Checking a square is square?

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You professionals will like this.I have (or I did have) a small square that I've used for years. No idea where it came from, but it must have been hanging around for over 15 years and it was second hand when it showed up. I probably found it.The other day I was being extra careful with something I was cutting and it wasn't quite fitting together. Because I'd been careful with the setting out and the cutting, it occured to me that maybe the square was out. And it was! So I've been using a square for over 15 years that was a couple of degrees out of square. What a dill. I bought a big square last year to replace one I'd lost and it wasn't square either. It was a cheapie, so it serves me right.I know there is a way to check and see whether a square is true and I know somebody out there is itching to tell me what it is.Scott
Reply:The easiest way I can think if is draw a straight line(with a level or straight edge) Place the one leg of the square on that line and draw a line with the other leg(perpendicular to the first) then flip the square and check it the other way.   Or you can do it mathematically by your 3-4-5 rule,  3'  run 4' rise = 5' diagonal.  Take your normal framing square, its 24" run 16" rise =28 7/8" diag.or a smaller one 12" R x 16"Run = 20"diag.  Hope that helps"Lack of planning on your part does not constitute an emergency on mine"However "lack of planning on my part may constitute an emergency on yours"
Reply:I have a Starrett 12 inch and a smaller 6 inch combination square, both have the forged steel head.  I've had the 12 incher for over 30 years.  It is still very accurate.  They are expensive but will last a lifetime.Stumpster has a good method for checking the squareness.
Reply:they say to use a board an draw a line on top part of sq. then flip over an draw same line if different  it is off --some can be tapped with a hammer to correct an some --i guess need to be thrown a way--- dont rely on a square if buliding a big square project use a tape an measure corner to corner   ----  --X  it out
Reply:I've had more logs and stuff dropped on squares , levels, laser levels, chop boxes and such that I have gotten into a real good habit of checking them regularly.  Like my levels I have my lines(plumb and level) drawn on my wall so its quick and easy. I have points around my garage to check the laser and sight levels also. It shouldn't be necessary if they are taken care of but when I was a subcontractor other people do not treat your tools the way you would, and if I use a tool that's out of wack it comes out of my pocket. So I still do it even though I am the only one using them( a minute spent is an hour saved)  JM 2centscorner to corner ------X it out
Reply:Use the flip over method and then use a hammer to make it correct.  For all flat framing squares in any size  set it down flat on a heavy plate or anvil.  You strike one blow on the outside corner to close the angle then check.    To open the angle strike near the inside corner.  The idea is that you are stretching the metal to very slightly change the angle between the legs of the square.
Reply:I might retrieve that square from the bin and see if I can fix it.Now this will really crack you guys up....I bought my first proper boat (since sold) about 10 years ago. It was about 40 years old and timber. Around 28ft. Like all older timber boats it needed a bit of work done to it.The first weekend I had it I loaded up the car with my tools and headed down to where it was moored to do some work.I got onboard, took out my spirit level, and watched the bubble going backward and forward with the rocking of the boat.Just as well nobody was there to laugh at me.Scott
Reply:I threw all my sqaures away.  They kept changing from one time I'd check something to the next.
Reply:I got onboard, took out my spirit level, and watched the bubble going backward and forward with the rocking of the boat.
Reply:I think that might have been my sister.
Reply:Scott, ............. Now why do you think there is no such tool, as a level, in any tool box or why most workers don't know what one is, that work in a shipyard? Nothing against yardbirds, but ........................ .
Reply:Since most of us aren't building nuclear power plants, or space shuttles, the QUICK way I use to check squares is to stand them up and butt two of them up together, on something that has a known level surface, such as a piece of pipe or a piece of heavy angle iron. Butt the short edges together and then the long edges. If one is out, the way to check which one it is, is by using a third square.  Now, if you're talking about getting down to the nat's a**, well that's another story.
