How do I take a piece of plywood that is not square and make it square? I'm new at woodworking.

The sides are not straight which I can tell by just looking at them How do I cut the wood to make it straight when both sides are not straight cuts?

  • 2
    Welcome to WSE. What tools do you have for cutting the wood? – Ashlar Mar 13 '18 at 3:56
  • OP we need to hear back from you as the suitable responses depend entirely on the tools you'll be using — it requires completely different methods if using a circular saw or jigsaw, table saw or doing this with hand tools. – Graphus Mar 14 '18 at 14:04

I've used this method before to straighten boards. You make a jig like the one shown. The jig is used as a reference point to straighten the uneven board.

enter image description here


Assuming you have a saw, You will need to mark a straight line along one of the edges. ( I understand you to say that all edges are not straight) Cut that line, you now have one straight edge. Construct a 3-4-5 triangle off of the straight line.

3-4-5 Triangle - It doesn't matter what units you use it is a matter of proportion. Say the line you just cut is 4 feet long, Measure perpendicular from that line at one end 3 ft. From the other end of the 4 foot edge measure to the end of your 3 foot "line" Adjust the end of your 3 foot line until the measured length is 5 feet. At this point the angle between the 4 foot line and the 3 foot line is 90 degrees. This is easier with 2 tape measures

Mark this line and cut. You now have two straight lines that are square to each other. The other sides can be marked by measuring off of the opposing side to construct a parallel line.


Usually what I do is I pick a side to use as a base line, and I start measuring and cutting from that reference.

If, for example, I'm cutting a square I will draw a 90 degree line using the one side as the reference. I then cut that, which would leave me with two sides that are square to each other. I would then repeat the process for the side directly across from my first reference point, using the side I've just cut as a base of reference.

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