Welcome! Forums General Woodworking Discussions Tools and Tool Maintenance/Restoration Fixing an out-of-square combination square

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    Chris Bunney

    Hi all,

    I have a fairly good quality metal combination square (the type with the sliding rule and a cast stock with 45 and 90 degree angles).

    However, I notice recently that it is slightly out of square. I found this out using the trick of putting the stock up against a flat edge and drawing a line against the rule, then flipping the square over and doing this same: the lines diverged very slightly.

    What’s the best way to tune up this kind of square to get it back to perfect squareness again?



    Chris - Exeter, UK


    Have you seen this? http://youtu.be/bf40pMe0osk

    Matt McGrane

    The video was right on. Many combination squares have small leveling tabs on either end of the slot where the ruler slides. These can be filed or sanded down to bring your square back into square. Look carefully (and maybe with a little magnification) for these tabs in the bottom of the slot. And sand or file very carefully, checking the square often, so that you don’t get it out of square the other direction.

    Good luck.

    Matt, Northern California - Started a blog in 2016: http://tinyshopww.blogspot.com/

    John Purser

    I’ve done this on three or four squares now and every one could be brought to square using this method. I use needle files and they make it a very simple job.

    Matt’s right. All the ones I did had small tabs on each end of the channel which makes filing or sanding the square back into square extremely simple.


    John Purser
    Hubert, NC

    mike melendrez

    I have fixed 4 old squares that way. Workes great and was fun to do. I used the steel beam or ruler on the last 2. The tabs are very soft so the edge of the beam will scrape it very easy. Go slow and keep checking it.

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