Hi – I posted this on the KNOTS part of the site, thread 38996, but would like you to comment (or any other expert). I am especially interested if sawing kerfs in the wood will help. thx
I have several dressed 5/4 curly maple boards about 9′ long that were recently resawn from 12/4 material. Some of the boards now have a 1.5″ bow the long way, i.e. when placed concave side down the center of the board is 1.5″ off the ground. The original 12/4 boards did not have any bow in them. I want to make a 8.5′ table from these boards and need to remove the bow. I will not plane them since I want the look of a thick table. The bow is medium strong, i.e. i can put 2 boards together concave face to concave face and squeeze the bow out of them with my hand. I have clamped the bowed boards together with a reverse bow for a few weeks hoping it would less then bow, but that has not really helped.
The only solution I can think of is to get a few 7′ or 8′ lengths of angle iron and screw them into each board the long way to get the bow out. I was also thinking of putting in saw kerfs into the boards about 1/2 in and across the grain to diminish the bowing pressure. Has anyone done this? Seems reasonable but then again, many things do but aren’t.
Some of the boards do not have a bow so I am thinking that when glued up they will help keeping the bowed ones straight. I will use plenty of biscuits between the boards. Any suggestions/experiences? Thanks alot.
Replies
That's a tough one- whenever lumber is resawn you should expect a significant amount of distortion/ movement- all of the tensions that were in balance as a thicker piece have now been drastically changed and the result is thinner boards with significant bowing.
If you are unable to face joint and plane parallel (the best solution) then I think I would probably glue up as flat as you can. You mentioned that some of the boards are straight which will help keep the bowed ones straight. I do not think I would do the kerf cutting- but it would be interesting to try it out on some scrap pieces and see how it works. my experience with that (albeit limited) is that the kerfs eventually telegraph through and you can sometimes see them.
I never use biscuit or dowels in an edge joint- The glue joint is already stronger than the wood itself so the biscuits are not adding anything (except a little $ in the pockets of the biscuit manufacturers!)
I would consider beefing up the table base- possibly thicker aprons and maybe even a strongback down the middle to help keep things flat (use extra table buttons to hold the top securely but still allow it to expand and contract.
Good luck with it- let me know how it works out-and next time resaw thicker so you have enough material to reflatten the boards after the resawing
Bob Van Dyke
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