I keep having trouble with glued up panels warping after I remove them from the clamps. I have had this problem with red oak and white pine. I buy the red oak in 4/4 and mill it to 7/8. The pine was purchased at 3/4 and milled just enough to get it flat. After running the boards through the jointer and planer I match them up and mark them, then glue and clamp with my Bessey clamps and let them cook overnight. Within 1/2hour of pulling the panel out of the clamps it will have a warp in it. As much as 1/2″. The red oak was purchased from a large hardwood supplier and sat in my shop stickered for 12 months before I touched it. Its very humid where I live along the Gulf of Mexico, in Victoria, Tx. Most wood I measure seems to be in the 12% moisture content range. I have no heating or ac in my shop, its enclosed though. I bought a piece of red oak recently from local supplier and glued it up as an experiment. Yes, it warped too. I have been watching it, as the humidity changes it goes from flat to warped. I expect it to change dimensionally but just cant handle the warp thingy. Some of the panels I have made for table tops I put support stickers across the back while I worked them and it kept them straight. When I glue up, i have air gaps under the boards, I don’t store them on or near concrete. I usually use gorilla glue for panels, water on one side, gorilla on the other. I have even gone back and ripped panels into pieces again, jointed, and had the same thing happen. Any ideas? Help !!!!! Warped in Texas.
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Replies
What kind of warp? Cup, bow, twist, something else? Is it always the same direction?
Are all your clamps on the same side of the panel?
You say you use water on one side, gorilla on the other. How much water?
Edited 1/22/2005 12:17 am ET by Uncle Dunc
A classic problem, you are using flat sawn wood and don't understand wood movement. Get a copy of "Understanding Wood" or the Lee Valley "Wood Movement Reference Guide" either will explain what happened and how to avoid the problem.
John W.
John,
We're starting to wonder if you co-authored this book? (Just jokin, mine is on the way from Amazon)
Personally, I believe movement and cupping of a table top, even if quarter sawn will always take place. Over 36" on 4/4, 1/2" is not much and it can get worse even if you do everything correct, depending on where the table eventually ends up.
The solution is the way the top is fixed to the table frame, not allowing cupping, but allowing for expansion and contraction.
If the design does not allow for pulling the top down in the right places, it is better not to use solid wood.
>> ... movement and cupping of a table top, even if quarter sawn, will always take place.Why?
Because wood "lives" and moves.
Biggest factor though is that a well made piece will last several generations and at some point in time will be likely subjected to a situation where equal moisture permeation is not allowed, such as a window facing East or West, with sun shining through.
Jellyrug,
I wish I had written "Understanding Wood", I could quit my day job.
It is frustrating to see so many people having problems with wood movement when it totally predictable. I am starting to get self conscious about repeatedly telling people to buy "Understanding Wood" but there is no substitute for the knowledge it contains. The Lee Valley publication is also good and, at $5.00 a lot cheaper, but it doesn't have the detail that Hoadley's book has, but it does cover the basics well and the wood movement chart is well designed.
By the way, in the interest of full disclosure, I work for Taunton Press, the publisher of "Understanding Wood", but I don't get any points, or any money certainly, for suggesting that people read the book. I recommend it because it is one of the few complete sources of information on the subject. If someone else published it I would still suggest that everyone go get a copy.
A flawless quarter sawn board will not cup by the way, provided that the finish and exposure to the air is equal on both sides. It will still expand and contract across its width with changes in moisture content, but only a half to a third as much as a flat sawn board. In a table top it is very difficult to prevent a flat sawn board from cupping while still allowing for expansion and contraction, the forces involved are quite strong.
John W.
Edited 1/23/2005 8:12 pm ET by JohnW
I am very new to woodworking, and love everything I am learning. I searched for this and see that it is from 2005, so I am sorry if this is too old to be replying too. But I just did my first true glue up for a floating shelf I am working on. It was 2 pieces about 8 inches wide, 44 inches long and has been milled too 3/4 thick. Shortly after I took them out of the clamps I noticed the panel was bowed greatly. I saw what you said about it being quarter sawn and I was like wahlaw that is my issue. But then I went and checked it and found it to be flat sawn. I saw the books you recommended and am about to order from Amazon. Any help in the mean time would be wonderful.
How wide are the boards? Are they quarter sawn ?
