Decent Quality 300mm Try/Engineers Square.

[pollys13]

To test face side to face edge squareness.
Been reading try squares can move, if knocked about or due to temperature changes.
So perhaps it would be best to go for an engineers 300mm square, would certified be best for checking face and edge squareness? I have smaller certified squares for checking table saw blade to table square. The surface planer has 10 inch bed.
Cheers.

 

[Trevanion]

All squares can move given enough knocking about or temperature changes, even the engineer's squares.

The trick is to check that your square is indeed square once in a while and totally forget about whatever "certified" nonsense you've come across because all that means is once you've bought one and it isn't square out of the box they'll keep sending you replacements until you're happy you've got a square one.

If your existing square is square and you aren't playing football with it you should be fine.

 

[pollys13]

" The trick is to check that your square is indeed square once in a while and totally forget about whatever "certified" nonsense you've come across "
OK thanks for that.

 

[Cheshirechappie]

In woodwork, a 12" square is the sort of tool you'd use for marking-out large components or checking the squareness of furniture carcases on assembly. A 12" engineer's square is a fearsomely expensive beast, too.

For face to edge checking, something around 6" (or even 4" if using a decent engineer's square) would be most people's instrument of choice. Don't worry about calibration certificates - an engineer's square made to BS939 Grade B (workshop grade) will be more than adequate for even the most demanding woodworker. Doing the old trick of holding the square's stock to a straight-edged piece of timber, drawing a line against the edge of the blade you want to check, then reversing the square and drawing another line against the same edge to see if they're parallel will also be fine.

I agree with Trevanion on this - if you already have a 6"/150mm square, check it as described, and if the lines are as near parallel as dammit is to swearing, you already have all you need.

It may be worth having one good quality square of known accuracy to act as a reference to check the working squares in the very well-equipped workshop, but it's a 'nice to have', not an out-and-out need.

(PS - The 'certified' nonsense isn't nonsense, but it's of relevance to engineering, toolmaking, inspection and calibration, and not to 99.9% of woodworking.)

 

[pollys13]

"The 'certified' nonsense isn't nonsense, but it's of relevance to engineering, toolmaking, inspection and calibration, and not to 99.9% of woodworking. "
Yes I thought that, would be the case, for metaworking. The 6 inch engineers square I have, is BS939 Grade B. So I'll stick with that to check for face, edge square.
Cheers.

 

[MikeG.]

........ The 6 inch engineers square I have, is BS939 Grade B. So I'll stick with that to check for face, edge square........

Yeah, but check it first. It doesn't matter how fancy the specification or the price.......if it's not square it's not square. I tend to check mine if I mark out around 4 sides of a piece of wood and the last two lines don't meet.

 

[sunnybob]

Unless youre building a space ship...... any square is square enough.
If you look up than EN certified rule, it still isnt guaranteed very much.
Find a single flat edge, use the square you have and draw a line the length of the arm using the finest point pencil you have. Flip the square, slide it up to the line, and draw another line the full length of the arm.
If you are now looking at one single line, the thing is square. If not, its not.

I'm now using a little digital box to find levels and angles (wixey is the most famous make, mine is a bit cheaper) and its amazingly usefull. It shows to 100th of 1 degree in several diffent measuring systems. And if it does sometimes not give EXACTLY the same repeatable number, I dont care about 200ths of 1 degree.
Its even got a magnet so it sticks to the saw blade as you rotate the thing. =D> =D> =D> =D>

 

[MikeG.]

Unless youre building a space ship...... any square is square enough.......

Hmmm, well........ hand tool woodworkers need something reasonably accurate, because we mark shoulders on tenons using a square, and what we mark is what we cut. Guys who use machines for accurate work maybe don't need a square that is quite so bang-on as squareness is built into the machine set up.

 

[pollys13]

OK thanks MikeG and sunnybob.

 

[sunnybob]

Mike. I was being metaphorical (hammer) (hammer)
#-o =D> #-o =D>
8)

 

[John15]

Mike. I was being metaphorical (hammer) (hammer)
#-o =D> #-o =D>
8)

Even so, dangerous advise to an novice woodworker.

John

 

[AJB Temple]

See my thread just now about an Axminster 'precision" adjustable square that arrived today. 2.5mm out over 300mm. That is more than enough to create real problems when setting out joints. A square is either properly square when checked, or is not a square at all and useless as a tool.

 

[sunnybob]

Mike. I was being metaphorical (hammer) (hammer)
#-o =D> #-o =D>
8)

Even so, dangerous advise to an novice woodworker.

John

The next paragraph explained carefully how to check any square for trueness regardless of certification.
If somebody cherry picks one line over another in a reply, then they arent really paying attention.

 

[John15]

Mike. I was being metaphorical (hammer) (hammer)
#-o =D> #-o =D>
8)

Even so, dangerous advise to an novice woodworker.

John

The next paragraph explained carefully how to check any square for trueness regardless of certification.
If somebody cherry picks one line over another in a reply, then they arent really paying attention.

Yeah, right.
John

 

[Yojevol]

See my thread just now about an Axminster 'precision" adjustable square that arrived today. 2.5mm out over 300mm.

Are you refering to Axminster's 'combination' square? If so it doesn't claim to be adjustable apart from being able to move the rule. Axi do offer an Adjustable Square but it's only a small job.
I obtained something similar about 15 years ago -

The blade is mounted on a steel pivot which is just discernable in the pic and it is adjusted with an Allen Key in the small hole in the stock. So it can be as accurate as I want it to be.
If anyone is interested in making an adjustable square have a look at this. It might give you a few ideas to get you started.
Brian