"Check diagonals for square"

[Jim Crockett]

Since I began reading woodworking books and viewing online projects, the plans all say to "check diagonals to verify squareness". But not once, in all the things I have read, has anyone ever said what to do if the diagonal measurements are not equal.

What brought this to mind is that I am in the process of making a table/stand for my benchtop drill press. I was measuring the diagonals and they were 1/16" off - no big deal since it is a piece of shop "furniture" and it is already glued and screwed.

Comments anyone?

Jim Crockett

[Dave Anderson NH]

The short answer is to run clamps from corner to corner on the longer dimension. How you do the clamping is dependent on what kind of piece you are doing and what types of clamps you have available.

[Jim Myers]

Wood magazine just ran an article about this. I think it was one of the last two issues.

I don't have it in front of me but it explained how to check for square and how to adjust.

Good read if you can find the copy. The main article on the front was "Get square and stay there" or something simmilar.

[David DeCristoforo]

"But not once, in all the things I have read, has anyone ever said what to do if the diagonal measurements are not equal."

The remedy will vary based on what you are attempting to square up and how it's constructed. A solid wood table top for example would have to be trimmed in some way. A drawer box may be out of square because the bottom panel is out. An out of square cabinet carcase may be remedied by adjusting the back panel.

"...the diagonals and they were 1/16" off..."

Keep in mind that the difference in diagonal measurements is double the amount of "out of squareness" (?) So your difference of 1/16" means that your project is only out by 1/32". Not, as you mention, a big deal.

[Jim Crockett]

Thanks, everyone. The info you all provided is very useful and I'll have to see if I can find the pertinent issue of Wood Mag.

JimC

[Andrew Williams]

Lots of times you can just squeeze it a bit with your arms and that will put it back square.

[John Lucas]

First, 1/16" is very little a "discrepancy." I think you did well to have it that small. To remedy, at glue up time, put a clamp across the long corner-to-corner dimension and tighten it until the dimensions are equal. Let the piece dry totally (overnight). There may be some spring back but usually the assembly will stay at your corrected measurements.

[Nissim Avrahami]

I know a different method, like in the pic below.

When you move the clamps out of parallel or square the clamps want to find the shortest line and they move all the structure till they get again square or parallel.

niki
68481

[Cliff Rohrabacher]

I know a different method, like in the pic below.

When you move the clamps out of parallel or square the clamps want to find the shortest line and they move all the structure till they get again square or parallel.

niki
68481

Which of course also provides clamping for the structure's joints - a good thing~!!

This (old school) method takes a bit of finesse to get right. But once set it's golden.

[David Giles]

Sometimes the wood hasn't been cut square. Look at Niki's picture and imagine the crosscuts slightly out of square. Or a drawer box where the blade isn't exactly vertical. Looser clamps can help square things up. Then tune up the machine.