Thread: Getting my Hammer c3-31 fence square

Do one cut then rotate the piece so the fresh cut edge is against the fence, do this four times until all four sides are cut. Then cut a strip off and measure the thickness, any error will be magnified 4 times, so gives you a very accurate measure of squareness.

Cheers Andrew

Cut it 3 times and measure the diagonals.

The simplist method in 3 cuts

Thanks guys, River have a look at the video in Chris’s reply. In it he says that your method comes up short because a trapezoid can have equal diagonals but will be out of square.

Yes, but if you do the first two cuts from the same edge against the fence, it cancels that theory out. Generally I’ll do two cuts from the same edge against the fence, then measure from one of these cuts across to the other, at the top and at the bottom of the board, parallel to the fence edge, and if the measurement is the same, the saw is square, or very close. Then put one of those edges against the fence snd cut the final side, then measure diagonals.

It works for me, same as it worked for the old man for 60 years.

Doing it as shown in the video has got one big advantage, it takes the guesswork out of how much to move the stop. When the first cuts are complete and the board measured the stop can be moved or packed a given amount and the change measured when the second lot of cuts are done. Using the movement or packing used as a known measurement it is pretty simple to work out how much the stop has to be adjusted for a perfect result without guess work. I have found I can do a perfect adjustment with a single adjustment most times using an accurate tape or rule. I also have an accurately made measuring rod which is used to set all fences in my workshop so they all cut the same. Fences are like tapes, not every fence cuts to the same measure if a single measuring standard is not used to set them all.