Twisted Frame

[Don Lamothe]

I’m making a display case for my grandson. The sides are basically a frame with mortise and tenon joints. I put the first side together and before I glued it up I laid it flat on my work bench and it wasn’t… flat. It’s got a bit of a twist to it. Is there a secret to getting this thing flat before/during glue up?

Thank you!!!

[Kevin Jenness]

If the parts are true and the joints cut square and tight the assembly should be flat, if not, consider all the points in order. Try assembling each joint in turn and testing with a square and straightedge to see where the problem lies. If the entire side is put together and clamped flat you may see gaps in the joints that can be improved by planing. If a stile or rail is badly twisted you will likely have to replace it.

[glenn bradley]

Kevin's got it. Your material needs to be consistent in thickness, width, and mitered accurately. I know it sounds obvious but many folks try to make square assemblies without starting with square stock. It is really just that simple.

[John TenEyck]

Kevin's got it. Your material needs to be consistent in thickness, width, and mitered accurately. I know it sounds obvious but many folks try to make square assemblies without starting with square stock. It is really just that simple.

And that difficult. If the edges are off only by a degree or two the frame won't be flat. If the mortises aren't cut perfectly parallel with the faces, same thing. If the shoulders of the tenons aren't perfectly in line, same thing. There are lots of ways to fail at what seems like a simple task. So, yes, you need to check your stock for straight, flat, and square before beginning to mill the joinery. After that, cutting the mortises perfectly parallel with the faces is critical. I've settled on a horizontal router mortiser to cut my mortises as the face of the part is clamped flat to the table, guaranteeing the mortise will be parallel with it. And I use loose tenons 95% of the time, because that allows me to cut the rails to final length on my RAS with no concern about tenon shoulders. I like simple.

John

[Bradley Gray]

Sometimes it's best to burn the evidence and start over.

[Ron Selzer]

Sometimes it's best to burn the evidence and start over.

So very true!!
Ron

[Cameron Wood]

Dry fit and clamp the whole thing- it may be OK.

Glue the whole frame at once as well, standing on a flat surface.

For a flat frame, sometimes shimming it to an opposing twist during glue up will work.

[andy bessette]

...Is there a secret to getting this thing flat before/during glue up?...

It's no secret. Mill everything flat and square. Then do a dry-fit, prior to gluing, on a flat assembly table. Make certain it is flat and square before gluing. If not, find where you messed up and start over.

[Rod Sheridan]

Sometimes it's best to burn the evidence and start over.

Agreed, that’s my plan as well, regards, Rod

[Tom Bender]

Sometimes lightweight panels are held straight by the rest of the piece. The sides of a display case might be good candidates.

[James Jayko]

On the highly obvious side, use just enough clamping pressure to close the joint...you don't have to squeeze the life out of it (and a twist INTO it...)