Quality of a Square?

[Bluetobb]

I am a beginner wood worker. I was told one of the essential tools beyond any power tools is a good machinest square. So... I went to my local Woodcrafters and purchased a $60 Starrett Machinest 6" square. I was happy with my purchase and excited to use it to better set up my TS. When I started using it to check alignment of the fence with the miter slot I found what I think is a flaw but it might be so small that it is to be expected and/or does not matter for what I am doing.

When I placed the steel ruler of the machinest square in the slot width wise. As if I was ripping the ruler on the TS but had it stood up on end. One end of the ruler fit in the slot perfectly and I could not twist the ruler at all, it was locked in, the only thing I could do was pull it up out of the slot. But when I put the other end of the ruler in the miter slot at the same spot the fit was loose. I could spin the ruler in the slot. I hope I explained this well if not I will try again.

Is this a reasonable amount of imperfection in a $60 machinest square? I am guessing it is only difference of less than 1/32 of an inch but I am not sure. Any advice would be much apprecaited.

Thanks Dan

[Kevin P. Fleming]

A machinist square usually has a large heavy "body" and a thin "blade". With that type of square, you wouldn't be able to put both ends of the blade into the miter slot, because one end is embedded in the body.

Exactly what type of square do you have? Can you post a URL to a picture on the web from the dealer or manufacturer's web site?

[JackD]

You are saying that one end of the ruler is wider than the other? While theoretically, the blade (ruler) could still be square with the body on one side, the other edge of the blade would not be square. That would be a problem if you were using the non-square side of the blade to check something. I'd take it back and have them measure it with a caliper to confirm your observation. Then have them check through the rest of their stock to find one which doesn't have this problem. A 32'nd in one foot is enough to make things not fit right.

-Jack

[CW]

[Bluetobb]

I have misspoken, I told you I was a beginner. I am now looking at the box and it is a Starett combination square the numbers if they mean anything are C11H-6-4R. I have a Delta 36-650 contractor saw. It is the low end of the Delta contractor saws.

From what I have read here, it sounds like it is more likely the saw, but I should have my combination tested at the store. The miter slot being out of wack does not make sense to me because I tested the end of the ruler at the same place in the miter slot. So, it would be the ruler that would be different not the slot. Unless the slot is really wacked, which is possible.

Thanks for all the comments, please keep them coming!!

Dan

[Unisaw A100]

So in other words, you had the square set up so it was being used as a depth gage so to speak? When you retracted it from the slot it read 3/8"?

Sounds to me like your blade is wider from one end to the next. If this is the case then it's not right. A quick trip back to Woodcraft to check it against another square or in this case using a caliper is in order.

On the other hand, you've got a pretty rare tool there. I've never heard of a Starrett that was out of the box out of whack. Kinda like a stamp or money that comes from the mint with an imperfection.

Oh by the way, the blade on these squares should be dead nuts 3/4" wide. Your miter slots are seldom dead nuts 3/4" wide and usually you'd be able to set the blade into the slot anywhere up and down the length without it becoming stuck. I doubt it's the saw table.

UA100

[Swingman]

The blade of your combination square should be the same dimension from one end to the other. If it is not, then you need to take it back.

[Keith Carlson]

How accurate should I expect a combination square to be? I got a cheap one from Enco about a week ago (thinking it might not be great for machinist work, but good enough for woodworking). Took it out of the box and checked it with a precision ground square. Holding it up with a light background, I could see a gap. (Comparing two of the precisions squares showed no hint of any gap). Should have measured it with a feeler gauge, but anyway, the cheap one is going back.

I have an old Stanley that was my dad's, but that's square either. (Actually, the old Stanley is what got me thinking "if I'm using a square to check if a workpiece is square, and the square's not square....hmm...I need a solid reference square - hence the precision ground set).

Now I'm wondering what combo square I should look for, and what kind of accuracy can I expect? With a reasonable cost, of course, which for me is < $50.

[David Binkowski]

I just thought of one good way to determine if a square is square... On a flat surface, with something clamped to it at 90 degrees, hold the square against the flat surface and the clamped item. Draw a very fine line using the edge of the square. Then turn it around 180 degrees and draw another line right over the first. If there is any deviation from square, the lines will diverge. It should be readily apparent since the amount of the error is doubled. If both lines are exactly parallel, the square must be good.

[CW]

It could be those repressed memories of that technique being discussed here many, many times have just reemerged.

[Unisaw A100]

For wooddorking, you should be able to place it up against a freshly jointed board, mark a sharp thin line, flip the square and not see any deviation.

To name a few, Starrett, Brown & Sharp, Lufkin, Union and that Mititoyo (Japanese company whose name I always forget how to spell). You can usually find one or all the above on eBay in your price range. One of the nice things about a Starrett is they (Starrett) will take your old squares and bring them back up to snuff for a small fee. It would be real nice if it was for free but...

Anyway, on eBay, go slow at first, test the waters and when you feel a wee bit of confidence jump in.

UA100

[Groggy]

Dean seems to have stumbled across an old epiphany.

Greg

[Doug Miller]

If it's *that* far off, it's defective. Just take it back to where you bought it for exchange or refund. Don't waste time trying to fix it.

-- Regards, Doug Miller (alphageek-at-milmac-dot-com)