I have a giant size paper which is close to a square. Each side is about 155 cm (61 in); some are a bit longer and some are a bit shorter and not all the angles have exactly 90°. I want to cut it into a perfect square. I'm willing to reduce it to 150 x 150 cm (59 1/16 x 59 1/16 in) in order to get the square. How do I do this?
I've heard that the best way to cut a perfect square is to have a mold to trace the square but I don't have a giant size square mold. I do have a meter stick, measuring tape, a couple of set squares, and a protractor, besides an Envelopener for cutting the paper. In theory it would be easy to cut it to the right shape and size but I spent a whole morning trying to do so and failed! It's just really hard when the sheet is that big .
Last edited by Gerardo on October 22nd, 2015, 2:31 am, edited 1 time in total.
I'm not 100% sure this will work, but here's what I would try:
First, you'd need to draw a straight line roughly parallel to one side of the sheet and also close to the middle. (It might help to get a longer straightedge, but I've never seen one longer than about 120cm.) Then use the protractor to measure out a right angle close to the middle of the line you just drew.
From there, mark the midpoint of each arm of the cross and draw more perpendicular lines.
You might need a couple meter sticks, but you'll have to make a grid of smaller squares in order to make one larger one.
One other technique--if you don't mind a few creases--is to crease the sheet roughly in half, using the meter stick as a guide to keep the crease straight. Then, crease perpendicular to that, also roughly halfway between the edges. This will give you something close to a 75cm square, which should be manageable.
Then fold one folded edge to the other (along the angle bisector from the center of the sheet). This will give you a right isosceles triangle. Finally, make a cut through all the layers at once (if possible) to perfect the triangle and unfold your square.
Also, at that size, getting it exact isn't entirely necessary. Even a millimeter of error is fine with a 35cm square, and that would translate to about half a centimeter for the size you're working with.
They work much the same as rulers for the purpose of keeping things straight (hence the name). The main advantage is that they're easier to find in larger sizes, at least as far as I know.
I'd fold a diagonal. Leave it folded and fold the other diagonal making sure the folded edge lies exactly over itself. Unfold completely and measure the same length from the middle outwards along the fold lines. For a 150x150cm square the diagonal should be about 210cm long, so half of that would be 105cm. So it would be 105cm that you would have to measure from the middle outwards along the diagonal fold lines. Biggest problem now is to get a straight line between those marks. Maybe you can find a table or cupboard or mirror or picture frame or anything else with a long enough straight edge to fold the paper over or you try your luck pinching the points and making a straight crease between those points. Then with a ruler and a sharp knife cut the square along the lines.
I got a 50 cm set square. It was really helpful. I used it to start measuring 90° angles between 150 cm from the shortest side. I cut the extra paper. That was how I started. The whole process was pretty simple but really time consuming, it took me around two hours to finish.
At the end there was only a difference of one or two mm between each side .
.
.