I’m making a new table saw sled and I wanted a large square to make sure the fence was 90 degrees to the cutting edge. But I wanted it to be dead accurate. For a good quality, accurate one, it costs a ton of money. Now it won’t be as durable as steel or aluminum, but it will work for this purpose. I had some 1/4” acrylic, so I laid it out in vectric aspire, exported in .svg, loaded it into the GF, and 20 minutes later it was cut out. I was going to use the Weld-on I have, but couldn’t find it (I will just before I die). So I took some bondic UV adhesive and tac welded the pieces together and Voila! One 18 by 9 inch square. And here it is.
It has a 1/4” haunch on both side of the short leg. Now I just have to find my feeler gauges to see how accurate it is.
That should work splendidly. I am currently working on something similar.
Most glowforges are out of square by a tiny bit. You can tell if you ever go for a perfect kerf corrected circular inlay or inset box lid. As you spin it you will feel it get alternately tighter and looser every 180 degrees. You’re essentially making very slightly rhombic circles if such a thing exists.
I’ll be curious to see what your feeler gauges say.
I too would question the perpendicularity of the GF, and it may actually be measureable at the length of your square. Before you make your sled, place this square on it with the short leg facing left, and strike a line. Now flip the square over and strike another line, very close to the first. How parallel these lines are is a measure of the squareness of your square.
Anyway, you may only be using this square to initially set the fence of your sled, and could fine tune it with the 4/5 cut method.
Nice practical cut. Let us know how it checks out when you check it.