Machinist squares

[Jr5]

As I’ve posted recently. My 2” square

 

[neophyte]

In my [very limited] experience, machinists squares get banged out of square easily. So, I've never bought one. In fact, I've passed on a number of them over the years. It would be overkill for my mostly woodworking anyways. On the other hand, I would be curious to learn how the old timers maintained and checked theirs.

To check a square, you need a precision high accuracy straight end, slightly longer than the square, (although twice as long would be fine).
You also need dome high accuracy machinist squares.
The high accuracy squares should only be kept for checking other metrology equipment, and very carefully kept, without banging, and properly oiled.
You use the straight edge to check the flatness, inside and outside, of your “daily use” machinist squares.
Checking all measuring surfaces, by holding the straight edge up to the squares surfaces, and shining light from behind, since any deviance will be shown by the light.
This checks the surfaces for flatness.
If all the surfaces check out as flat, then you use your high accuracy “reference” squares, to check for square, inside and outside.
Again, the “reference” squares should only be used to check other metrology equipment.
Also check for “wiggle” between the blade and the thicker handle, possibly while using your reference square.
The parallel accuracy of the square blade can be checked with a finely graduated micrometer, but this should be done after checking blade flatness.
most manufacturing companies that had a lot of machinists probably had one or more individuals who kept highly accurate metrology references just to check tools in daily use, or a service they sent tools out to for the same purpose.
The problem for an individual starting out, is affording both a high accuracy reference scale to check other tools, and also the tools used in daily use.

Most squares used for woodworking and cabinetmaking used to have a metal blade riveted into a wood handle.
While properly cured wood can be fairly stable, the accuracy expected was way different than what is expected for precision machining.

Stanley used to make aluminum carpenters squares, and the was dome guy who would check and correct the squares using I think a hard maple mallet and hard naple anvil, and would bang the corner intersection towards the inside or outside depending on how the square was out.
Starrett would hand would check their precision square in a darkened room against a very high precision certified gauge block, and hand correct any that were off by hand.

 

[neophyte]

As I’ve posted recently. My 2” square

These small die makers square are incredibly useful.

 

[JradM]

Affordable grade B squares (less than 0.001" deviation per inch over the entire length of the blade) at Lee Valley:



Starts at ~$15 CDN for a 2" ($12.50 USD) up to $33 for an 8".

 

[JradM]

Also, check out these precision double squares. Made in the USA, accuracy guaranteed to be better than 0.001" per inch and <$50 USD.

 

[tjansson]

I have bought my "affordable" machinist squares from McMaster. I have some faith in their vendor selection and that I'm not getting ****. Their current "high accuracy" 6x4" square is made in India, 0.0006" accuracy, and $36.

 

[slowtwitch73]

Comprarator, cylindrical square and a good table is the way to check a square.

 

[JradM]

I have bought my "affordable" machinist squares from McMaster. I have some faith in their vendor selection and that I'm not getting ****. Their current "high accuracy" 6x4" square is made in India, 0.0006" accuracy, and $36.

Do you know who is the manufacturer? I can't order from McMaster as an individual in Canada.

 

[johnre]

I bought this reasonably-priced Japanese made Shinwa Sokutei square #62081, but checked it with a buddy’s Starret #20. It was dead on.

 

[AEAdam]

Older made in Japan Mitutoyo is high quality. Nothing plastic, new stuff is fine too.

That said, I definitely prefer Starrett’s rulers, they’re excellent.

For squares I prefer Starrett, I check them using a scraped in master square and a granite surface plate or on a scraped in box beam.

That's the right way to do it!

I really like Mitutoyo and have many many tools of theirs. At least some of their combination squares are made in Brazil, which I didn't think were quite as nice as the Japanese models. Not everything from Brazil is bad. But I didn't like the Mitutoyo combination square set I had from there.

 

[AEAdam]

Do you know who is the manufacturer? I can't order from McMaster as an individual in Canada.

Screw them! Canadians should be ordering from Lee Valley. They are top notch. I didn’t know they were making their own squares. I wouldn’t hesitate to buy from them.

 

[dscheidt]

Also, check out these precision double squares. Made in the USA, accuracy guaranteed to be better than 0.001" per inch and <$50 USD.

Those look like the PEC double squares I have.

 

[JradM]

Another place I would look, if I wanted something more premium, is Cardon Tools. They have lots of NOS Moore & Wright and they also carry Starrett, PEC, FACOM, Brown & Sharpe... and GJ members get 20% off with code "GARAGEJOURNAL20".

It's a Canadian retailer, but they sell to the USA too (which might be an advantage given our relatively weak Canadian dollar at the moment).

 

[neophyte]

Another place I would look, if I wanted something more premium, is Cardon Tools. They have lots of NOS Moore & Wright and they also carry Starrett, PEC, FACOM, Brown & Sharpe... and GJ members get 20% off with code "GARAGEJOURNAL20".

It's a Canadian retailer, but they sell to the USA too (which might be an advantage given our relatively weak Canadian dollar at the moment).

Do they have an eBay store under a different name ?

 

[tjansson]

Do you know who is the manufacturer? I can't order from McMaster as an individual in Canada.

Nope, with McMaster, they won't tell you the manufacturer, except for certain items, like Starrett and Mitutoyo products, respirator cartridges, lubricants. I bought my square a long time ago from them (could be a different supplier now) and I don't think it's branded.

 

[Fixr]

Nope, with McMaster, they won't tell you the manufacturer, except for certain items, like Starrett and Mitutoyo products, respirator cartridges, lubricants. I bought my square a long time ago from them (could be a different supplier now) and I don't think it's branded.

