Glued cabnet doors warped

[Brian Runau]

Howdy. Just finished my first set of tounge & groove shaker style panel doors for my first nice cabinet. I have a dead flat table I built for assembly but the doors came out warped after my glue up. Could I have caused this by over tightening my clamps?

Thanks.

Brian

[David Hawxhurst]

short answer is yes. i have had the same problem even using so called parallel clamps. alternating the clamps may resolve this warping problem. currently i use a clamping table with cauls to keep thing flat. the clamping table works very well for me.

[Kent A Bathurst]

Yep.

Cauls are a must. I also alternate my clamps up-down-up-down between the cauls, and even go so far as to alternate the handles - towards me-away-towards-away. That last bit is most likely a bit over-the-top, but IMO the cauls and the alternating up-down is critical to successful flat glue-ups for all types of panels.

[J.R. Rutter]

You guys are using cauls for door glue-up, or just for panels?

Brian - did you use a solid wood panel, or plywood? If the rails and stiles are not done moving yet (in terms of moisture content) then the door can certainly warp as it finishes acclimating. I suppose that clamps could play a part in it, but without details on exactly what happened to the doors - shape change - it is hard to say if clamping caused it.

[scott vroom]

I use cauls for panel glue ups and 5 piece door glue ups. For doors up to 36" I typically use cauls on the ends only. I also alternate clamps up-down-up etc.....I use pony pipe clamps and they tend to curve the glue up if I don't use cauls.

[Sam Murdoch]

As David says - short answer is yes. Even with all care taken to use flat stock and floating panels, too much clamp pressure will certainly cause some problems. My door and panel assemblies are glued up using some K Body Bessey clamps - typically without cauls. I stand the panels/doors on edge with a clamp at each end (sometime 2 clamps depending on the rail size) and set them aside on the floor to dry leaving my table open for the next glue up. An ESSENTIAL step before moving on to the next glue up is to check with a straight edge to make certain that I have not warped the assembly. If so, I loosen the clamp, move things around a bit and retighten. Sometimes though I have no choice but to clamp a pair of opposing cauls. That is the exception though. Point is that clamp pressure can cause warping.

And if I use 2 clamps at each end I place one on the front and one on the back to even the pressure. Always a good idea to alternate the clamps if you can.

[David Hawxhurst]

mostly only for panels now. there was a learning curve involved with making flat doors. took me a few times to figure out the alternating clamps and clamping pressure could cause doors to warp. plano clamps (panel max by peachtree seem to be the same) would be something nice for doors and panels, just don't feel like spending the money for them.

[Clint Olver]

What kind of clamps are you using? When I used to use pipe clamps, I'd check flatness with a straight-edge the shim them to get my panels flat. Once I bought the GS parallel clamps, I didn't have to shim anymore, flat glue-ups every time.

[Steve Griffin]

Careful use of single pipe clamps for me.

Keep in mind there are other causes of warped doors than your glueup.

-Out of square edges on a groove piece
-Uneven shoulders on the tongue
-Warped stile or rail pieces.

Building flat doors is one the challenges of cabinetry, and even if you do everything right you sometimes get a warped door because of wood movement after assembly. If a door doesn't meet your standards, just make another.

[Tom Fischer]

Yes, easy on the clamping pressure. Not much needed. Just for fun, put some titebond on two flat surfaces, rub them together, NO clamps. Check the strength of the joint next day. Titebond is amazing stuff.

Also, when you joint your edges, make sure to alternate. First edge goes against the fence, next edge opposite side of the fence. In this way, even if your fence is slightly off (e.g. 89.5 degrees), the opposing board will go in the glue up at 90.5 degrees.

[Carl Beckett]

As David says - short answer is yes. Even with all care taken to use flat stock and floating panels, too much clamp pressure will certainly cause some problems. My door and panel assemblies are glued up using some K Body Bessey clamps - typically without cauls. I stand the panels/doors on edge with a clamp at each end (sometime 2 clamps depending on the rail size) and set them aside on the floor to dry leaving my table open for the next glue up. An ESSENTIAL step before moving on to the next glue up is to check with a straight edge to make certain that I have not warped the assembly. If so, I loosen the clamp, move things around a bit and retighten. Sometimes though I have no choice but to clamp a pair of opposing cauls. That is the exception though. Point is that clamp pressure can cause warping.

