squaring trick aka the 6,8,10 rule

[macka]

If you don't have a square, here is a neat trick I learnt today. measure 6 inches on the inside of the bottom rail from where the rails join, and mark a line. Then measure 8 inches on the inside of the "perpendicular" rail from the base rail. Put your tape or ruler on the six inch mark, and measure up in a direct line to the 8 inch mark. It should measure 10 inches if you are square.

[Gerald_G]

Good old Pythagorean theorem - see math class did have an application.
(son of a math professor)

http://en.wikipedia.org/wiki/Pythagorean_theorem

[jimFPU]

Yes, the Pythagorean Theorem, better known as the "3,4,5 Rule." (http://www.cut-the-knot.org/pythagoras/index.shtml)

AKA: a² + b² = c²

Teachers were right...again.

[Sparky]

another thing to keep stuff square- measure corner to corner. if there are 4 corners, that is.....

you can also put 2 strings on there to see if they cross in the center.

:D

[TheKid]

I believe this was discussed before. 3,4,5; 6,8,10; etc. If you're building a garage, deck, or an addition to your house etc., 12,16,20 comes in real handy for squaring the foundation footing.

[Trailblazzzzzer]

A fast way to check square on a foundation frame is to measure from both oposite corners (across the center). When both measurements are equal the rectangle/square is Square.

[TheKid]

Quite true. For starting and laying out lines, we always used a variation of the 3-4-5 method for getting the footings square. Once the corners were were established, diagonal measurements were taken. Sometimes we got lucky and found a guy with a transit, which saved a lot of time. For larger structures (like a 2400 sq. ft. ranch) we always hired a company to build the foundation. It was too much to do by hand.

[lumo]

good old books can help you too... as they have 90° angles too ;)