I made a $200 mistake, and bought some beautiful Walnut boards, but when I got them home and tried to run them through the joiner, I notice they were severely bowed. By bowed, I mean the ends lengthwise are higher up and curl up than the center, like a “U”. The bow is fairly severe, more than a quarter of an inch over a mere four feet. This is 4-4 stock.
This is what I did to straighten them out. I ripped them into about 3 inch wide boards, alternated the bows, one up, then one down, etc., bisquited the devil out of them, and with some pressure managed to get the bisquits aligned, which took the bow out. Glued and clamped it. Sanded and planed it smooth (there was still some high and low spots)
Now the grain doesn’t entirely match, and it is more like 11/16ths now, but at least I didn’t throw this lumber away.
Any comments? Is this a correct way to remove a bow?
Thanks.
Kevin
Replies
Ahh, no. The minute you try to make something of your "new" board it's going to slap you upside the head -- given all the kinetic energy yearning to be free in that wood. Another solution: you could have cross-cut the wood into one inch segments and the bow would not have been noticeable. (Just kidding) But there is a little bit of truth there in that coss-cut idea.
Last time I had some bowed boards, I threw them out on the lawn, concave side down, let them pick up some moisture and straighten a bit, brought them in, stickered and weighted them, let 'em set for a few weeks and they were nice and straight.
Cut it up and use it for firewood. You screwed up, plain and simple.
"Cut it up and use it for firewood. You screwed up, plain and simple"
No. I'd cross cut...and then use for relatively short parts. Walnut is a good, stable and relatively well-wearing wood and hence short sections make for good wooden drawer glides or runners/kickers.
The other problem with flipping the boards is possible problems with grain direction.Tim
Whatever you feel like doing with it. Heating your house or shop with it is not necessarily a bad thing, or a worthless endeavor. Fuel is fuel.
Seems like to me you're going to have to dance around all the biscuit joints you've cut in the stock.
I had a problem once with poplar. I painted some solid doors outside in the hot sun. Went inside for some lunch and came back to find them severely bowed. After some severe language, my wife suggested I just bring them back inside and see if they would come back if weighted down. They did (she never let me forget it), and I learned from it. Try stacking it with some good weight on it and see if it won't come back. At the cost you paid, it's worth a try. Best of luck.
A very reasonable strategy if he had not already ripped, biscuited and reglued the stock ruining any chance of grain match.
Very good point. Unfortunateley some educations are costly. I've made some nice expensive kindling before. Although it does start fires fast.
Could allways rip it into small strips for cutting boards?
I usually burn monuments to my stupidity and I've had plenty.
Update:
Actually I did let the boards rest for about a week and nada. Funny, they were reasonably straight when I purchased them, but for some reason, when they were cross-cut into table top length, 4 feet, this whole board sprung. Its next door neighbor, which I think is an adjacent cut, because of sap wood and knots lineup, did not spring. Go figure.
So I let them lay around the shop for a week, and nada. I even put them in cawls, clamped to my bench to straighten them out over-night. They sprung back in seconds.
So yesterday I ripped them, reversed the grain and the bow, bisquited them, glued, and clamped them up. Yeah, I'll have to work around those biscuits but its better than firewood. You don't notice the grain; well maybe a trained eye might, but SWMBO sure doesn't, and they make a nice something; just not my table top.
So off to the hardwood store again today, and the owner says yes, he reverses the bow all the time on stubborn boards and glue ups.
So there is a bit of difference of opinion, at least on my end.
If I have a bowed board I absolutely must use I use a process I call reverse bent lamination. Resaw the 4/4 boards in half and glue them back together on your bench top or any other flat surface. Let dry and then treat like any other straight rough piece of lumber.....Don Kondra - Furniture Designer/Maker
Don:
Do you glue them back kerf to kerf or are they reversed somehow?
I would think that once resawn, the same board would be still bowed, except there would then be two boards which were bowed.
Interesting technique.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Kerf to kerf, if you are careful resawing there is no need to clean the cut before gluing....
Don Kondra - Furniture Designer/Maker
And the mere act of resawing relieves the stress so that the board is straight again, once glued up?
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
I think the idea is to rotate one of the resawn boards along the long axis such that the outside show face is now glued to the newly exposed face on the other resawn board.....in effect, canceling any bow out.Tim
Not.... :)
It is the same idea as bent lamination which takes strips from straight boards and then laminating them back together on a form to make a curve.
With this process you are taking curved pieces and laminating them back together to form a straight board.
Ideally laminations are done in uneven numbers, for instance three or five or seven, etc.... but this process has worked for me with just the two pieces. ie. cutting a 4/4 board into two 1/2" pieces.
Don Kondra - Furniture Designer/Maker
Edited 5/11/2004 3:55 pm ET by Don Kondra
Essentially that the re-sawn boards are placed in the same juctaposition (sp?) but the board has lost its spring for some reason?
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Lumber will want to cup opposite the direction of the growth rings. One possible strategy is to relieve this tension is cutting a kerf with the grain, on the face that will not be seen.
Wood will cup opposite the direction of the growth rings when it loses moisture, when the wood gains moisture the wood will cup in the opposite direction.
John W.
The idea of odd numbers for laminations applies to alternating crossgrain like plywood. Even numbers are fine with the grain going in the same direction as you have proven.
Kevin,
Ideally you should have brought the boards home and stickered them and let them stabilize to the relative humidity of your shop for a week or two. It is quite likely they would have changed in their flatness. Although it is possible that the bowing might have gotten worse not better, the more likely result would have been that the boards would have flattened out.
John W.
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