Reply:Reminds me of the time in my youth, a long time ago, when I wanted to do a very precise layout and borrowed my father's 30 cm. hand engraved stainless steel rule.  Couldn't get the thing to come out right so finally looked closely at the rule and found an 11 millimeter centimeter in the middle of the rule.  My father had been using it for years in his commercial artwork and never noticed the discrepancy.  Still works good as a straightedge.awright
Reply:Originally Posted by scott brunsdonI bought my first proper boat (since sold) about 10 years ago. It was about 40 years old and timber. Around 28ft. Like all older timber boats it needed a bit of work done to it.The first weekend I had it I loaded up the car with my tools and headed down to where it was moored to do some work.I got onboard, took out my spirit level, and watched the bubble going backward and forward with the rocking of the boat.Scott
Reply:Originally Posted by scott brunsdonYou professionals will like this.I have (or I did have) a small square that I've used for years. No idea where it came from, but it must have been hanging around for over 15 years and it was second hand when it showed up. I probably found it.The other day I was being extra careful with something I was cutting and it wasn't quite fitting together. Because I'd been careful with the setting out and the cutting, it occured to me that maybe the square was out. And it was! So I've been using a square for over 15 years that was a couple of degrees out of square. What a dill. I bought a big square last year to replace one I'd lost and it wasn't square either. It was a cheapie, so it serves me right.I know there is a way to check and see whether a square is true and I know somebody out there is itching to tell me what it is.Scott
Reply:Thanks Root Dog.Yes, Bob, I think owners of old boats tend to look back on them through rose coloured glasses.I had two of them. The first was the 40 year old one. The second was 38 feet long and built in the 1920s.I owned the latter for 5 years - till I had kids and ran out of time. I used to get it out of the water twice a year and when I put it back I would always spend the night on board listening to the pumps (I had 3 of them) switching on and off.It's hard to get used to the fact that every timber boat tends to have water in the bilge.I miss that boat, but I don't miss the expense it took to keep it floating and looking nice. My next boat will be an aluminium one on a trailer so I can still fish Sydney Harbour but not worry about it sinking.
Reply:Well, Root Dog, that 's interesting.  Here I've lived 69 years and never had that relationship in mind.  Very handy.  But not exact by an error that could   show up by one of the checks mentioned earlier.  Poeple should realize that it is a very close, but not exact approximation.  The angle defined by a 12 x 12 x 17 triangle is actually 0.2 degrees too large (0.198944078 degrees, for a closer approximation - don't you hate people with calculators?).  I don't have a sense whether this would be of any practical significance, since I usually make my errors by inches and feet, rather than hundredths of an inch or hundredths of a degree.awright
Reply:Originally Posted by stumpsterOr you can do it mathematically by your 3-4-5 rule,  3'  run 4' rise = 5' diagonal.  Take your normal framing square, its 24" run 16" rise =28 7/8" diag.or a smaller one 12" R x 16"Run = 20"diag.  Hope that helps
Reply:I prefer trapezoids, rhombuses (what ever the plural of rhumbus is, maybe rhumbi), and parallelograms myself.  That way I can claim that every thing I do is "custom fit".  Besides, I accidentally used my square for trim on a bbq pit.Smithboy...if it ain't broke, you ain't tryin'.
Reply:Originally Posted by scott brunsdonYou professionals will like this.I have (or I did have) a small square that I've used for years. No idea where it came from, but it must have been hanging around for over 15 years and it was second hand when it showed up. I probably found it.The other day I was being extra careful with something I was cutting and it wasn't quite fitting together. Because I'd been careful with the setting out and the cutting, it occured to me that maybe the square was out. And it was! So I've been using a square for over 15 years that was a couple of degrees out of square. What a dill. I bought a big square last year to replace one I'd lost and it wasn't square either. It was a cheapie, so it serves me right.I know there is a way to check and see whether a square is true and I know somebody out there is itching to tell me what it is.Scott