Cheap square angle tolerance

[transatlantic]

I would gladly pay a little more if there was a guarantee of squareness, so I am please to learn about the engineering squares and their standards that people have mentioned above. I may have to go shopping...

Unfortunately the standards only apply when bought from a decent supplier. I made the mistake of buying 3 engineering squares from Toolstation (yeah I know) ... and all three were so far out it was laughable.

They handn't been bashed or anything, they'd just been manufactured very poorly. All three. I don't see how it's possible to get them so bad.

 

[sammy.se]

.....I have filed my cheap aluminium roofing square......

It's much quicker the traditional way with a hammer and punch.

It's one of these, rather than the large 'L' shaped framing (?) square:

 

[MikeG.]

:lol: :lol: Yeah, that might take a while with a punch! :lol:

 

[MattChow]

Thats the same as the one i filed down too. Took about 1mm off the heel in the end....

Did you make the 45° accurate too?

 

[D_W]

I thought I just posted to this thread....guess not.

if you can draw two long precise marks off of a straight edge any way that a square can be oriented and they appear to be parallel, that's a good practical standard.

If some squares are out of kilter, you can adjust them or use them for narrow work (like checking jointed edges for square, or small items). Sometimes it's nice to have a few squares that aren't really that perfect so that you don't feel obligated to baby them.

10+ years ago, I found a 24" starrett no 20 for $24 or $25 or something and somewhere around $40 to ship ("won" on ebay) and then used a friend's certified square to check that it's still true (it is).

https://www.transcat.com/starrett-20-24 ... KwQAvD_BwE

That's not practical unless you happen to come across one. The plastic drafting squares check out well against it as a reference if they aren't the cheapest chinese drafting squares/triangles that you can find. I've never checked those.

if I didn't have the monster above, I'd plane a flat edge and just check by making parallel lines. If you can mark two lines close together and you cannot see that they're not parallel, that's a pretty high standard.

 

[sammy.se]

I thought I just posted to this thread....guess not.

if you can draw two long precise marks off of a straight edge any way that a square can be oriented and they appear to be parallel, that's a good practical standard.

If some squares are out of kilter, you can adjust them or use them for narrow work (like checking jointed edges for square, or small items). Sometimes it's nice to have a few squares that aren't really that perfect so that you don't feel obligated to baby them.

10+ years ago, I found a 24" starrett no 20 for $24 or $25 or something and somewhere around $40 to ship ("won" on ebay) and then used a friend's certified square to check that it's still true (it is).

https://www.transcat.com/starrett-20-24 ... KwQAvD_BwE

That's not practical unless you happen to come across one. The plastic drafting squares check out well against it as a reference if they aren't the cheapest chinese drafting squares/triangles that you can find. I've never checked those.

if I didn't have the monster above, I'd plane a flat edge and just check by making parallel lines. If you can mark two lines close together and you cannot see that they're not parallel, that's a pretty high standard.

and only $1800! what a bargain. I think it's cheaper to rebuild all my furniture around 89 degree corners

 

[powertools]

Before anybody goes off and buys an expensive engineers square I would suggest you look at this.

https://www.tyzacktools.com/products/14 ... quare.aspx

Full stainless steel a lot lighter and far cheaper than an engineers square and totally spot on square.
I have no involvement with the seller but the service was good and the square is a pleasure to use.

 

[MikeG.]

It always tickles me how often the same conversations are repeated. How-square-is-square is one we do every few months here, and although the personnel change, the discussion points remain the same.

 

[Racers]

Car boot last Sunday £5

Big square by Pete Maddex, on Flickr

And its square!

Pete

 

[Cheshirechappie]

Nice one, Pete - not bad for a fiver!

When I was still involved in heritage railways, an old chap walked into the mess room one day and gave us a brand, spanking new Moore and Wright 12" engineer's square, still with the manufacturer's grease on it, in the manufacturer's box, with the inspection slip. I made a wooden box for it, and we tucked it away in the machine shop for special occasions only.

 

[Roland]

The method I was taught at school was to mark out with the T-square, then reverse the square and check the marking. This highlights deviations from whatever source: faulty square, non-straight baseline, marking technique etc. I’ve always found wiggly baselines and faulty technique to be more of a problem than faulty T-squares.

 

[MusicMan]

It always tickles me how often the same conversations are repeated. How-square-is-square is one we do every few months here, and although the personnel change, the discussion points remain the same.

Yes ... I keep reposting the most precise and cheapest way to check it at home and people keep ignoring it and rabbit on about 'standard' squares and the meaningless 'spot on' ...

 

[D_W]

I thought I just posted to this thread....guess not.

if you can draw two long precise marks off of a straight edge any way that a square can be oriented and they appear to be parallel, that's a good practical standard.

If some squares are out of kilter, you can adjust them or use them for narrow work (like checking jointed edges for square, or small items). Sometimes it's nice to have a few squares that aren't really that perfect so that you don't feel obligated to baby them.

10+ years ago, I found a 24" starrett no 20 for $24 or $25 or something and somewhere around $40 to ship ("won" on ebay) and then used a friend's certified square to check that it's still true (it is).

https://www.transcat.com/starrett-20-24 ... KwQAvD_BwE

That's not practical unless you happen to come across one. The plastic drafting squares check out well against it as a reference if they aren't the cheapest chinese drafting squares/triangles that you can find. I've never checked those.

if I didn't have the monster above, I'd plane a flat edge and just check by making parallel lines. If you can mark two lines close together and you cannot see that they're not parallel, that's a pretty high standard.

and only $1800! what a bargain. I think it's cheaper to rebuild all my furniture around 89 degree corners

I showed it to my mechanical engineer buddy and he said "they're worthless once they're older".

Good! otherwise, I'd never be able to get one for $25. They're hardened and very tough.

 

[Inspector]

I have a 7" high cylinder square and a granite plate if I feel the need to get silly picky about checking my squares. The company I worked in before retiring used one of the four CMM's (Coordinate Measuring Machine) to calibrate the squares. Doesn't that make $1,800.00 square sound like a bargain?

Pete

 

[MusicMan]

Pete

If you are getting really picky, you have to recalibrate the square annually, and also of course the CMMs!

 

[Inspector]

Well I'm not going to calibrate the cylinder square as not much can change unless you drop it or drag it around the floor and I'm not inspecting anymore or using it for commercial work. If I were I would. The company did have the CMM's (Mitutoyo and LK) calibrated every year by a company that came to the plant. They also checked the milling machines to make sure they were accurate. An error over 20,0000mm adds up. The portable CMM (Faro Arm) and Laser CMM (Faro Tracker) were sent back to the factory every year too. Most all the hand held measuring tools like micrometers, callipers, dial indicators, height gauges etc we did in house.

Pete

 

[That would work]

How many of you have precise temperature control in your workshops?
If not you are wasting your time.
](*,) ](*,) ](*,) ](*,) ](*,) ](*,) \/

 

[Inspector]

I'll put on my white shop coat and go check.

Pete

 

[powertools]

It always tickles me how often the same conversations are repeated. How-square-is-square is one we do every few months here, and although the personnel change, the discussion points remain the same.

Yes ... I keep reposting the most precise and cheapest way to check it at home and people keep ignoring it and rabbit on about 'standard' squares and the meaningless 'spot on' ...

Would you like explain what is meaningless about spot on?

 

[That would work]

Is atmospheric pressure a factor?