Checking a square!

[dobbslc]

I found a problem tonight as I was about to square up my mitre saw.
I have an RDG tools type DIN 3" square an old 6" Moore & Wright one a digital one and a Picador combination square and almost all of them read differently!
The Picador turned out to be bent so is in the bin!
The Moore & Wright and DIN ones are very close but the digital one is a few degrees out!
How do I check which ones are good or bad?

 

[steve_s]

measure it 3 4 5
like this https://taleghan.us/more/how-to-square-joists-deck

 

[Brad93]

I keep a 12” reference square.

But one kinda down and dirty method is get a sheet of steel with a sheared nice straight edge. Put the square on it and scribe down both sides.

Flip the square over.

Do the scribe lines meet the edge of the square?

 

[Paul.]

Scribe a line using the square working off the straight edge of a piece of sheet, then flip the square over and see if the square lines up with the scribed line.

 

[Hood]

Get a surface with a true edge, place the square on and draw/scribe a line, flip the square 180 degrees and see if the mark lines up.

Edit, beaten to it

 

[Stingray]

Get a piece of plate with very straight edge, put your square on the edge, get a piece of flat bar (preferably engineers flat bar, not ordinary) lay the flat bar on plate and offer flat bar up to leg of square, clamp the flat bar securely, check again to make sure no gaps and everything is touching, carefully remove the square, turn square other way and check against other side of flat bar, if you can see no gaps and nothing has moved (flat bar) then your square is square, you can do the 3,4,5 thing but not easy to measure small items, you can also check them on the corner of a sheet of steel but you must check the sheet is square (measure lengths,widths and diagonals are the same, and sit the square on the corner.

Edit beaten to it as well

 

[eLuSiVeMiTe]

As above. First test I do when I buy a roofing square. Then fine adjust with a center punch and hammer. There never quite right.
Not sure how you would adjust anything else though.

 

[Stingray]

Bought a brand new sheet framing Square from screwfix, got it home and checked it, it was 3mm out on the 24" leg...

 

[8ob]

Just check them against a hypotenuse cal. https://www.miniwebtool.com/hypotenuse-calculator/

Bob

 

[eLuSiVeMiTe]

Bought a brand new sheet framing Square from screwfix, got it home and checked it, it was 3mm out on the 24" leg...

Scroll down to fine tuning a framing square.
Should be fixable. Cba to type myseld lol

https://www.fix.com/blog/hip-to-be-square/

 

[eLuSiVeMiTe]

These are brilliant with a framing/roofing square.
https://m.ebay.co.uk/itm/Johnson-Br...UO9ma&_nkw=stair+gauge+clamps&_from=R40&rt=nc

 

[R-D-R]

Google the 5 cut method for checking your saw. I was gutted when I lined up my so called engineers square on my latest Mitre saw to find it was out. I was close to starting to mess with the saw which was supposed to be super accurate but then the 5 cut method recommend on a forum showed the saw was bob on and my square was at fault!

 

[Welderpaul]

Use a mill and set the stock on the bed. Use the quill with a clock and run up and down the blade.

 

[doubleboost]

4 minutes in

 

[dobbslc]

Cheers lads, that should get me sorted

 

[armalites]

Sheet of A4 paper, fold in half and make sure you have a sharp crease then fold in half again making sure you have the edges of the crease lined up. Cheap and quick 90 degree check

 

[Wendelspanswick]

Use a mill and set the stock on the bed. Use the quill with a clock and run up and down the blade.

I use my mill to true up the blades on cheap squares.

 

[chris y]

Use a mill and set the stock on the bed. Use the quill with a clock and run up and down the blade.

Only if you have first squared up the head using a clock mounted to the quill and rotated around on the bed.

 

[dobbslc]

Turns out the piece of skirting I cut must have been on the **** in the saw as the blade is cock on square!

I just have to buy the right size architrave to match the skirting now, seems 14.5 mm architrave doesn't look to good next to 18mm skirting.....
Bad day very bad day!

 

[Maker]

Just blend it in with polyfilla.

That's what whoever lived here last did.