Thin rip jig/ Pinch bar clamp

[Cherryville Chuck]

I wanted to try making a thin strip ripping jig which normally sits on the side of the blade away from the fence. I though that it would be good if I made it to fit either saw I have. A Unisaw with T slot and an old Rockwell with just a standard 3/8" x 3/4" groove. For that I needed to make a pinch bar to grip the regular groove. The pinch bar is simple, just a strip of wood with slots cut in the center from each end 2 -3 inches and a hole for a flat head machine screw and countersunk so that when tightened it would spread the ends of the bar out. Any time you slot wood like this you need to drill a hole in the end of the slot to keep it from splitting.

The pinch bar can be used for other applications such as feather boards or stops and that allows you to clamp in a miter groove on a router table or drill press besides being used on old table saws. When I tried it for the first time I was surprised at how tight it got.

I made the ripping jig both Imperial and metric by threading in carriage bolts on either side, one being 3/8" by 16 thread and the other side was a 10mm by 1 mm thread. The carriage bolts have smooth rounded heads so wood slides easily on them. Any time a bolt is used for adjustment I prefer to use one or the other as those make it easy to estimate adjustment. With the 3/8" bolt one full turn moves the end 1/16 inch fairly precisely so 1/4 and 1/2 turns are 1/64 and 1/32 respectively. With the metric bolt one full turn is a one millimeter movement. One quarter turn on a 1mm bolt would be about 1/100th inch.

If you want to make one for a T slot type groove then just take a couple of flat washers that fit the groove and countersink the holes so that the same bolts fit flush to the bottom of the washer.