"How Square Is Square" was prompted by my getting a clever little gadget from Lee Valley. It is called "TapeTip" and it can be attached to any steel tape measure. The visual to the right is from Lee Valley's website and the URL is listed below. It is the first $4.95 gizmo that has had instant success in my shop.

   *to the TapeTip page at Lee Valley

    Here, Andrea has attached the TapeTip to her measuring tape and is taking the corner-to-corner measurements that will tell her if her cabinet is square or not. It is the age old way that out performs the squares that we use — more about this in a second.

   Of course, if one measurement is a tad longer than the other, you place a clamp across that direction and pull the measurement so that the two are equal. That is what the pros do, but I have a problem with that. Basically, I don't like the idea that at the final step, you make adjustments of this sort. It shouts that the earlier cuts and assemblies were not done properly — and that is what I want to address for the rest of this page.

  Andrea's finest hour — posing with squares. Actually, I have purchased more than my fair share of squares. The one Andrea is holding is from Enco Co. — it is 18" and cost $60 and is very accurate. It is also heavy. I use it primarily to test other squares.

   This 16" draftsman triangle  can serve as a square as well and it only costs about $15 and is available everywhere.

      This "speed square" is available at home centers and hardware stores everywhere. While it may be viewed as being a builder's tool, I find that it is very useful and plenty accurate.  When I am shopping for one, I take my heavy engineer's square to the store with me. I try each square until I find one that is square against my large engineer's square.

     Rafter squares seem to be a better squaring tool because of their size but watch out, they can be out of square. They are convenient to use though so if you do get one, just be sure to get a square one at the store and then keep it square (dropping it on the floor is not a good way to maintain its accuracy.) There are ways to correct an out of square framing square but at that point, I chuck it and get another one. Square is too important to me.

   Which brings me to my favorite shop square. It is made by Incra and it is accurate, solid and easy to use where it counts.  

     Square doesn't just happen. It takes the panel that is cut square, with an edge that is square, with a Domino tenon which is cut square — you get the idea.
   It is like the mathematical theorem that the "whole is equal to the sum of its parts." The cabinet will be square overall, if each and every piece is square. So while it is nice to think that you can put a clamp from corner-to-corner and pull everything into square, the only real way is to have every piece square.

 (updated June 9, 2007) A reader suggested that the 1281 square from Woodpeckers should be on my favorite square list, so I got one — two actually. That tiny one on the corner of the board is a separate product that we just mounted with its big brother.  The accuracy of the large square is better than .001” over the entire 8” X 12” size according to the manufacturer. Woodpeckers offers a "...Lifetime Guarantee to stay square to within a minimum of .001 or ”...we'll replace it." Sounds good to me. The square comes with an attractive mounting board which will help keep it from getting banged around. (Click here to go to Woodpeckers page.)

Here are the two squares. The larger one is  8" X 12" and the small one is about 1" x 2". Is the small one too small to be useful?

   This small square is the right size for checking the square of a freshly cut piece of wood. It just fits better and leaves your hands free to hold the wood comfortably.  The hard task is to not lose it in the shop.  The storage display that is now mounted on the back board will help to keep it handy — if I remember to put it back. Elena and Andrea are both good at that — picking up after me.

      I would be remiss if I didn't describe how to check for square. This can be done to check any of these square devices.  It also can and should be done to check for fence and guide rail set-up.
   First Elena carefully lines up the triangle or square so that the top is flat and aligned with the top of the board. She then runs a marker down the length of the triangle.
 

   Next, she flips the triangle or square over and draws another line.

   If the lines do not coincide, like the red ones here (exaggerated for the sake of illustration), then the device is out of square. Elena actually had both lines exactly on top of each other, so the triangle is square.

   With the knowledge that the draftsman's triangle is square, she can use it to square the fence and/or the guide rail.