Accuracy of a Square

[George Bokros]

I have a framing square that I just checked for accuracy. It is off ~1/64 over 23 1/2", should I accept that as accurate? I did the draw a lineflip and draw a second line test and there is 1/32 between the two lines.

Thanks

[Art Mann]

That may be the best you can do with a framing square, although there is a technique to adjust the angle a little if you want to fool with it. Framing squares are used for framing houses and that amount of accuracy far exceeds any house building requirements. To get really good accuracy, you are going to have to pay more and you needn't even look at a big box store. I have taken two identical framing squares off the rack and put them up next to each other and found 1/8" or so difference over the whole length.

[George Bokros]

That may be the best you can do with a framing square, although there is a technique to adjust the angle a little if you want to fool with it. Framing squares are used for framing houses and that amount of accuracy far exceeds any house building requirements. To get really good accuracy, you are going to have to pay more and you needn't even look at a big box store. I have taken two identical framing squares off the rack and put them up next to each other and found 1/8" or so difference over the whole length.

Where do you suggest to get a more accurate square the size of a framing square.? I want to use it to set up the track saw for cross cuts of sheet goods.

[scott vroom]

A bit pricey.....but they claim to be .001 accurate at the angle. http://www.leevalley.com/US/Wood/pag...936,42944&ap=1

[George Bokros]

A bit pricey.....but they claim to be .001 accurate at the angle. http://www.leevalley.com/US/Wood/pag...936,42944&ap=1

They claim .001 radian or 1/32 doing the standard square test and my framing square is least that accurate. My question is, is that accurate enough for woodworking?

[Garth Almgren]

In the instructions, they say that translates to 1/32" over the length of either leg.

[lowell holmes]

Well, if you center-punch the square at the outside or inside corner, you can move the tongue in or out. This should correct the square. I can't believe these old woodworkers didn't come up with that.
The center punch should be placed really close to the corner you decided to adjust. Watch this- https://www.youtube.com/watch?v=azMBpXqDJW0

[Phil Thien]

They claim .001 radian or 1/32 doing the standard square test and my framing square is least that accurate. My question is, is that accurate enough for woodworking?

Right, yours is a little more accurate.

Hopefully obviously, the edge on which you reference your square needs to be perfectly straight. Any deviation from straight on that edge will translate to measurement errors.

Also, I've found drawing two knife lines to be a bit more accurate than two pencil lines.

But to answer your question, 1/64" over 24" is perfectly acceptable for most anything you'd do in woodworking. I'm trying to think of something where that wouldn't be accurate enough but nothing comes to mind.

[scott vroom]

In the instructions, they say that translates to 1/32" over the length of either leg.

Mmmm....if the 16" leg is off 1/32 then wouldn't the 24" leg be off by an amount greater than 1/32? So how can they claim "1/32 over either leg"? Or am I just geometrically challenged?

[jack forsberg]

Well, if you center-punch the square at the outside or inside corner, you can move the tongue in or out. This should correct the square. I can't believe these old woodworkers didn't come up with that.
The center punch should be placed really close to the corner you decided to adjust. Watch this- https://www.youtube.com/watch?v=azMBpXqDJW0

while i agree with the punch the video show it being done in the wrong place IMHO. It should be in a line that is a miter. And a cold chisel is way faster as a spreader.

[George Bokros]

Made a mistake in original test. I am off 1/32 not 1/64.

Guess I am as accurate as the Lee Valley square.

[Al Launier]

I agree & wondered myself, but decided to cut them some slack as I felt they may be suffering from a Senior Moment as I frequently do.

Well, if you center-punch the square at the outside or inside corner, you can move the tongue in or out. This should correct the square. I can't believe these old woodworkers didn't come up with that.
The center punch should be placed really close to the corner you decided to adjust. Watch this- https://www.youtube.com/watch?v=azMBpXqDJW0

[Rich Riddle]

Made a mistake in original test. I am off 1/32 not 1/64.

Guess I am as accurate as the Lee Valley square.

And you're $68 to the good (plush shipping). I have a Empire square as accurate as the Lee Valley model. Short of purchasing an engineering model, which would prove very expensive, you are likely as good as it gets with what you have.

[Greg R Bradley]

1/32" off is 0.031" off over 24" or 0.015" off over 12".

I use a Woodpeckers 26"/16" square to set my MFT. They claim theirs' is accurate to 0.001" per foot. I've found the Woodpeckers to be more accurate than required as there is more than that amount of flex in the track and the mechanism that keeps the saw on the track. Using one that is accurate to 0.005" over 24" that also has a short leg at least 12" long seems fine with what I've done.

You are 15 times the maximum error on the Woodpeckers unit. Somewhere in between is probably "good enough" in that you don't really need the accuracy of the WP unit but yours' seems "not good enough". I guess it depends on what you are building.

Another factor is that a thin square like the one you are using works poorly for setting up a MFT.

Another note based upon my experience: The legs being long are a huge help in setting up a MFT accurately. In other words a super precision square that is only 12"/8" isn't much good. Woodpeckers current MFT Square probably is optimum for use as much for the 1" thick outside edges as the 17"/17" leg dimensions. Way too single purpose and too expensive to be justified for me.

[Robert LaPlaca]

Might want to check out Chappell framing squares, just remember accuracy costs.. http://chappellsquare.com/product/framing-squares/