For more information on the square, see our beginner site Common Woodworking.

On Sunday morning my students and I met at 8am to check out the local car boot sales. There wasn’t much there, but I found two squares for £1.00.

As I sanded away the rust from the combination square the name of the maker emerged and I discovered a Rabone Chesterman square model 1812.

The second square was by Crown of Sheffield here in the UK; not old but sound, of good steel, pleasing brass and solid beech. Now, as you can see, they don’t look much really, but let’s look at the wretched things a little more closely. Say you’ve got little money and  and need a square as part of your new kit. It would be easy to snub these two, accepting that first appearances count. Within a few minutes the squares started to look a little healthier and once de-rusted and checked for truth I found them both dead square*.


Fine surface pitting is soon removed by abrasion with 250-grit paper and further refined to about 400-grit. A spot of oil over all surfaces coats the steel to prevent ingress of moisture.




The wood stock on the Crown square had no finish and so I applied three coats of shellac followed by furniture polish applied with steel wool and buffed out with a shoeshine brush.


*I have made it a policy never to admit a non-square square to ever remain in the shop so it’s now the square is tested for absolute truth.



Here are the end results of my work



  1. William on 28 August 2012 at 5:31 am

    excellent post Paul. This has been helpful. One thing… How do you true up a square?

    • Paul Sellers on 28 August 2012 at 10:28 am

      Will post on this today. A few drawings I did in my journal some time past will help the explanation.

  2. Paul Sellers on 8 June 2013 at 6:02 pm

    They can be fixed as long as the beam (blade) is straight and hardened steel. The point within the stock where the beam edge slides against and is locked to the stock can wear out of square and this can be filed square with the edge of a thin file.

  3. Bryan Lovquist on 26 May 2018 at 1:36 am

    Good morning Paul

    Have you done or would you be interested in doing a post on how to “fix” a square particularly a combination square which is not square? Do you find that there is seasonal movement in squares made of dissimiliar materials ie wood, brass, steel? And if so, are these types of squares even worth keeping due to lack of confodence in their accuracy?


    • Paul Sellers on 26 May 2018 at 9:17 am

      Wood has a natural propensity to movement and generally I have found wood and metal tri squares to be mostly unreliable in squareness retention full time. Correcting an out of square combination square is unnecessary of you have paid for the kind of quality a good square requires. Though £100 plus for a guaranteed accurate square seems a lot it’s not. The square is the single most important tool in the hand tool arsenal. All other tools take their reference from this single tool.

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