Width ranges from 20-31 inches. Not quartersawn, plain sawn.
Stantheman,
I live along the Gulf Coast too. I had a similar problem till I did some reading about wood movement. Are your panels warping/cupping as a whole or are individual boards doing the dirty work? If it is the whole panel warping, try watching your end grain. Make sure you reverse the curve of the end grain as you line up your panel to glue it up. It's easy to see if it is flatsawn. It completely cured the problem I was having.
Never had a quartersawn board warp, cup or twist. I always read that is the real reason why it was used for furniture, it is so stable. Ray flecks were just a the extra pretty thrown in.
Hope this might help.
Jimmy
as always I wish you enough
Stan, ALL movement in wood is related to moisture change. 12 % MC is ~= to air dried.
If you are bringing 6 - 8% kiln dried MC wood home, If you are not using right away, keep it wrapped with plastic to slow the MC gain.
If you are stickering KD lumber in your shop, you are taking it back to air-dried which will lead to problems when it is taken into a controlled atmosphere.
Hey buddy,
I grew up in Pt. Lavaca and have a lot of family in DeCosta (8 miles south of Victoria). How about that white Christmas!! Unbelievable. I now live in the DFW area and this time of year is always a challenge. Especially when we have those crazy temp/ humidity changes in a 24 hr period. First of all make sure that you alternate the grain of the boards. When viewed from the end the growth rings should look like this v^v^v^v. Hope that makes sense. Also NEVER leave a board or piece of plywood on the floor. When the sun comes up and the slab sweats it will warp instantly. finally never leave a board or panel laying flat on a work bench or anything like that. The humidity will enter the top, but not the bottom of the board. Always sticker it with at least 3/4" stickers. If the problem is cupping I would check to see if your jointer fence is set perfectly at 90 deg. Finally if all this lumber came from the same supplier, and thus the same mill/kiln, the lumber may be poorly dried. Never use 3/4 S4S lumber. Use at least 4/4 and even 5/4 is better, shoot for a final thickness of 7/8" or better. always mill the same amount from both sides of the board, flip the board over after each pass in the planer. When I have the time I like to joint and plane to an inch then let the boards sit for another 3 days or week. They almost always warp or cup some more. Then I joint and plane again.
Good luck,
Mike
If you can get your hands on the FWW Nov/Dec 2003 issue it has a very helpful article on this subject. The article is titled "Gluing up Tabletops".
Always leave the individual boards at full thickness - they should only have had a skim planing to help you orient the boards for an attractive panel. Then joint the edges and glue up.
You should flatten your panels AS A UNIT (and then process it to finish thickness) instead of working the individual boards to finish thickness and then gluing up. What you are trying to replicate is "one wide board in the rough" that might have been available a few hundred years ago. So, get as close to that concept as you can.
If you process to final dimensions before gluing up, you obviously don't have any 'room' left for flattening a panel that decides to buck and snort a bit.
This ought to work. Messrs. Goddard and Townsend did not have the benefit of Mr. Hoadley's book in the 18th century. It's a good book and by all means buy it. However, common sense and prudence will get you through your next project just as well.
This is where having some hand tools skills helps you out, unless of course you have a very wide jointer that you can use to flatten panels.
Don't process your stock to finished dimensions and let it sit around for days before you put it into the project. And as has already been mentioned, you should be working with stable lumber thoroughly acclimated to your shop.
Edited 1/24/2005 10:17 am ET by cstan
I found that when I finally started really cutting everything accurately warping problems seemed to vanish. Are your edges really straight and at a right angle to the surface? Can you lay a straightedge the length of the board and not see any gaps? Jointers aren't perfect and without careful checking you might not have trued the boards up enough.Also can you slide the boards together and they fit well and lay flat? Or when you glue them do you hunker down on the clamps figuring that when the glue dries everything will stay just like it was clamped? And of course gluing up any series of boards you'll still have to flatten the surface, they'll always be ridges. I don't own a jointer, I live in Southern California (where wood movement is caused by me or earthquakes-but almost never by moisture). I usally true up on my table saw and then run the boards on edge though a surface planer. So your tools are better. But I'll bet if you're just starting out you're making the smae mistakes we've all made: trying to get the max out of your lumber and not removing enough wood to straighten, you're solving joint problems with clamping strength and maybe your tablesaw or jointer technique is not as tight as it will be after a few days of determined and repeated practice. (I still make almost all the mistakes that's why I can list them so easily).
