Mission slats - getting flat and staying

[jon hamer]

For my first attempt at mission-style furniture, I'm making a nursery set for my first child, to be born in October. So far, Iv'e made a dresser and am working on a crib, one with a lot of slats (of course).

The slats are going to be 27" long, 1/2" thick and 1 7/16 wide.
Materials:
I'm using 4/4 white oak. I have had the wood in my shop for about 3 weeks, it came from a climate-controlled warehouse that deals exclusively in high-quality cabinet materials. (so it was dried and stored carefully when I got it). It is super-humid here these last couple days, but I've turned on the AC today.

What I've got so far:
Today- I cut rough blanks from 4/4 white oak oversized so far, they're 1 1/2 wide, still 1" thick and 8' long. And many of them are crooked 1-2" over 8'. I want to end up with reasonably straight slats like I see on all the mission furniture that everyone else seems to have made just fine.

I've still got plenty of stock to work with to straighten them.

My plan:
Cut to length.
Face and edge joint the slats on two sides, then saw them parallel, slightly oversize, then joint the edges and faces once more, round-over the edges and cut the tenons.

BUT: how do I ensure that I'll end up with reasonably-straight pieces when I'm done? Should I wait for any period of time before I joint them?

Do i need to finish them RIGHT away once I glue up the 104 mortises? Can I apply anything before I stain to slow down wood movement before I get to stain and polyurethane?

Thanks,
Jon

[jon hamer]

I should add that not ALL of the wood warped when I ripped it. 80% is really good, just a few cuts from certain boards warped. If I get them to their final dimensions (and they're still flat), will they stay that way? or is the wood STILL bending, just more slowly, after the cut?

I've been reading and suspect that the wood was possibly not dried correctly, or didn't like the transition from the warehouse to my basement....

Jon

[Mitchell Andrus]

If the wood is going to misbehave that badly its best that it happens now rather than later.

Sometimes, cut more parts than you'll need and use the ones that behave badly for something else. You can't get the wood not to do that. Even properly dried wood can have an internal tug-of-war that relaxes only when cut. I use a lot of mahogany. Ripping 2" off of a 14" wide board sometimes makes me laugh at the twists and bows I end up with. Just gotta pick another piece and move on and use the first one for smaller cuts where the parts can be ripped thinner and/or glued up as a panel.
.

[Jeff Mackay]

The boards that are warping that much sound like "reaction" wood to me, or wood that was improperly dried in a kiln. To minimize the waste (those crooked pieces), try to take approximately equal amounts off of each side of the board. Face joint. Take an 1/8 of an inch in thickness off the other side with the planer. Wait a few days. Face joint the planed side, take an 1/8 of an inch off the other side with the planer. Repeat until you're down to the right thickness.

Jeff

[Henry Ambrose]

Chop 'em down and let them set for a few days, then select the straightest for your project and joint/thickness plane the same amount off all sides of each piece.

[jon hamer]

Thanks Jeff and Henry. I'm going to try what you've suggested. I got it close, but I might have shot myself in the foot by dimensioning the pieces I've done so far too close.

I experimented tonight with face jointing all of the crooked pieces, then thicknessing them, face jointing (again) all the curves as they developed (took 1/16" passes off alternating sides on the planer), finally thicknessing them what is probably going to be too close to the final dimensions. I'm going to wait a few days, see how they react and adjust my plan. I'm sure I'll end up leaving the rest oversize for a week or so, then jointing and planing again to final size.

I did a trial run with 1/5th of the total slats, hopefully they won't all go nuts on me. I can replace them if that happens to be the case.

Is there any chance that rift-sawn oak would have less internal stress?

Thanks!
I'll update with my results.
Jon

[Joe Chritz]

Quarter or rift sawn is almost always better behaved. It depends a lot on why the wood is acting up. Improper drying or reaction wood (how the tree grew) are two big suspects.

Generally by starting a bit oversize and re-straightening once you can get straight pieces. Anymore I cut all my stuff oversize and try to let it sit a day before final sizing. Doesn't always happen but sometimes.

I also find it usually moves immediately. If it is moving a day or two later that could be a different problem all together.

Joe

[John Thompson]

I'm gluing up 34 slats on a Mission Twin bed this morning. 17 are 15'' long and 17 are 33" long. All are QSWO. I chose the straightest boards from my batch and then cut them down to 19" and 37" respectively. Two inches allowed for rare but possible end snipe and 2" allowed for tenon lenght on each end. Planed them to 3/4" which is how thick they will end up and then ripped to 1 1/8" with 1" wide the intended width.

I allow 1/16" for each side before taking to the jointer which allows two 1/32" passes on each side. The reason is if I mis-judge the grain direction which is rare but happens.. I reverse the piece for the 2nd 1/32" pass so they come off the jointer baby butt smooth. After this process they are final sized in lenght and ready to cut the tenons. In lieu of cutting 17 I cut 20 of each. As Joe stated any warp will usually occur immediately.

I simply purchase more than necessary as you cannot read internal wood in most cases from the surface but it will show when ripped. If that means culling a few pieces then I cull them for use elsewhere. QS or rift sawn is usually very stable but internal stress does occur and that's a fact of life. I just deal with it in the manner I described.

Good luck...

[Mike Wilkins]

To use slats that are 1/2" thick, you must use straight-grained lumber to start with to avoid movement. Even with that you may still get some warpage out of some sticks. Better to cut a couple extra just in case.

[John Thompson]

To use slats that are 1/2" thick, you must use straight-grained lumber to start with to avoid movement. Even with that you may still get some warpage out of some sticks. Better to cut a couple extra just in case.

Totall agree about the 1/2". The thinner you go on thickness the more prone to warp if indeed their is internal stress. Another fact of life.

[Sam Layton]

Hi Jon,

If you need your slats 27" long, don't start with an 8' board. If you cut your rough board down to rough length size (couple inches longer than you need) you will release some of the tension in the wood. After your rough stock is cut to rough length then join,and plane, etc. You notice John and Henry cut to rough length first, then began the milling process.

Sam

[Prashun Patel]

4/4 oak isn't usually so warpy.
I say just cut a bunch extra and keep the ones that stay straight.

Rough Rip and plane them to with 1/8-1/4" now. Joint and plane them to final dimensions as close to assembly time as possible.

[John Thompson]

Just a note Jon as I shot a picture a few moments ago as I am about to final glue my assemblies based on this statement you made...

"Do i need to finish them RIGHT away once I glue up the 104 mortises? Can I apply anything before I stain to slow down wood movement before I get to stain and polyurethane"?

Thanks,
Jon

I am retired and pump out a piece of A & C in my shop every 1-2 months. I always finish my pieces before I assemble and glue by blue taping off tenons.. mortices.. dadoes.. etc. before I do the glue up. I even do the wax and final rub-out before the fact. Much easier IMO and especially with slats. My slats are 3/4" x 1" spaced 1" apart. Imagine how difficult it it to get into nooks and crannies with stain.. finish.. scuff sanding between coats then wax and rub-out with so many obstacles created by the finished piece after glue up. A PITA to say the least and only the very patient will survive large projects often waiting until after.

Not trying to tell you how to approach.. simply suggesting what I have found over the years for you to make your own decisions on "how"..

Good luck with your projects and work smart.. it saves time.. material and effort allowing you to move on to.... "next"!