Measuring squareness, use square math? Learn the 3 methods here, it's another self reliance skill to own

  Two of my grandson's have been here helping me out for the past few weeks, I'd like to say I can keep up with them, I can't. They are working on my old boat for the past few days, I painted it a few years ago and it's due for another coat, they have been chipping, sanding and cleaning for 3 partial days, it's looking good. I have 10, ranges in age from 8 to 21, they grow fast. When they are with me, most of them come during their various days off of school, the ones that don't work or go to school just come and go. I like to work with them on projects and I believe they like to work with me as well, I teach them lot's of stuff. They have helped me build a new front "stoop" from wood, Raised bed garden boxes

The grandson's can accomplish anything I swear.

were built by one of them as was my big composting worm farm in the yard. We repair things and build things, they learn to use a table saw, miter saw, routers and all sorts of hand tools. I have taught them to read measuring tapes and rulers, how to mix and use epoxy glue and to their disapproval how to weed. Which brings me to the subject of this blog, squareness, how to check assemblies for being square. There are a lot of different ways to check square, I will cover three: 1) 3-4-5 method of squaring, 2) Cross squaring 3) squaring with a square, all effective all very good to know time saving methods.
   1) 3-4-5 square method, "squaring up" an assembly is essential for the objects strength and appearance. It is most important in multi-story buildings, the sky rises that I worked on (I spent 20 years as a structural steel iron-worker, we built Diablo Canyon Nuclear facility, and the Moscone center in San Francisco). On all of the structures the engineer's dictated a tolerance of 1/4" +/-, that's actually a lot. In the event a vertical column of 20 feet used the 1/4" tolerance on each foot the top would be off 5", it doesn't take much for a vertical column after 5 stories high to be off a foot or more. Squaring assembly's is absolutely needed to be completed on each and every assembly prior to erection.

Routine when once you begin to use the 3-4-5 method of squaring. 

3-4-5 method, used on an assembly with at least two legs, it works on forms with an open side or end as well as with one vertical member and one horizontal member. Squaring is done prior to final welding or nailing depending on the structure, all the parts are cut to size and either tacked together or held together with one fastener on each corner. The part is laid out on a table or "saw horses", larger ones laid out and assembled on the floor or deck. When the assembly is temporarily tacked together and appears to be square this is the time to check it. Choose one corner of the frame, I normally start on one end the right hand corner. With a small square strike a line 1 inch from the edge of the part, then mark the center of of that line and draw a circle around it. From that mark measure down the left leg 3 feet, mark it, draw a line with a square across the part and mark the center line, circle it. Go back to the original point and measure 4 feet down the right hand part, again draw a line across and mark the center line, circle it. Now grab your assistant (in my case assistant's) have one stand at the 3 foot mark and the other (or we can do it ourselves) person by the 4 foot mark. One person sets the measuring tape zero mark on the circled center point, Now measure the point between the 3 foot and 4 foot mark, if your assembly is square it will read 5 feet. If it reads any other measure the frame must be adjusted, it will take two or three moves to figure out which way and how much to move which leg. The final task is to install 4 more fasteners in each corner or if welding heavy tacks prior to final assembly. When it is assembled, re-check the 3-4-5 square, if it measures correctly you're golden. Squareness can be checked as well with the following method of measuring squareness.

Cross squaring, not always this distance, but it is very common.

  2) Cross Squaring, after assembling a large component and it is laying flat on saw horses or the floor, measuring squareness needs to be accomplished. For example if you have just assembled a 40 foot x 20 foot form and you are ready to pour concrete, get your partner and grab a 100 foot measuring tape. With a small square mark each corner, measure from the end 1" ("burning an inch") then mark each at the center. With one person on one end and another on the far end measure from the right hand mark on one end to the left hand mark of the far end, write the number down. Then proceed to the other sides and measure in the same manner, they should be fairly close, many lunch bets have been lost from over confidence. If the measurements match you are finished, complete the final assembly and measure once again. If they do not match the assembly must be squared, pushing, shoving, prying and use of motorized equipment are several ways to move a heavy object. Generally if the measurements are within +/- 1/4" it is a good measurement and can be completed. After the unit is completed and squared, the last method of measuring squareness may be used in the corners as a last check. Need a freshening up on a measure tape, check this link out here.
  3) Square Math, measuring squareness with a two foot square, one of the most versatile tools in your tool kit, carpenters and iron-workers normally keep two by their side. The "two foot square" is 1 1/2 foot on one leg and 2 foot on the other, it can be used for squaring assemblies, setting angles in degrees, laying out steps for stairways, as well as use a a straight edge. To check the squareness of the square (yes it must be done), begin by placing the square's 1-1/2 foot leg (lay it to the left) even with the edge of a piece of plywood or steel at least 2 feet wide, the flat squaring piece should be a minimum of 1-1/2 foot x 2 foot. Push the 1-1/2 foot inner edge against the outer edge of the plywood and strike a line down the 2 foot edge. Flip the square over so the 1-1/2 foot leg is now laying to your right and the inside at the 90 is even with the line you struck and strike another line. If they line up you are fine, if not the square must be squared by peening the inside or outside, inside if the square is open, outside if the square is closed. To check the square of an assembly simply go to each corner and place the outside of the square in the inside of the assembly, after the 3-4-5 method and cross squaring it will be square.  Learn more about the 2 foot square here.

A few functions of the 2 foot square, or commonly called "framing
square". 

  It's also recommended that if a person is using more than one measuring tape, or is working with more than themselves, all measuring tapes should be the same brand. The tapes need to be compared to be certain that all of the inch, fraction and foot marks match, they can be off a considerable amount depending on how many different brands there are.
  I think this is a very boring subject, however it is one that some people just are not familiar with the many methods to square concrete forms, or ascertaining square footage. I use them all the time when we are building things the foundation for my shed, the deck or building a trailer. One of the three handiest tools the other two are a good tape measure and the use of PI (3.14) it's geometry Watson.
  I hope this blog has enlightened you a bit, maybe you knew two methods, or one, or all three regardless it's essential to "stay square" to ensure a professional looking assembly. Structures gain a lot of strength when they are held vertical, gravity is in this case our friend and ally when everything is square but is a destructive force when it is out of square. (I'm kind of thinking of the Millennium building in San Francisco, leaning over slowly). In our desire to be as "self reliant as we can possibly be", in the event we must build a temporary structure or any thing vertical, if it is square it will have a better chance of staying vertical.
  Thanks for reading, leave a comment or suggestion. What are you building?

jacquesandkate  emergencykitsplus.com