Will
I work with only hand tools. I joint edges of individual boards (previously very lightly skim planed with a jack) and then glue up. I never use remarkably warped stock for any project. After that, I process the panel as if it were one wide board as mentioned in my previous post. When I'm done the panel is flat, square, and uniform in thickness. I can square up and flatten any size panel since I'm not limited or constrained by a machine's capacity. For me to work individual boards to a finished state and then glue them up would be creating work. The only thing I'm concerned with is the panel as a whole.
I do the least amount of work I can to create a glued up panel, and then I bring everything to truth from that point.
My chief mistake is too much clamping tension. Clamping the bejesus out of a panel causes internal stresses and once you take them out of the clamps, they warp. Honestly, you need only enough pressure to bring the joint together and let the glue do its work.I am a big big fan of epoxies, and West System's is a nice gap filling glue that does not require much pressure at all. Indeed if the glue makes contact with both surfaces, you'll need a frigging jack hammer to separate the panels. This allows me to concentrate on nice flat edges with a jointer or joining plane.Regards,
Boris"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
There is often suggestions of reversing the grain "cup" of adjacent boards in a glue-up to prevent panel cupping. It seems to me that this will also reverse the grain in adjacent boards in the resulting panel.
My question then is, how would you plane the resulting panel if the grain reverses at each board? Or would you sand the panel in a large sander?
Brian
To answer some of the many comments (Thanks !) I start with 4/4 S4S and mill it to about 7/8". When I lay the boards out trying to match grain, I have noticed that the boards do not butt up well to each other. I checked my jointer with a small one piece machinist square in several places and it is square. I have run the boards on alternating sides to account for a potential 1 degree 0ffset that could exist (91/89). Now, we are talking very small gaps, but I can see them. It is possible that I am overclamping, applying too much pressure. Also, to answer one of the other questions, The entire panel warps, not just one board. Whats amazing, is my rough stock is about 8-12" wide and it stays perfectly flat. The only project where I didnt have this problem was were I used some old wood from a 100 year old house. (Pine). I made a raised panel blanket chest. None of the panels warped. Maybe those boards were air dried and not kiln? Hummidity around here is almost always above 50%, not uncommon for it to be 80%.
I attempt to orient grain in the same direction and in the most attractive configuration. This rarely results in the arrangment you mentioned.
I do a fair bit of gluing up of panels for tables and case pieces. I learned the following from Garrett Hack: Take one of the boards you want to glue up and put it in a vise, glue edge up. Put the mating board on edge on top so the panel to be is vertical. If the resulting two boards do not make a flatplane, all the glue and clamping won't help. I find it takes a jointing plane to properly mate the boards .
Good luck.
Stephen J. Gaal
I'm in Houston.. the humidity capital of the Western Hemisphere. Our climate here is truly sub tropical and there are some months (May through September) when it is simply foolish to attempt a panel glue up.
I recently did a panel glue up (19"X41") for a blanket chest top. I was using 3/4, S4S white pine.
I set the panel aside, on end, for three days while I cut the joinery for the other pieces. When I went back to apply the breadboard ends called for in the plans.. the top had cupped too much to be used.
For the second attempt, I brought the boards home, let them acclimate a few days.. and then cut, jointed and joined them. I immediately applied the bread board ends and, for good measure, added two cleats across the four boards on the inside of the chest top.. making sure to widen the bottom of the screw holes to allow for movement. It has now stayed flat and looks great.
Table tops I have previously made have stayed flat but these were milled from 5/4 maple or walnut stock. The species may have made the difference or else I just got lucky.
But from now on.. I plan to make my panels LAST so that I can do everything I'm going to do to them all at once.. including glue up, smoothing and the first finish coat, (both sides), and then go right to assembly.
During those months when the humidity is above 50 per cent I make panels only from sheet goods, dressing the edges with hardwood. I save hardwood projects for the drier, winter months.
Hope this helps.
Bill
Hey stantheman, for some reason the system let you join with the same name as mine. I thought they screened for that. I need to let sysop know.
User ID's, the name you use to log in, are constrained to be unique. Nicknames or screen names are not.
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