FWIW, Years ago I did have success getting McM to tell me the brand of an item once or twice, and when I was buying wrenches they told me they would be either Wright, Williams or Armstrong.

 

[bpwoodworking]

If you provide them with a very specific request they will usually let you know the brand.

I also often simply guess based on COI and item type. As example, They sell a lot of knipex stuff at excellent prices but it’s listed without the brand.

 

[JradM]

Do they have an eBay store under a different name ?

I don't know, sorry.

 

[Mb4]

You would be better off starting with a high quality combination square, with various length blades and a couple of Fireball Tool welding squares instead of machinist precision squares. I've got Starrett squares in 4" and 6" heads with 6", 12" and 18" blades in 16R graduations. I also have a Mitutoyo set with the square, v head and the protractor. The machinist squares I have are relegated to being used for precision layout work, for the mill.

For welding, I've got several of Jason's squares, but haven't had a chance to use them yet. Everyone that I know of that has used them, loves them.

Starrett heads and blades can be found on evilbay relatively inexpensive, but be sure to look close at the blade photos for wear and damage.

Great answer! A Starrett combination square is accurate to .002" which is close enough for 90% of the work that you most people - profesisonals included - would be doing. Same for the Mitutoyo or the PEC (which makes combination squares for Mitutoyo).

 

[Mb4]

All of the 123 blocks I have, all cheap imports, are as square as anything I have. I did get one that wasn't square, one edge was not parallel to its opposite. still square enough to build a house, not good enough to set up a saw or something.

1-2-3 blocks that aren't 1-2-3 or square aren't 1-2-3 blocks. I agree that precision comes at a price, how precise do you need to be? - but the garbage coming out of China is absurd.

 

[bpwoodworking]

Some of the Chinese blocks are good, I use them for welding fixtures and for bolting down as an end stop on the mill. Stuff I don’t want to use the precious stuff for.

The holes don’t coordinate like the good blocks, so they have limited uses.

I have a few from Suburban tool and a few others from mitutoyo when high precision is needed or when they need to be bolted together.

Used fixturing stuff on eBay is a great way to go. I’ve gotten stuff for cheap because it’s lightly used.

 

[Mb4]

Just looked this up for you guys:

Starrett #20 .0001”/6”
PEC .0005-6/6”

Starrett combos and doubles: Starrett doesn’t provide squareness specs for their combos. They have to be clean, adjusted correctly and they are subject to wear. My experience with them is they are more than good enough for woodworking, but I’m not sure I’d set up a precision machine with one.

Starrett combo blades are thicker than others’. This means you can buy a Starrett 12” combo and put 18” or 24” PEC blades in it, but you can’t put Starrett combo blades (rules) in others’ heads.

Starrett combination squares are accurate to .002". It doesn't get mentioned often, but it's important to have a case for any precision square. Starrett makes nice mahogany cases you can buy for their combination squares. They also have less expensive plastic/foam lined caess too.

 

[Johnny chaos]

Well I took everyone’s advice and bought what was recommended, eBay for Starrett and HJE for PEC

 

[cvairwerks]

Something to keep in mind, is that the blades on the adjustable and double headed squares can be swapped for different lengths and scale graduations. I typically use 16R scales.

 

[RTM]

Something to keep in mind, is that the blades on the adjustable and double headed squares can be swapped for different lengths and scale graduations. I typically use 16R scales.

Not "generally" at least in the Starrett and B&S world. Pretty sure in PEC 4 & 6" can't swap, never seen a 9"

The 4", 6", & 9" scales can't swap sizes, only graduations. The 12" can go to 18" & 24" scales and different graduations on each size.

 

[cvairwerks]

Not "generally" at least in the Starrett and B&S world. Pretty sure in PEC 4 & 6" can't swap, never seen a 9"

The 4", 6", & 9" scales can't swap sizes, only graduations. The 12" can go to 18" & 24" scales and different graduations on each size.

Hmm...I swap the scales on my Starrett adjustables and double heads all the time, and have done it for years. Engineering squares are different, as they are all fixed blades. The double head has 6 different lengths available and the bigger heads have 11 different lengths.

 

[RTM]

Hmm...I swap the scales on my Starrett adjustables and double heads all the time, and have done it for years. Engineering squares are different, as they are all fixed blades. The double head has 6 different lengths available and the bigger heads have 11 different lengths.

Do you mean between swap scales double and combo, or on a combo, between 6" & 9"?

I'm referring to the latter, tho I can see the former as being me misunderstanding your thoughts.

 

[cvairwerks]

All of the heads that are 4" and larger share the same scale set, with the exception of the Junior and Student heads. The double heads share their own set of various length scales. I haven't tried them, but the Junior and Student heads may share the same scales as the double heads.

 

[AEAdam]

Well I took everyone’s advice and bought what was recommended, eBay for Starrett and HJE for PEC

That S#20 looks perfect. Hopefully wasn't too expensive. I see original grinding marks on the blade and stock. I would clean it, oil it, and put it away. I have slathered mine in vaseline and put them in ziplock bags. Maybe someone here has a better suggestion.

 

[elmer]

Do any of you guys know anything about these squares ? Bought them at an auction today, they appear to be NOS in the original box.

 

[Ohio Andy]

I use my engineering squares all the time. They are very accurate for the price; especially if you compare them to my other squares made by starett, vespers, pec, and others. A specific use for each. Unless you have a specific need, money to burn, or really like fine tools, you probably don't need a $600 vespers square.