Table Saw Set-up Tool
I designed this for setting up my table saw. It rides [tightly] in the miter slot, so it can be used to both set the blade and the fence.
The thumb screw allows you to run the standard ruler up against a tooth on the blade or the fence, and lock the ruler in a position.
This allows you to spin the blade back, so the tooth you set up off of is now at the back of the saw throat, slide the gauge back to the tooth again, and check for gap or tightness.
If you found a gap at the front or back blade position, you would adjust your table top to be square to the blade.
You can do the same thing with the table saw fence to determine its accuracy.
I found the gauge far quicker and accurate than a tape, when using older, less accurate fences.
This is, somewhat, like a T-square, so can be used for other purposes too, which can be handy if you are using a longer ruler.
The entire gauge is aluminum.
The part riding in the miter track has two parts that are the same. The thickness must be the same as the dept of the miter slot (3/8" on my cabinet saw) and just a hair narrower than the track.
These dimensions allow the ruler to lay flat on (ride on) the table. Tight tolerances minimize slop and give good set-up results.
The top piece could be any thickness, but, by making it the same as the part riding in the track, the gauge could be flipped and used with the ruler going the other direction.
The two polished portions are the spacer for the ruler and stop it from moving off to an angle. They are just a smidgen thicker than the ruler used.
I use an eighteen inch machinist ruler, but a twelve inch will do just fine for most set ups. Of course, the longer the ruler, the wider the cuts you set up for using the gauge.
Several decades ago, before I had a good fence, a friend would come over and use my saw. He worked cabinet shops and insisted on using a tape to set up cuts, as he'd done in the shops and was commonly to the day.
Using the fact it was my shop, I blackmailed him into trying my gauge. Grudgingly, did, but went back to a tape. However, after only a few set ups, he tried the gauge again, admitted it was easier and more accurate, and never went back to a tape.
The reason I have what you want is, I never lent it out before.
Scraps are a myth.