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View Full Version : Found Starrett Machinists squares today.


Tony Shea
08-09-2012, 4:29 PM
So I was going through my girlfriend's grandfather's tools today and the only two things of interest were a pair of Starrett all metal machinist squares. There was a #20 9" version (which is a very heavy chunk of hardened steel) and my favorite a No. 55 4.5" square.

The No. 55 has both edges of the beam beveled which makes checking for light peaking through a bit easier. It also comes with a box that is right from Starrett and looks to made of mohagany. I really like this square's weight and design. Should make a very nice and extremely accurate try square in my shop. But due to the bevel it may not be a very good tool for marking lines across a board.

The No. 20 is also a nice square but just is a bit big for my purposes. I get plenty of use out of my 12" combination Starrett but this No. 20 is a big chunk of heavy tool steel. Just not a very ergonomic tool in a woodworking shop. Will have to put it up for sale so someone can get better use out of it.

And both squares have checked out to still be very accurate, the No. 55 looks brand new as well while the No. 20 is not quite as shiny. No rust but the shine has dulled with age. And they both produce a beautiful ring when tapped against metal which tells me the solder joint is still holding up very well. Just thought I'd bragg a bit about my find and gift. Also any info on either tool is def welcome.
george wilson
08-09-2012, 5:25 PM
Just keep the same angle on your scribe for the beveled square. With a beveled square,it is easier to see .0001"(a "tenth") of light. Can be done with a regular square,too,but with just a bit more care. And you should use care working to tenths anyway.:)

You should feel the weight of my 24" machinist's squares!! Be very careful to not let one slip out of your hand.
Jim Koepke
08-09-2012, 9:43 PM
You should feel the weight of my 24" machinist's squares!! Be very careful to not let one slip out of your hand.

Really, it could hurt if it hit your foot. :eek:

jtk
Bruce Page
08-09-2012, 10:01 PM
Congrats! I have a No. 20 that I bought new in 1970. It has never been banged or dropped and is still as accurate as the day I bought it.
Tony Shea
08-11-2012, 5:33 PM
Just keep the same angle on your scribe for the beveled square. With a beveled square,it is easier to see .0001"(a "tenth") of light. Can be done with a regular square,too,but with just a bit more care. And you should use care working to tenths anyway.:)

You should feel the weight of my 24" machinist's squares!! Be very careful to not let one slip out of your hand.

I can just about imagine how heavy the 24" square is. I read an old fine woodworking from the 80's and saw an article on squares and how they are made. The author visited the Starrett factory and talked about how they were made. But the thing that struck me was that they make a 36" version of the square. I wouldn't even know how to begin to use such a beast of a square. And they will also make a special order square as big as 6' if you really wanted one.
Adam Cherubini
08-27-2012, 6:02 PM
These squares are master squares designed to check other squares/tools, not for layout work. Use your combination squares for layout tasks.

The larger no 20s and 55s are used on the bench, stored in great wooden hockey stick shaped boxes. The boxes have lids such that the business faces of the squares can be accessed with the squares remaining stationary.

A new 9" no. 20 is worth hundreds of dollars. Second hand, they are worth a fraction since real machinists prefer new tools they can trust, not second hand tools that may have been dropped or sanded by some knucklehead trying to "clean" them. New, these squares are precise to .0002"/6".

Pits or slight surface corrosion present no appreciable loss to the accuracy of these tools. Knicks or burrs do. You can dress away knicks with extremely fine Arkansas slips (I have some I use for my carving tools). You have to be very careful to follow the surface, apply even pressure and use just a few light passes. Only do this for a knick that has generated a raised burr (displacement), never for pitting. Store these tools in a dry clean place, and oil after each use.
george wilson
08-27-2012, 10:09 PM
I do a lot of metal and machining work,too. The squares come in handy.