Starrett 18” precision square

MetalArtistCandy · Jun 28, 2021

Well I bunch a bunch of machinery and tooling today. The one thing I do not think I would use is this 18” machinist square. Just a little big for what I would be doing. I have the smaller ones, and one about that size for woodworking.

I see them sell on ebay from $300-$500, but man those brand new prices are insane! I can now see why they sell so high on ebay.

Im thinking about selling this one if anyone is interested.

How many of you guys use these 18” and larger squares?

eKretz · Jun 28, 2021

They are generally used on larger machinery. I used to use squares that size (and larger) on big HBM work for setup. For small work they aren't really necessary.

4GSR · Jun 28, 2021

That 18" Starrett square sells new for way more than $500. The big question is, what can you really get for it? And do you have a way to check if for being "square"? It that can be guaranteed, I'm sure $300-500 is a good price. I have a 18" B & S square I picked up for $50 bucks few years back. Had it check to be within .0005" for the full length of the beam. It came with the wooden holder to protect it from reasonable damage. does yours have the wooden holder?

SShep71 · Jun 30, 2021

I have been looking for one similar to this size, if you decide to sell it or trade it let me know.

metalmagpie · Jun 30, 2021

I have one about 14" blade. Not Starrett, though. I use it a lot. I used it when I had my shaper to square the vise to the cross-slide axis. I use it on the mill to quickly get a part close to square. I use it to set my horizontal bandsaw's fixed jaw square to the blade. It wasn't super accurate but then I gave it a tuneup grind on my surface grinder and now it's pretty good.

metalmagpie

Laverda · Jun 30, 2021

What people ask for on Ebay and what they sell for are two different things. I have Starrett precision squares in 3", 6", 12", 18" and 24". All used but in very good condition. Most I paid for any of then was about $100.

If there is any evidence of them being dropped on the floor, they are scrap.

eKretz · Jul 1, 2021

Not really, they can be re-ground. They really aren't that complicated to check either. We used a fixture with cam rollers mounted on eccentric shafts for checking squares on the work floor.

EPAIII · Jul 1, 2021

It may be asking a lot, but can you post a photo or sketch of that checking procedure?

Or a web reference?

eKretz said:
Not really, they can be re-ground. They really aren't that complicated to check either. We used a fixture with cam rollers mounted on eccentric shafts for checking squares on the work floor.

eKretz · Jul 1, 2021

I don't have any web reference, just personal experience. I've attached a quick sketch of the apparatus we used. The square's vertical beam was brought into contact with the bottom roller, then all the subsequent rollers were adjusted with the eccentrics until they came into contact. After this, the square was moved over so that the opposite side of the square's beam contacted the rollers or reversed and placed into contact from the other side (only works if the rollers are all exactly the same diameter and/or the square's beam is parallel top to bottom). Contact could be checked with a feeler gage or several equal sized pieces of shim could be inserted and checked for a snug fit. Place rollers as needed.

For this method it's important that the table surface is flat and the checking fixture upright is fairly rigid.

Tony Quiring · Jul 2, 2021

The quick poor man's check is to place it on the edge of a flat table and put another straight edge along the blade.

Clamp straight edge to table optional.

Flip square over and push against the straight edge and it should still be square, if not it isn't.

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TGTool · Jul 5, 2021

Tony Quiring said:
The quick poor man's check is to place it on the edge of a flat table and put another straight edge along the blade.

Clamp straight edge to table optional.

Flip square over and push against the straight edge and it should still be square, if not it isn't.

Sent from my SAMSUNG-SM-G930A using Tapatalk

If I'm following correctly that only proves the two squares are identical or they're not. They could both have the same error.

