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How square is square enough?

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Forum topic by TopamaxSurvivor posted 1682 days ago 3455 views 0 times favorited 104 replies Add to Favorites Watch
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TopamaxSurvivor

14589 posts in 2274 days


1682 days ago

Topic tags/keywords: square squares tolerance

Occasionally, there has been discussion of squares being truly square on LJ. Lately, I have checked a few. My own framing square has been checked several times and my combination squares against it. They all show square. Tonight, for curiosity, I checked the framing square using 3,4, 5 right triangle measurements. It measures dead on. I double checked it with my Wixey, again, dead on. I have randomly checked framing squares in the big box with a 3,4, 5 measurement. I have yet to find one that is off. I’m getting curious as to why everyone else has out of square squares?? What are you doing that these methods aren’t good enough?

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence


104 replies so far

View BlankMan's profile

BlankMan

1487 posts in 1951 days


#1 posted 1682 days ago

How are you doing the 3, 4, 5 measurement? Relying on the 3, 4 stamped on the square? :)

But you gave me a good idea, I’ll check mine with my Wixey and see, I’ve always used my Starrett square before. Lord help if that’s off! ;)

-- -Curt, Milwaukee, WI

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TopamaxSurvivor

14589 posts in 2274 days


#2 posted 1682 days ago

Actually, I’m multiplying by 4; therefore, using 12 & 16 on the scales and measuring the diagonal with my tape.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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BlankMan

1487 posts in 1951 days


#3 posted 1682 days ago

I just measured a really old 24” square I have, it’s 0.2 degree off inside and out.

A newer 12” is 0.1 degree off on the outside, ok on the inside.

A newer 24” is 0.1 degree off on the inside and dead on the outside.

But even at 12×16 0.1 degree is only 0.020” off at 12”, is your tape that accurate?

These things are stamped out on a punch press, are punch presses all that accurate? Maybe they’re ok for framing a house?

Maybe they don’t really care about square, they just put the markings in the right place so the 3, 4, 5 rule works. LOL

-- -Curt, Milwaukee, WI

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lilredweldingrod

2495 posts in 1705 days


#4 posted 1682 days ago

I usually tape a piece of paper to my saw top, align the short end of the square to the table edge and make a line on the paper. Flip the square 180 degrees and check the alignment with the mark I just made. Can not fail.

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TopamaxSurvivor

14589 posts in 2274 days


#5 posted 1682 days ago

it’s just a standard ol’ Stanley. Considering wood movement, what would one need to square that a tolerance of +/- o.1 degree would matter?

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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BlankMan

1487 posts in 1951 days


#6 posted 1682 days ago

Let’s say your making a cabinet, you cut the boards to 18” width, you then crosscut them and you’re off by 0.1 degree, that’s a 1/32” at 18”. You measure the length at each edge and it’s the same and what you want, but it’s a trapezoid not a rectangle. And if all four boards are this way you put it together aligning the edges and it’s not square. Hmmm. What happened?

My machines are dialed in to 0.001-0.002”, time consuming to do but when I make something that is a square or rectangular I don’t have to put a clamp across two corners to pull it square and hold it there while the glue is drying.

-- -Curt, Milwaukee, WI

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TopamaxSurvivor

14589 posts in 2274 days


#7 posted 1682 days ago

I suppose a hobbist would do that, but I doubt if the production shops would care. :-)

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View mtkate's profile

mtkate

2049 posts in 1923 days


#8 posted 1682 days ago

I still remember my teacher going on and on about square squares. He said the root cause was buying cheap ones. Of course, repeatedly dropping a good one doesn’t help either….

View stefang's profile

stefang

12572 posts in 1932 days


#9 posted 1682 days ago

Well Bob, I tend to agree with you. We don’t really need to obsess over absolutes, but some folks have to in order to be satisfied. I say more power to them. Myself, I’m satisfied with staying on the wrong side of perfect if for no other reason than to save my sanity. We guess we need both types of people to maintain balance in the world. Yin and Yang?

-- Mike, an American living in Norway.

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Moron

4666 posts in 2491 days


#10 posted 1682 days ago

easy method to check

put the framing square against a crisp edge of a piece of plywood and draw a pencil line, then flip the square and check if the pencil line is perfectly parallel. Do it with both the 16” edge and the 24” edge.

-- "Good artists borrow, great artists steal”…..Picasso

View rhett's profile

rhett

696 posts in 2265 days


#11 posted 1682 days ago

I used to work for a trim carpenter, when I would make comments about something being in or out of square his reply was always “square is a theory”.

-- http://planeandsimpleblog.wordpress.com/

View marcb's profile

marcb

762 posts in 2271 days


#12 posted 1682 days ago

I don’t remember my trig well enough to tell you how much .1 degree is going to affect you on case work, but every time a production shop handles something twice to clean up an edge they lose money. If they don’t care, then thats bad business.

It’s easy enough to make sure things are correct up front and not have to worry about it.

Wood movement isn’t an excuse for sloppy work. Wood moves in known and predictable ways that should be incorporated into a design.

View CharlieM1958's profile

CharlieM1958

15661 posts in 2816 days


#13 posted 1682 days ago

It’s funny how we all seem to fall into one of two camps. One group says “close is close enough” and the other group strives for perfection.

It reminds me of how my dad (a civil engineer) explained to me many years ago the difference between a mathematician and an engineer.

He said, “Let’s suppose a nude woman is standing on the other side of the room 20 feet away, and you are allowed to approach her incrementally by closing half the distance at a time. The first time you move 10 feet closer, then 5 feet closer, then 2.5 feet closer, and so on. Now, from the mathematician’s point of view, you will never reach her, but, from an engineering standpoint, you can get close enough.”

Close enough for what exactly I was never quite sure. :-)

-- Charlie M. "Woodworking - patience = firewood"

View Walnut_Weasel's profile

Walnut_Weasel

360 posts in 1820 days


#14 posted 1681 days ago

I test for square in the same method mentioned above of drawing a line, flipping the square 180 and checking it again. You can also test levels this same way. Shim one end to until it is level, then flip it 180 degrees. I have bought several box store squares AND a “value” square from Woodcraft that are, in my opinion, very unsquare. I did not measure the exact amount out, but we are talking more than 1/32” over 6”.

Something else to consider – the amount of acceptable error is also impacted by the scale of the project. If you are out of square 1/32” on a joint for a 6” jewlery box it looks much worse than being out 1/32” on a full size computer desk simply because of how your eyese focus on the two different objects.

-- James - www.walnutweasel.wordpress.com

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PurpLev

8476 posts in 2246 days


#15 posted 1681 days ago

Charlie – that was priceless!

fact that wood moves has nothing to do with squareness.

the fact that wood moves should be accounted for equal measurements across the entire project (parallel parts or equal length that will move together) but a square joint/corner, needs to be square!

of course we cannot have perfect 0.000” error margin, but we should strive to get as close to it as possible especially with case work. where unsquareness WILL throw the entire project off. then you need to start redoing each and every piece to match the error instead of having everything precut and ready to go.

but as mentioned – beauty is in the eye of the beholder. and so is squareness (look at Picasso). woodwork is a visual art – as long as it looks good , it’s square enough for me ;) (ok , maybe not to me… but for some)

-- ㊍ When in doubt - There is no doubt - Go the safer route.

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