Replies

1. 
   dstevick | Dec 23, 2006 08:23pm | #1

   Masrol,

   My guess is something changed in the wood's environment from the time you glued them to when they cupped. Either the wood increased or decreased in moisture content. Since I don't know the specifics of your shop situation this is just a guess.

   In any event the solution for future glue-ups is to: make sure you alternate the growth rings so changes in moisture content don't cause cupping in the same direction; make sure you acclimate the wood to your shop environment for a few weeks; and try to keep the shop environment consistent from the time you start the doors to the time you finish. You might even want to invest in a moisture meter.

   For the doors you already have you can cut them apart along the glue lines, re-joint them, glue them back with the growth rings alternating, and add fillers on the ends to get back to your desired width.

   Good Luck

   Dean

1. 
   Masrol | Dec 23, 2006 08:59pm | #3

   I supposed you're right. I stored my board at the ground level. My poor working area (for gluing work) is at the second level, which is very very hot during daytime. Possibly temperature change has to do with it.

    I had built some frame & panel doors from the same stock before. From cutting to gluing, assembling  and finishing  were done at the ground level (floor). I never experienced cupping problem. But when this working space became so congested, I started do gluing work at the second level ( not a properly ventilated  second level - exactly the void area between the roof and the ceiling).

   Thank you very much.

   Masrol     

1. 
   edmund | Dec 27, 2006 07:03am | #13

   could your panels have been left lying flat one on top of the other, that would do it

2. 
   ptu | Dec 23, 2006 08:27pm | #2

   Sounds to me like your wood wasn't dry when you built them??? I don't have a quick solotion, except planing them flat after you are sure they are dry. I don't think clamping them down now will flatten them.

3. 
   HowardAcheson | Dec 23, 2006 10:06pm | #4

   How did you store the panels after you removed the clamps? Were they stored flat against another surface? Newly glued up panels must be stored so that air can freely circulate equally to both sides or you will end up with uneven moisture contend on each side and warping is the result.

   You may be able to stack them with stickers between the panels and weighted on top and they may flatten.

   Howie.........
1. 
   BarryO | Dec 25, 2006 11:01pm | #10

   Newly glued up panels must be stored so that air can freely circulate equally to both sides or you will end up with uneven moisture contend on each side and warping is the result.

   Yep.  'true for any newly-machined wood, especially if the humidity in the shop changes.

4. 
   philip | Dec 23, 2006 10:28pm | #5

   Mas, don't panic. Howie gave it to you straight-try what he has said first -give it a few days. You could help it a bit by wetting the concave side, or get a bit more radical by setting that side against something damp .
   I am quite sure that the situation arose because of the way you had stored the panels. What sort of weather have you been having ?
   Forget about clamping to mdf etc. In the worst case one would merely cut and re-join: two cuts with bandsaw and clean up would cost you less than 5mm on width....
   This is assuming the timber is acclimatised. Can you see if each 3" board is cupped? If these are straight then your edge jointing may be at fault-did you shoot by hand after machine plane?

   Philip Marcou
1. 
   Masrol | Dec 24, 2006 08:20pm | #6

   I am so sorry not able to reply you promptly. I was in a hurry to abort my computer cos my internet browser got corrupted with sort of XXX pop-up ads.

   My 3" W shop-surfaced lumber is straight and square, I had tested it with straight edge and enginering square. After reading you post, I did check them (the panels). It seems that the cupping only happened in between the joint. The 2 boards in the centre are OK (I glued two of them first, overnight, then I glued the other 3 boards in the morning . I did not glue all five board at one shot).

   Anyway, I think I had rather cut them into three and rejoint since I have extra 2/8" in width.

   Thanks Philip.    

    

   Edited 12/24/2006 12:21 pm by Masrol

1. 
   Quickstep | Dec 24, 2006 09:12pm | #7

   I'm not expert, but I've made my share of warped panels. and got weary enough of it to try some different things. There's nothing scientific about this, just stuff I tried that seemed to help. If you store a freshly planed panel on a concrete floor, it can absorb moisture from the cold slab and release moisture from the side that's exposed to the wam air above, causing the cupping. If you flip it over, it might reverse the process, but if you've got the spare width, might as well re-joint. 

   When I make really wide panels, I cut all the pieces a little bit oversize and let them sit in the shop for a couple of days. I then cut and joint them to size and glue up the panel, leaving them in the clamps until I'm ready to raise the panel. I then plane to thickness and raise the panel right away. After that, I try to get some finish on them as soon as possible to prevent rapid moisture changes.  Since I always finish my panels before assembling them into the frame, this works out for me.  

1. 
   philip | Dec 25, 2006 12:12am | #9

   "When I make really wide panels, I cut all the pieces a little bit oversize and let them sit in the shop for a couple of days."
   Yes, the important thing is that if they are to "sit", even for a short time whilst you are working on the rest of them between processes, they should be stacked with stickers to allow even air exposure as far as possible.
   Anyway, if one has many panels to do, it feels better to see them neatly stacked rather than sitting around at random. You know they will be behaving properly.Philip Marcou

5. 
   mrbird90 | Dec 25, 2006 12:03am | #8

   I have had this happen a few times over the past 40 years and sometimes you can dampen the cupped surfacd and clamp it wet side down to a flat board over night and when you take off the clamps almost all the cup is gone. It is worth a try. Once I just put the cupped side down on the grass for a couple of hours with the sun on the convex side and it straightened out in a couple of hours. Good luck

6. 
   colebearanimals | Dec 26, 2006 09:52pm | #11

   Hi Masrol,  Did you alternate the growth rings? This will go a long way in keeping wide panels flat.  This should help you the next time.

                                       Paul

7. 
   gb93433 | Dec 27, 2006 12:31am | #12

   When wood is kiln dried it is dried to an average moisture content. The outside will be dried past the target MC and then steamed to bring it up. That way the inside is dried to where it should be.

   Anytime you take wood off the outside of a piece of wood it will change due to the destruction of the equilibrium when milling the piece. When working wood it is best to mill it oversize slightly and then let it set awhile so it will stabilize and then mill it again. When I make cabinet doors one of the first things I do is to mill the lumber before I start the cabinets. The wood should be stacked in such a way that the pieces have equal temperature and ventilation on all sides. I stack the pieces on edge and cover them with a cloth tarp. Periodically I may turn the pieces of wood over 180 degrees until there is no more obvious movement.