Ok all you enlightened ones, here is a question. I am making a hope chest for my sons wedding. The wood of choice?…cherry. Now I took a board that was 12″ wide and 10 feet long and cut it up so as to make the top out of 2 boards. I flippled the board so that the groth rings go in opposite directions so as to help prevent cupping. Dont ask me why I did this when I planned to put braces on the underside of the top to prevent cupping anyway but I did it. So after glue up I find I have a distorted board. When you hold one side flat on the bench one of the opposite corners comes off the surface by an inch. My plan to correct this problem was to make a frame to go on the bottom side. Flatten the top by clamping it to my bench top and then fastening the frame to the top. It doest seem to take muck force to flatten the top when I push down on it. Will the frame correct this distortion? Is there a better way to do it?
Wicked Decent Woodworks
(oldest woodworking shop in NH)
Rochester NH
” If the women dont find you handsome, they should at least find you handy……..yessa!”
Replies
You should have jointed the boards flat first. Saw the piece where the twist begins, joint both boards,reglue. The result will be thinner than the originsl, how thin? Can't tell until you saw and check it with paralells.
If you do not have a wide enough jointer, saw into workable widths,joint the edges. When you glue them up match the grains, you won't know where the joints are if you do it carefully.
mike
John,
The best solution to your problem is to back out of it, and start over. Rip the bds apart, and reflatten them, if you have enough thickness, to get rid of the twist. Re join them, if you have enough width.
If that isn't an option, I've had good luck with a diagonal brace. Run it from one of the "high" corners to the other. I'd make the brace 2 1/2 or 3" wide, 7/8" thick or thereabouts. Plane or joint a hump in the middle, so the ends are pulling down on the corners of the top when you screw it fast. Allow for movement by drilling the holes for the screws oversize in the brace. If anyone asks about the brace, tell 'em it's there "for strength".
As an aside, I like to put a pretty heavy mold around three sides of the top of my blanket chests. I work a groove in the edge of the molds applied to the ends that mates with a tongue worked on the end of the top. Glue the mold on the front, the mitered corner, and back 2 or 3" on the end. A nail or two holds the rest in place, and the tongue and groove keeps the top flat.
Regards,
Ray
I assume you are talking about an X braceing under the lid, correct? Couldnt I achieve the same results with aframe arrangement? I would make the frame with stout material; 7/8 X 1 1/4 or so probably sugar maple. Assemble the ends using dovetails or long screws. the frame would just clear the inside of the box opening when the lid was closed. I was figuring that if this would work I could put a hinged cover over the frame and say the compartment is for important papers.Wicked Decent Woodworks
(oldest woodworking shop in NH)
Rochester NH
" If the women dont find you handsome, they should at least find you handy........yessa!"
John,
The difficulty with a rectangular frame is that the stress will be all at the corners, which will want to pop the corners apart. A diagonal brace (doesn't have to be an X, except for looks) will be pulling directly along the line of the twist. If you must use a frame, I'd want to go deeper than 1 1/4", more like 2" or 2 1/2". That'll give you more space for the old "important papers" trick, and maybe a pair of sliding bypass doors. Be sure to allow for seasonal movement when you attach it, and set back from the front edge to allow for the swing of the top as it is opened.
Regards,
Ray
cherryjohn ,
I would agree with Ray . I would slice the joint apart , joint the edges to get the seam right , What I think also can happen is that when you clamp the panel up , you have the ability to rack it in or out . I sight down the glue up along an edge and move the clamps in the correct direction and the panel moves also . I do this on all doors to reduce warpage . The panel will set in the position you rest it in .
good luck dusty
Hi John, since I've seen the top, I had an idea. I don't think a frame would help it that much as it is. I wonder if the joined edges are a bit out of square, or more correctly, contributing to the twist. I think I would rip the top down the center, lay the two boards nice and flat and see if making the edge joint at a slight angle would help make them mate flatter. I didn't ask you how you went about the glue up. The boards seemed to have a bit of belly in them. You may need to rip them in several strips and do as above. It's pretty hard to reference a jointer, hand or power to a twisted or bellied board. One way is to clamp them down flat with an appropriate space in between and run a router, guided by a straight edge, down the joint, cutting both edges at the same time. You'll need a piece of plywood or something underneath to cut into. This is the same way we fit Formica. A template guide in the router base with the router riding on the straight edge will help keep the bit perpendicular. There will be some humps at the joints but you can level them much easier than the large twist. When you glue back up, use some cauls to hold them flat to the bench as you pull them together, wax paper under so you don't glue them to that nice bench of yours.
If you still think you will need a frame, one option may be to cut 2 1/2"-3" off the top of the box. This will give you a frame that fits flush with the box and won't have to fit inside. Figure your dovetails accordingly. The hinges and a couple of latches will pull what little twist is left. If the boards are just too twisted to work, you'll just have to break down and build a new one. It's not like you don't have enough wood kicking around. Say hi to Sharon.
This simple little project is turning into quite a conundrum, eh Hippie? You're right about one thing. It isn't like I don't have more cherry to make another top. I just hate to get rid of that beautiful tiger stripe cherry top. Sharon wants to invite you and your wife along with Buzzsaw and his bride over for dinner sometime this fall. Maybe we can put a fire in the fireplace and get all cozy..pick one! ( fireplace that is)Wicked Decent Woodworks
(oldest woodworking shop in NH)
Rochester NH
" If the women dont find you handsome, they should at least find you handy........yessa!"
I suspect that using 12" wide boards was the real source of the problem. Even if they were dead-flat after you cut them to length, the gluing and clamping may have introduced stresses that caused twist while the glue dried.
I've found that when I use narrower boards (~5" max) and flip the growth rings, I rarely have a cupping or twisting problem.
I would consider ripping the glue joint and then ripping the boards in half, joining the edges, and regluing the top - alternating the growth rings. This should flatten it and prevent more twisting.
Dave, I suspect you are right. Normally I would be using 5"-6" wide boards for a top like this and in the past , doing it that way, I didnt have a problem like this one. I just had the urge to use those 12" wide boards. Maybe taking that top down to (4) 6" wide boards and regluing them will get rid of the twist or most of it. Its worth a try I guess. If that doesnt work, well grab another board and start over.Wicked Decent Woodworks
(oldest woodworking shop in NH)
Rochester NH
" If the women dont find you handsome, they should at least find you handy........yessa!"
Unless the two boards are very straight grained quarter sawn, it very unlikely that the top will stay flat during even minor changes in humidity and that is probably the cause of the distortion you are already seeing. You are expecting more stability out of the wood than is reasonable to expect.
This type of top, while beautiful in its simplicity, rarely stays completely flat even with bracing installed on the underside, especially if the piece is in an environment with large seasonal humidity changes.
John W.
Just me so...
I would use the frame of your own style and put in two three.. (Not sure how big the top is) sliding dovetail braces (underside?).. No glue in the dovetail.. Maybe a peg at the center...
If you can flatten by hand should work fine.. BUT to cut that dovetail slot it has to be flat!
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