And if I use 2 clamps at each end I place one on the front and one on the back to even the pressure. Always a good idea to alternate the clamps if you can.

Echoes my experiences/method exactly.

[Kent A Bathurst]

I use pipe clamps 80% of the time, overall. Essentially 100% of the time for panel glue-ups. Ya gotta alternate pipe clamps. No option, IMO. They can turn out one hellacious amount of pressure, and the pipe itself flexes - those forces are counteracted by the up-down-up-down scheme, and the cauls.

I subscribe to the "ain't no way to starve a joint in a home shop" philosophy. so I am happy to reef on them. but - I jam-pack the surface with cauls as well. I get virtually dead-flat glue-ups every time.

For frame-and panel stuff - it depends:

If I am doing, say, cabinet doors, then I always use cauls to keep the stile-rail joints flat, and this really helps me on the opposite-corner flatness/warp issue as well.

But, when I have done, say, a frame and panel blanket chest, I will often glue up one free-standing panel at a time, but it is sitting in the entire piece with the other parts dry-fit. This not only lets me keep it flat, square, and plumb with respect to the rest of the case, but this approach also ensures that everything goes together just ducky in the final assembly step.

My strong suspicion is that my methods are ones I came up with in my self-taught stumbles as I mistaked my way up the learning curve over the years. Other guys obviously have other techniques that work perfectly well for them. But for me, it has become basically like the muscle memory you develop with a handsaw - it is simply a routine habit, and I don't even use much thought as I do it anymore.

One last point - I think it is critical to stand finisued glue-ups on their edge/end as soon as they come off the cauls/clamps. Stickering is another option. Never - never - lay them on a flat surface. I have been astonished at how quickly a panel will distort when laid flat on, say, the TS table. Nothing ruins your day faster than a nice, flat panel that warped.

[Jeff Duncan]

If you have any parts left over try clamping them up on your table and checking with winding sticks to see if they're staying flat. As mentioned there are plenty of reasons a door can come out non-flat so hard to say without more info. Just out of curiosity....how did you check your assembly table for flat?

I agree with a lot of what Sam has already said....as far as clamping the short answer is yes you can distort a frame by over clamping. You need enough force to bring the joints tight and that's it. I also like parallel clamps b/c they're easy to get doors glued up flat quickly. Pipe and I-beam style clams exert a LOT of pressure much more easily than parallel clamps so you can overdo it easily. I don't bother with cauls for cabinet doors. With parts machined properly and a flat surface to glue on they're not necessary.

good luck,
JeffD

[Patrick Galpin]

Brian, I use the LV Veritas Panel Clamp, never have a problem with over tightening as the tighter you clamp the straighter your boards/ doors / panels will be, it's an amazing system and foolproof, which is what I need most of the time. http://www.leevalley.com/en/wood/page.aspx?p=31181&cat=1,43838

[William C Rogers]

Brian

Over clamping is the most likely the main cause for warping. I have had the same problems. I have not tried some of the suggestions mentioned or use cauls. I always start with 13/16 stock to make the rails and stiles. I glue up and use parallel clamps and tighten until joints are tight. I then check with a straight edge, and if ok (within 1/64 of flat) and both front and back are tight, I am done. If not, I loosen and move to flatten and then snug up clamps again and recheck. I also check for squareness. I have never been good enough to clamp perfectly flat or get the rail and stiles to be perfectly even. Which is not good enough to use. So I ended buying a drum sander to fix my lack of perfection. I start with 120 grit and when everything is perfectly flat I change to 220 to make the final ROS easier. I end up with flat doors about .765 thick almost every time. A drum sander is a big investment, but for my not so perfect it is the best way for me to succeed easily. And definitely keep in mind Steve's other suggestions especially about out of square rails. I have gotten into a habit of checking each piece of stock before routing and and have found time to time something happened and would be out of square. A drum sander won't fix squareness of course.

Bill