Decent try square

[custard]

Whoa, stall the digger.

Very funny.

Yes, the majority of full time furniture makers that I've met use combi squares. They might have a fancy engineer's square in a box to check their combi squares against if they've dropped them, or they may have a 4' x 2' draughtsman's square for drawing up plans, but pretty much all of their day to day furniture making work is done with combi squares, and I guess at least half of those are Starrett combi squares.

 

[Cheshirechappie]

Should anyone have free access to British Standards, or be willing to shell out a not inconsiderable sum of money, the standards for carpenter's squares and engineer's squares (not including adjustable squares) are as follows;

BS3322 - 1981 Carpenter's Squares - https://shop.bsigroup.com/ProductDetail ... 0000072804

BS939 - 2007 Engineer's Squares - https://shop.bsigroup.com/ProductDetail ... 0030163790

The Engineer's Squares standard covers try squares, cylindrical squares and block squares to grades AA, A and B (calibration, inspection and workshop, in effect). Scrolling down to read the description shows what the standard covers, but someone will have to pay up to find out the numbers!

 

[MarkDennehy]

Whoa, stall the digger.

Very funny.

An actual idiomatic saying around these parts believe it or not...

Yes, the majority of full time furniture makers that I've met use combi squares. They might have a fancy engineer's square in a box to check their combi squares against if they've dropped them, or they may have a 4' x 2' draughtsman's square for drawing up plans, but pretty much all of their day to day furniture making work is done with combi squares, and I guess at least half of those are Starrett combi squares.

Huh. Would not have guessed it. I always thought combisquares were just a kind of quick-and-dirty tool, that if you ever actually needed square (even to within normal measurements) you'd use something else.
I may have been influenced in that by the cheap silverline type of combi square I got originally, as compared to the cheap engineers squares I got originally. The latter were spot on in a reference-edge-and-flip-it-over test, but the combi square was... well, I put it in the bin, that's how good it was.

I suppose if you're spending three figures on one made by starrett or M&W it's a bit better, but my head just doesn't want to trust them and I keep reaching for the engineers square from proops over even the M&W sliding square that I have here.

 

[Phil Pascoe]

Here's the thing about squares. When a square is certified "square" what is it that's actually being certified?

Here's a diagram that illustrates what I mean,



Is it edge A to B that's square within a specified tolerance? Or C to D? Or A to D? Or B to C? Or indeed all of them?

I read long ago (I forget where) that it is only the inside A - B that is guaranteed square.

 

[bugbear]

Whoa, stall the digger.

Very funny.

Yes, the majority of full time furniture makers that I've met use combi squares. They might have a fancy engineer's square in a box to check their combi squares against if they've dropped them, or they may have a 4' x 2' draughtsman's square for drawing up plans, but pretty much all of their day to day furniture making work is done with combi squares, and I guess at least half of those are Starrett combi squares.

Combination square are very convenient and versatile, and a well made combination square can be "within tolerance" for many wood working operations.

So I'm not surprised.

My own day to day square is an old and battered 12" M&W combi square. I've retrued it (with files, scraping and SiC) using a 2-4-6
block and a surface plate. The accuracy is still no more than OK, but I get the heft and handling of a well made tool.

In truth, being a car boot hound, I have quite number of nice square, of varying types, grades and sizes.

BugBear

 

[MikeG.]

........would you really depend on a combi for square over an engineers square?

Absolutely! It's indispensable, and as I said, mine is the most accurate of my squares.

 

[bugbear]

I read long ago (I forget where) that it is only the inside A - B that is guaranteed square.

The official document is up-thread for details.

BugBear