“Saddle” type jigs that fit over and slide along a table saw’s rip fence are handy for many purposes. Most of the designs I see look like the photo below, where spacer “B” is sandwiched between the “A” and “C” facings on either side of the fence. But, getting the sizing right for the sandwiched piece can be tough: too wide, and the saddle is too loose for an accurate jig.
If it’s too narrow, the jig binds on the fence. I prefer to make mine with the “B” piece overlapping “C” and butting against “A” instead. That way, I can slip a couple of playing cards next to the fence when I assemble the saddle to give it just the right amount of sliding clearance, and there’s no trial and error to get a spacer sized correctly.
– John Cusimano