Suggestions for reducing bow

[Brian Penning]

Any suggestions for reducing the amount of bow I expect to get when I glue up about a dozen 1-3/4" thick boards, 4-5 inches wide, 18" long?
Going to be for a bench. Similar to below out of cherry. The grain orientation is going to be all the same(cupped up) because it looks best this way.
Should I joint and plane the wood and let it sit for a while(how long?) then joint and plane again to final thickness?
TIA

http://www.michaeldoerr.com/images/p_chair-dble.jpg

[Joe Chritz]

Wood will do what wood will do.

If it is properly acclimated to the final location you shouldn't get any serious movement.

If there is any question about the wood being dry enough, either hit it with a moisture meter or let it sit a while.

Also, it is never a bad idea to mill and then let it sit a bit and do the final milling.

If you want to know how to glue that many and not have the clamps force them out that is a different animal but also easy to overcome. I guessed you were talking about seasonal movement.

Joe

[Cliff Rohrabacher]

I'd joint and plane the pieces just as you normally might but, I'd take the extra step of marking which side went against the jointer fence.
Then at glue up, I'd flip 'em alternately to let any tiny error in the fence-to-table relationship work itself out.

I don't have a biscuit or domino or dowelmax so I just use a slot cutter on the router table and insert little splines to get a precise, slip-&-slide free glue up.

I use Pony clamps with double extra heavy black iron pipe.
They will induce bow in a glue up so I do one of two things for that.
1.) I clamp from both sides of the glue up to even out the pull of the clamps.
or
2.) At both ends of the glue up I use big C clamps to squeeze the glue up between jointed hefty maple members running at 90 Degrees to the glue lines. This forces the wood to obey during glue up. I use paper to keep the glue from making the supports adhere to the work.

In your case with all those many strips I think I'd build a clamping frame just for that job letting me have the benefits that I get from #2 (above) but without all the muss and fuss of having clamps every where and needing the twelve or eighteen arms I normally need to juggle all those clamps and chunks of wood and paper. .

[J.R. Rutter]

From the picture, I don't think that you will have problems if the seat is attached to the rails below. Are you going to do flat seats or bevel the edges of each stave slightly to get a curve? If you do a curve, I would glue up in sections of maybe 4 staves at a time. It would be helpful to know your starting and expected ending MC. As wood dries, the growth rings will try to straighten out, so would bow up in the middle in your case. This is perfect, since it is easier to attach securely in the middle and the tension will help keep the ends tight to the rails. Be sure to allow the seat to expand / contract side to side, like you would for a table top.