Somethings not lining up...

[billmayo]

This is the technique I use to test and square a framing square:

http://zo-d.com/stuff/how-do-i/how-to-c ... quare.html

[rdubbs]

For checking all sorts of angles, I believe in the Wixey angle gauge! It's great for table to blade on both the table saw and band saw. It will also nail the fence angle on the jointer, and set the table angle with the drill press. There are two ways, to my knowledge, to use it to set the angle on the miter gauge. All of my work has improved in angular accuracy since I started using a Wixey.

[8iowa]

Back in '06, when I attended one of Shopsmith's last traveling academies, the instructor challenged us to go home and check our squares. I did, and sure enough none of my squares were truly "square".

Since then I have invested in some accurate measuring tools and have re-alligned my shopsmith. This has resulted in significant improvement in my projects.

A set of engineer's squares, a high quality combination square, and an accurate straight edge is a good start. Shopsmith's dial indicator package has also been an invaluable tool in accurately setting the Shopsmith's table parallel to the blade.

Nick Engler has some good DVD's on alligning the Shopsmith. Even an old dog like me learned some new tricks.

[dusty]

On my saws I generally just flip the miter gauge upside down with the knob loose and shove it up against the front edge of the table and tighten the knob. You should check first that your table front is square to the miter gauge slot. You might find some odd ones that are not.
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You can also use the miter gauge slots to check your square.
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Far more errors are caused by careless marking than crooked squares. I have watched guys make a mark along a 2' span and change the slant of the pencil "substantially" from one end to the other and swear that they held it straight all of the way. "Somewhere" just recently I saw a picture of a device like a mouse that held your pencil at a constant angle to prevent that.
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It is also very easy to misread a measurement. That is why you should where possible avoid measurements and superimpose where ever you can. Marking with a Sloyd knife is also more accurate than a pencil.
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If all else fails specialize in "rustic" items.

I don't recall who it was that taught me to turn the miter gauge upside down in the miter track and press it up against the front rail on the main table. I used to check the miter gauge that way every time I put it on the Mark V.

Guess what, it still works. The table on the Belt Sander is equally convenient and equally accurate.

Now, having said that, I must admit that I use the MiterSet and the Wixey an awful lot to do just that - check for 90 degree settings.

When this post came in, I went to the shop, got one of the miter gauges, checked it with the MiterSet, checked it against the Wixey and then up against the front rail on the 520. There was no contradiction on any of them. The Wixey reported a 90.0 degree offset.

I guess this says that one way is just as good and reliable as the next.

Well, maybe not. The front rail has to be installed right or it won't be that accurate.

[charlese]

All of the above is good advice, however we missed an important part. First thing (which you probably did) is to make sure your factory edge is straight. Since milling the board may have taken on a new shape, or irregularly changed diameters. Wood boards are known to change shape and size.

The other thing worthy of mention is to always put the same edge where you butted the square, up against the miter gauge.

I also like this system to see if a crosscut is square: You first need a board where the two edges are parallel. Make one crosscut, flip one part of the board edge for edge, and slide the two freshly cut faces together. They should come together with no gaps.

It is a very good idea to make sure your miter slots are aligned with the blade, however such a mis-alignment will not result in an un-square crosscut.

After obtaining a MiterSet, I'm sold on that jig! With it setting any angle on your miter gauge is very simple and very accurate.

Nick showed us a very cool method to make sure you are crosscutting at the desired spot. http://www.shopsmithacademy.com/Tips_Ar ... gnment.htm This beats the dickens out of drawing a line. You only have to make one very small mark on the board.

[keakap]

Another saw-dust-less quick miter gauge square check: put a straight edged board that spans the table against the miter gauge, firmly; clamp (or hold) the board down, remove the miter gauge and re-place it in the other miter gauge slot, run it up to the board gently.
(Or, if you have two miter gauges (I still have my old 500 gauge), mount 'em both and the board should be perfectly flush with both faces. This, btw, makes a super quick crosscut "sled".)
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One way to insure that you never drop a good square-- buy one that has a life time warranty like Bridge City Tools. I bought my TS-2 20+ years ago and somehow it's never been dropped.
If it does get knocked out of true, ever, or run over by a freight train, it goes back to BCTW "for recalibration, repair or replacement, for $5".