bowed boards in a table top?

[hugh lonner]

I am trying to build a 60x30 red oak table. I don't have a jointer (yet) but do have a planer. I had the lumber yard joint the boards before I brought them home, but two of the 5 boards I was going to use for the top have bowed a bit so they rise about 1/3-1/2 an inch at the ends relative to the middle. I was going to use biscuits to help align the top (along, of course, with glue along the joints).

To get the best looking top (ignoring bowing) one of the bowed boards would be on one end and the other would be a few boards away toward the middle - one bowing up and the other bowing down.

I've planed them down to an acceptable thickness, but could take off about 1/4" more before it gets too thin.

Will the biscuits and glue be enough to straighten the boards out or do I need to find another solution? I don't have easy access to a jointer and the lumber yard is pretty far away. (In case either detail factors in, the wood was Kiln Dried, and also I might mention that it is easy to push them down, but obviously when I let go it springs back up.)

thanks for any advice,

Hugh

[Lee Schierer]

You can try to glue them up as is, but most likely it will come to grief.

Try this, take your boards outside the next sunny day before the sun gets up too high. Put the concave side down against your grass. Come back every 30 minutes and check the boards. If they straighten out immediately take them inside and stack them with stickers between each piece and as much weight on top as you can find. Let them sit that was for about a week. Then check them again. If they are still straight use them but be sure to keep them stickered and weighted until they are in your table top. When the top is assembled make sure you leave it so that air gets evenly to both sides and finish both sides equally.

[johnny means]

How much of the the finished panel would the bow boards make up? A couple of 5" boards across 30" probably wouldn't be a problem. Two 10" boards would be a more of a problem. Also is your table going to have an apron or a stretcher right beneath the top? Such a small amount of bow is easily over come with either of these.

[hugh lonner]

Thanks for the advice. Johnny, it is two 5-6" boards, but I am making a trestle table without an apron, so the nice apron fix is out for me (and the trestle is too low to help).

On the bright side I did just finish all the mortise and tennons and assembled the base and it worked about as well as I could have hoped (as a relative beginner).

By the way Lee, in honor of your attached footer on your message and all the good advice I keep getting here (as well as savings from the deals and discounts page) I became a contributor today.

[hugh lonner]

For stickers, will 2 sided carpet tape do? Should it run most of the length? Perhaps I"m over-thinking it. Today is that next sunny day!

Also they almost seem to be getting more convex, so I thought I should confirm that we really do want the convex side down (ie the center of the board is up in the air and the ends are on the ground).

thanks again,

Hugh

[David DeCristoforo]

It would be "better" to incorporate the bowed boards so that they both go the same way and that they are both "sandwiched" between straight boards. Biscuits will help get the surfaces aligned so that you can glue up the top without too much of a fight. I would try to make the top with the bowed boards concave side down. It might not be the best way to orient the boards for appearance and grain match but it's rarely a "perfect world". In a perfect world, you would be able to make up your top out of straight stock and use the bowed boards for something requiring shorter pieces. In the end, that would be my "best advice" anyway.

[Henry Ambrose]

They are likely moving because there is a difference in the internal and ambient moisture content at the opposing surfaces of the board. It might be a result of jointing one side and not the other. Generally you should try to remove equal amounts of wood at the same time from both sides of a board to keep this from happening.

Re-jointing would be a good solution. Maybe better - buy two more boards. I think its worth a little extra effort to give yourself the chance for a well finished project. Don't short change yourself.

That said, it'll probably be OK with biscuits. And you might try dampening one side as noted above.

[Glenn Vaughn]

For stickers, will 2 sided carpet tape do? Should it run most of the length? Perhaps I"m over-thinking it. Today is that next sunny day!

Stickers are boards that are used as spacers when stacking lumber - my supplier uses 2X4 pieces.

[Chip Lindley]

The two bowed boards might be *equalized* by using biscuits to join them to each other, orienting one with bow up, the other with bow down. When clamped together the two forces will counteract each other. Theoretically, you end up with a *straight board*!

Before applying glue, dry-fit the boards together. See if they straighten out. Worth a try!

[Lee Schierer]

Thanks for the advice. Johnny, it is two 5-6" boards, but I am making a trestle table without an apron, so the nice apron fix is out for me (and the trestle is too low to help).

On the bright side I did just finish all the mortise and tennons and assembled the base and it worked about as well as I could have hoped (as a relative beginner).

By the way Lee, in honor of your attached footer on your message and all the good advice I keep getting here (as well as savings from the deals and discounts page) I became a contributor today.

Thanks for becoming a contributor. I get more than six bucks worth of advice here every year.

[hugh lonner]

So the sun didn't totally get rid of all of the bow, but did most of it. I decided to try a dry fit of the biscuits to see if that finished it off and it is close, but not perfect. I'm letting them sit for another week before proceeding, but I did have another idea/question...

I was going to start the glue up in stages and send the biggest sections that would fit through the planer (3 sections, one with 1 board and two with 2 so they would fit), but could I send the first two through with the biscuits in place, but no glue, then pull it apart do the same thing with the second and third board, then third and fourth, then fourth and fifth, and repeat a few times taking super light passes and setting a final depth stop to try to plane the whole thing together or is that bound for failure? I put in enough biscuits to make it a fairly tight joint in anticipation of the bowing issue so it seems like they might go through as a single unit, but I"ve never heard of anyone doing this so I'm afraid there may be a reason.

Hugh