Help with flat panel glueup's

Re: Help with flat panel glueup's

Pam Niedermayer - Austin, TX

>After panel frame gluing, you're pretty much done with any sort of panel adjustment, the theory being that that grooves into which the panel is glued hold the panel within some sort of movement range. I suppose you could sand it to death. Or you could pack the grooves if they're too big.

Pam

Re: Help with flat panel glueup's

Stephen in Ottawa

>Sorry, I wasn't referring to a frame-and-panel. These are just panels dovetailed to make a carcass.

It might not be a problem...

Scott Burr in Ben Lomond CA

>1/32-1/16" cup over a panel that size is not a lot to deal with IMHO.

The cup will probably be flattened out when it is glued and clamped good. DT assembly can remove some cup in panels in just the way they go together. This also depends on which way the panels are cupped...

Will you have dust panels in this carcase?

Pam Niedermayer - Austin, TX

>

I'm a bit puzzled

bill tindal, E.TN

>There was a bit of distraction before you got to the question and I may have gotten lost along the way. I am understanding that the "problem" is the whole panel is bowed a bit? The problem is not that the joints didn't align perfect?

Large panels are not going to stay perfectly flat unless they are constrained to remain flat. What ever holds the sides together should hold these sides sufficiently flat for most people's needs. There are of course exceptions. If your lumber was not stable it may have bowed too much to be easily made flat by assembly, but I presume this is not the case.

You have discovered why I will never hand plane panels. They have to be flat to plane, flatter than they need to be for the actual construction. I glue them up and run them through a planer which mashes any bow flat and cleans up the joints. I rely on the framing to hold panels and tops sufficiently flat for the piece to function. Well, and I don't like planing, especially the aggravation of tear out, or when the plane refuses to cut a low spot which may only be 0.005 low.

Re: Help with flat panel glueup's

mikew

>Hi Stephen,

Carcasses held together with DTs are pretty forgiving and most of the cupping it *sounds* like you have will be fairly straightened out by assembly.

The real trick is in marking a cupped board to another. I have gone so far as to clamp cauls across a cupped board to flatten it enough if I thought transfering marks was going to be an issue. I have also lightly dampened the concave face and laid it down on a flat surface with that face down, weighted the panels using stickers for air circulation on the top surface and had the panels uncup long enough to join them. The picture below had the side cupped a bit. Once joined, it has held straight.

Now if I can only get back to that project...

Take care, Mike

Re: Help with flat panel glueup's

George@Colonel's Workshop-Havertown PA

>Good Afternoon Stephen,

The above advice regarding the use of cawls is sound. They work well to keep the joints tight and the panels flat during glue-up. When constructing my wife's cedar chest, I used box joints. When the glue cured, there was no bow or cup visable. Yours sound minimal anyway. I doubt you'll have a problem, but I suggest you dry fit the assembly together with cawls applied and examine the unit.

George

Re: Help with flat panel glueup's

Stephen in Ottawa

>Thanks George and others.

What type of wood would be suitable for the cauls, and roughly what thickness would you make them for the panel sizes that I've described ?

- Stephen

Cauls and Al bar clamps

bill tindal, E.TN

>Cauls are unnecessary if you have stiff clamps. If your panels are not bowing in the clamps, don't bother. I never use them for panels and I have glued hundreds of panels.

Pipe clamps are prone to bow which is why I don't recommend them. I don't get any bowing with the aluminum bar clamps such as can be had at Woodcraft (these are my favorite because of the thumbscrew). Also sturdy steel bar clamps don't bow either, but they are heavy and glue sticks to them.

BTW, the I know the person that makes the clamps sold at Woodcraft. He tells me they are used in some furniture factories and that they are so strong that the people tighten them with air torque wrenches. I find them strong. They can be shipped wholesale from factory in lots of 10.