Bridge City ToolWorks Combination Square - Is it as accurate as they claim?

Bridge City claims an accuracy of +/- 0.002 inches for their combination squares. I bought a 6 inch one to see what they are all about, and to test that claim. The video gives my initial reactions about the square and a test of its accuracy. I also compare its accuracy to my other 6 inch combination squares, including the Starrett discussed in an earlier video which I have now improved a factor of 2.5 with about an hour of hand work.
The accuracy was tested by measuring the squareness 5 times at each of 4 configurations for each square. That is, the configurations were cycled through 5 times to produce the data. The result plot shown in the video depicts the means and standard deviations of the 5 determinations.

[@ozyrob1]

I just happened onto your channel. I noticed you've only made 4 videos but 2 new ones very recently. Nice content and advice. I hope you make more. Thank for doing this.

[@practicalmetrology8599]

Thank you for your comment. I appreciate your interest.

[@melgross]

I have one of theirs for woodworking. It’s more comp,exchange this one is. It’s very well made and quite precise. I measured it in my machine shop. The point of my post though is that it’s engraved with laser. Did you check? Laser engraving looks different from either mechanical or chemical engraving.
I’d like to say that I never rely on these types of squares for anything other than a rough guide. My mill will square off the parts I’m working on. If I really need to mark off a parallel line I use my granite and a height qauge with scriber tip. The granite plate is indeed flat.

[@practicalmetrology8599]

Thanks for your comment, Mel. I really appreciate your interest.
I looked again, and you are correct. The scale is coated with some sort of mottled gray material, and the marks are burned into that layer to a small depth that can be seen clearly with a 20X loupe. I can't feel the engraving with my fingernail, but it is definitely there.
Now the question is, how robust is that mottled gray coating? I didn't want to do any sort of really destructive testing, but I did rub a small portion of the scale with a pink rubber eraser, a blue scotchbrite pad, and a green scotchbrite pad in turn. With the green pad, I could start to see scratches appearing in the coating, but the marking I was rubbing over remained clearly visible. Overall, that's good enough for me!

[@airnashville3883]

Like your previous comment, I ran across this by accident. I know the guy who started BCTW; John Economaki. He's still involved but, it's entirely an import company. They specialize in "bling" for the woodworker. Their tools are a horrible value for the money and are made to sit on the wall an be pretty.

[@practicalmetrology8599]

Thanks for commenting! Cool that you know the founder. I would not pay full price for them, but their e-mail flash sales change the value proposition quite a bit (for me) on some of the tools. I haven't pulled the trigger on any others so far, though.