such a position, that when attached and pushed past the blade, the base would be cut end to end. Put lineup marks on the base and the 1/4" strip, turn over and using glue and 5/8" #6 or #8 counter sunk screws, attach 1/4" strip to bottom of the base, with a bit of an overhang on each end.

Run the base through the table saw and cut off the right edge.

From the bottom, insert a 1/4" flat head bolt through a 3/4" diameter washer and then through the base and fence, then another washer and finally a 1/4" wing nut. Making sure that the fence is at a right angle to the new cut, attach the strip with a 1 1/4" #6 counter sunk screw at the left end. By loosening and then tightening the wing nut, adjust the other end of the fence to a perfect 90 degrees by setting and cutting and checking the angle with a good square. Continue until you are "right on". The precise angle is set by the fence which pivots on the screw on the left end. The right end is able to move slightly, up & down, thereby changing the angle of the cut.

A hole was drilled in the base so that it may be hung up on a peg board.

If & when you notice the jig to be delivering inaccurate right angles, loosen the wing nut and redo the setup procedure. Here's to your always square crosscuts!

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