The process Ekretz shows does proves squareness. A similar thing can be done with an indicator. For instance, if the fixture he shows had an indicator fixed at the top and a single roller at the bottom, the indicator could be zeroed, and reversing the square would show whether the square was true, or how much it was off and in which direction.

eKretz · Jul 5, 2021

The straight edge method works too, just gotta move to the other side of the straight edge or opposite side of the square beam. The nice thing about the fixture setup is it's almost hands free. Much easier to use a feeler gage that way than the straight edge method in my experience. The indicator added to the fixture (or multiple) is good to speed things up too. Generally we only checked them once in a while so weren't too concerned with speed. Most of the stuff we made in that shop wasn't too picky - very large fabrications used in the steel mills.

JohnMartin · Jul 7, 2021

I saw them checked some years ago at Starrett, by an old toolmaker in a private room to which he allowed few access. Surface plate and several master squares, which he often checked against each other. A vertical fluorescent tube behind, blocked off except for a narrow slit. Of the larger squares they sold, he tested every one.

Tony Quiring · Jul 7, 2021

TGTool said:
If I'm following correctly that only proves the two squares are identical or they're not. They could both have the same error.

The process Ekretz shows does proves squareness. A similar thing can be done with an indicator. For instance, if the fixture he shows had an indicator fixed at the top and a single roller at the bottom, the indicator could be zeroed, and reversing the square would show whether the square was true, or how much it was off and in which direction.

Who said 2 squares?

One square checking itself.

You flip it over and if not perfectly square the blade will be different angle.

You use anything straight along the blade as a reference, for wood working just draw a line...

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4GSR · Jul 8, 2021

JohnMartin said:
I saw them checked some years ago at Starrett, by an old toolmaker in a private room to which he allowed few access. Surface plate and several master squares, which he often checked against each other. A vertical fluorescent tube behind, blocked off except for a narrow slit. Of the larger squares they sold, he tested every one.

Funny you mentioned that. I heard the same thing from a Starrett tool salesman back in the late 1970's. Also was told when it was not "squared" they took a ball peen hammer and peened the blade until it was square. I would think they would have much better manufacturing processes now days.

eKretz · Jul 8, 2021

I should hope so...

rimcanyon · Jul 9, 2021

I have used the ball peen method to square up framing squares. You strike the square along the diagonal from inside to outside corner. Striking close to the inside corner opens the square up and striking close to the outside corner closes it. You can get pretty good at adjusting old squares, the kind that are made from tapered stock, thickest at the corner.

mike44 · Jul 12, 2021

I am a retired carpenter and your description is how I was taught. I only had to adjust a framing square twice in almost 60 years. To check the square the long side is placed against a saw table edge and magnets on the table edge hold the square and align the blade to the edge. This is done near the miter slot. It will be very apparent if the square is off at all. I believe the table saw slots are extremely close to square off the table edge. Even inexpensive saws are machined to tight tolerances in my opinion.
mike

stephen thomas · Jul 12, 2021

When acquired sometime in the past, i modified the ram in my 3T shop press to take 1/2" shank tools.
So a ball nose tool can be inserted, or a "cross pein" pattern, and used against a hard platen, for more controlled pressing (peining) of things like square corneers/edges.

Alternately, in the past, i squeezed the blade with a dowel pin (pin is flat/edgeways/using radius) in a vise. This actually lets you get right at the edge in a controlled fashion. Takes very little displacement to move things. Best to go lightly over a short span or it will create a "kink". Dowel pins can be any size from about 5/32" to maybe 5/16"

Good squares i plane, grind, or scrape.

smt

John Garner · Jul 12, 2021

The reversal test for perpendicularity depends on the try-quare blade edges being parallel -- or the cylinder square being cylindrical -- within very narrow limits.

Starrett 18” precision square

Aluminum

Diamond; Mod Squad

Diamond

Hot Rolled

Titanium

Cast Iron

Diamond; Mod Squad

Diamond

Diamond; Mod Squad

Titanium

Titanium

Diamond; Mod Squad

Hot Rolled

Titanium

Diamond

Diamond; Mod Squad

Diamond

Aluminum

Diamond

Titanium

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