Hello All,
I'm buying an engineer's square to set up some woodworking machines and I am wondering what the accuracy of the title standard is?
BTW - Any recommendations on which square to buy? Thanks.

If you want one that is very accurate, get a Moore and Wright square. These will be more than sufficient for engineering purposes.

As you will be using it to set up woodworking machines then companies like RDG Tools sell good quality squares.

It is important to know that a square may not be accurate on both it's inner and outer edge, usually just the outer edge, so if it is important that both edges are accurate, check the Conformance Certificate.

I would avoid buying a second hand square as if they are dropped it can knock the accuracy.

As stated get a quality manufactured item M&W or Starrett and you won’t go far wrong. Avoid Chinese etc.

Thank you SS. I have been looking at M&W as I know they are a well established firm, I knew of them when I was doing my apprenticeship at Linwood. How do I see the Conformance Certificate?
I certainly wouldn't buy second hand,

Am fairly sure that M&W give full details on their products on their website.

Have a look at:


https://www.bowersgroup.co.uk/product-range/moore-wright/4003-traditional-engineers-square.html

Thank you Scrambled. This doesn't give angle tolerances but I have phoned Bowers and two very helpful people are looking into BS939 for me. The details on the site you sent give the parallelism of the blade and handle which is good but not quite what I was looking for. Cheers.

Bowers have just got back to me. The tolerance at the blade end is six tenths of a thou., so should be accurate enough!

Good enough for anything I do on a milling machine!