Making a Square Square





Introduction: Making a Square Square

This is a good brand name square my father bought. When I used it I discovered it was not actually square. The rivet and brass system for attaching the blade to the handle is very good. No amount of tapping would change the alignment.

Step 1: Checking a Square

If you want to check a square, you could hold it up to another square, but that one could be inaccurate, too.

The dark brown piece of wood in the photo is the end section of a piece of veneer plywood I have been carrying around for several decades. The white paper arrow points to the factory cut edge of the sheet. This makes a trustworthy straightedge. The white chipboard piece of shelving raises my work surface for this Instructable to the same height as the plywood straightedge.

Step 2: Lay Down a Piece of Paper and Tape It.

This is a piece of clean scrap paper. I taped it so it does not move.

Step 3: Score a Line.

Hold the leg of the square firmly against the straightedge. With a fine point pen, mark a line along the other leg of the square for its entire length.

Step 4: Flip the Square

In geometry it is true that two lines perpendicular to the same line are parallel to each other. Flip the square over and score a second line. Make it a tiny fraction of an inch away from the first line. If the square is truly square, the lines should not diverge from each other in the least.

Step 5: These Lines Are Parallel

A close examination of the lines drawn reveals they are parallel. The square is not out of square.

But, earlier I said this square was not square when it was new. I made it square.

Step 6: A Suggested Way to Square a Square

I have never tried this method, but it is a recommended way to make a square square. Use a small punch to make dimples that force the legs of the square more open or more closed. Making a dimple where the punch is in the photo would tend to close the legs of the square slightly. Placing the punch nearer to the inside corner would tend to open the legs of the square. This could work with a flat metal square as pictured here. It would be difficult to utilize with the square in the previous photos.

Step 7: My Preferred Method

My preferred method for squaring a square involves using a file. Assume the legs of this square are open too far. The angle between the two legs is greater than 90 degrees. Make a file stroke as shown by the red line. Make another as shown by the yellow line. Make a third as shown by the green line. Make a fourth as shown by the blue line. Make yet another as shown by the azure line. Check the square for squareness often. Repeat the filing pattern until the square is truly square.



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    I use something like this to check a spirit level , first align it to level on the side of a wall and draw a line along the top side, then reverse the level and check if it aligns with theline

    A little basic physics or geometry and some calm thinking are as good as or better than expensive equipment any day.

    You might want to point out that this only corrects the top (outside) edge of the square. The inside angle still won't be square. I like the parallel line trick though.

    You are very much correct. Thank you. The inside of the leg would still be in error, assuming it was parallel to the outside edge in the beginning.

    I am a professional carpenter, and I often "tune" my framing square using the parallel line method to check it, often off of the side of table saw table. I then tap gently on the inside or outside of the heel of the square using a smooth faced hammer.

    Thanks for your comment. I had never actually heard from someone who uses a hammer on the heel of the square. What would you say causes your square to go out of alignment?

    The tapping part is just as you described, but without the punch. Although I try to keep it out of the hands of my helpers and crew, it sometimes gets dropped or otherwise abused or gets in a bind in my toolbox. Another possible cause is that I often use a marking knife rather than a pencil, particularly when laying out stair carriages, which may cause excessive wear on the blade and tongue, but I think this effect is minimal.

    The kind of bumps to your square that you describe are very understandable in your situation. I have a framing square that rests against a wall a lot and has not been dropped in a very long time, if ever. I have not had to realign it since I first tweaked it shortly after I got it. I may be a babe in the woods for naivete', but I always assumed a square off the rack from a store would be square. I have since learned that is not a good assumption to make.

    The first rule of carpentry is that wood always moves and there is no way to stop it. The second rule is never to assume that anything is square, level, or plumb. This goes for houses and tools fresh out of the box.

    Ah, yes. Lesson #3 of working with a construction crew. Lesson #1 was how to push a broom and Lesson #2 was how to carry lumber.