re: Miter Sled help?

I just went with a good square. That’s my 4th square. All the previous 3 where not square along all their length. There were good for 1 to 2" maximum.
The square must be square. A lot of squares are square to 0.001 for the first few inches and the rest of it has a higher tolerance.
Make sure your fence is not glued so you can adjust it until you get it square.
Cross cutting small pieces will not show the errors much but wider crosscut will show it.
The 5 cut method mentioned above is great.