seasonal movement help please??

[Walt Caza]

Good Day to the Creek,
I found myself standing in the shop with a noodle scratcher, and decided to appeal to the Creek for help.

I am building an end table of QSWoak in the Craftsman style, designing as I go.
Just scribbled a few target dimensions and let sawdust fly.
Now it is time to glue-up panels for top and shelf, I am wrestling with wood movement. (better late then never?)

On the Limbert plant stand I last posted, I used an 1.125" solid shelf with a single seam centered.
It was flush mounted on cleats, with the crossgrain screwholes stretched to allow a bit of movement.(?)
This trapped shelf was prefinished on all 6 sides, and slip fit into the robust
mortise and tenon frame. Maybe not the safest bet, but the shelf is only
10" long, by 8" of crossgrain. I live with that stand, and am eager to see if time will blowup any joints.

I have been reading the popular reference 'Understanding Wood' by Hoadley. I find the shrink/swell formula not much help, as my variables
are a guess at best. He says quarter sawn moves substantially less...
My stock was alleged 6-8%mc when bought, it is sitting in my shop of humidity in the high 40%'s, and my home is central a/c to below 50% humidity all summer.
blah, blah, blah...

The question is:
Dare I glue-up a panel shelf like the Limbert plant stand, but mounted 1/4" below the top of the bottom stretchers? (preferred aesthetic)
Or should I slow down and figure out something to better allow seasonal wood movement?

The crude sketch is my idea to maybe ship-lap a 3 piece bottom, of equal widths that show from above
for appearance sake, with 1/8" gaps and mount them so they can move...
shelf size is 12" across the grain. (icky?)
I originally was going to not use the lower stretchers on the narrow front and back of the table, and just cap the shelf itself, but I liked the look
of that other shelf better, creating this whole pickle.
I used several homemade corner clamping triangles to ensure a good square frame, in case I do make another 'trapped' shelf.

As I have been building more furniture, people are showing interest, but I feel I cannot consider selling any solid wood pieces until I get a grasp of
how to make them last through the seasons....
Any thoughts appreciated,
Walt
:)

[Howard Acheson]

>> My stock was alleged 6-8%mc when bought, it is sitting in my shop of humidity in the high 40%'s, and my home is central a/c to below 50% humidity all summer.

To answer one of your questions. The wood may have been at 4-5% EMC when you brought it home. But, as soon as you put it in an environment of 40-50% relative humidity, it will absorb moisture to bring itself to about 8-9% EMC. So, it will expand during the period until it attains its EMC percentage.

You will probably find it useful to use the "Shrinkulator" at www.woodbin.com. Then click on "Online Utilities". All you need to do is plug in the variables and it will calculate the expected wood expansion/contraction.

You should also be aware that white oak is one of the more unstable woods. It's rates of expansion and contraction are quite large so adequate allowance must be made for the magnitude of movement.

There are a number of ways to mount a shelf in the manner I understand you are planning. The current May/June issue of Fine Woodworking has a good solution.

[Chris Mann]

The plant stand is such a small piece, it's not going to move too much. That said, anytime you capture a solid piece of wood between a frame, at some point you will run into problems (although I can't tell if this shelf is actually notched around the legs or not).

If I understand the design of the end table, the easiest solution is to just treat that bottom shelf like a frame and panel. Run a groove around your stretchers and notch out the legs. House the shelf in that groove (you can rabbit the shelf so the groove doesn't have to be the full thickness). You could also pin the shelf in the middle to stop it from shifting if you'd like.

I'd reserve "understanding wood" for those sleepless nights, a reference like "encyclopedia of furniture making" wood be a better reference point for the overall design of your pieces.

[Paul Simmel]

>>> Dare I glue-up a panel shelf like the Limbert plant stand, but mounted 1/4" below the top of the bottom stretchers? (preferred aesthetic)

Hey Walt, I’m trying my best to follow you here. If I read this correctly… On the table, you meant to trap a solid panel between the stretchers, only drop it down ¼” from the tops of your stretchers, right?

If the piece in question is dry fit, take up Chris’s suggestion and groove in a floating panel (this is a great solution because you wanted to drop the shelf down ¼” from flush anyway). If the piece is already glued up, drop in a solid panel between the stretchers like you intended, supported underneath by a ledger, and let it float there after allowing clearance for movement. You could treat it like a table top and screw it from underneath with slotted holes. You could even observe it over time. The 1/16” or so clearance between stretchers and shelf edge would be negligible… even if you kept the shelf flush with the tops of the stretchers, would it be negligible IMO because you really can’t see in there anyway. If you miscalculate, and see that over time the shelf is close to binding, you could easily pop it out and after a quick shave over the jointer, you’d be back in business.

[Walt Caza]

Hi All,
I ended up going with Paul S.'s approach, floating the shelf on cleats, with
a slight perimeter gap. I will watch it as summer humidity climbs, and take
off a couple licks with the jointer if more swell gap is needed...
I might do it different next time, but I did get the look I wanted on this one.

Thanks Howard A. for the link and reference.
Chris M. the Limbert stand shelf was not notched, but this end table shelf is notched. Yes, Hoadley's book is a dull read, thanks for the alternative.

The pics are:
Dowelmax panels flush with just a scraper...fast and pleasing!
Shelf cleats screwed into stretchers.
Shelf fitted, sunken shelf and the corner notch.

I have had big fun making this little table...
it is plenty rigid without screwing the shelf, I may let it float.
I am only in it for the laughs and the lessons anyway!
Thanks again,
Walt
:)

[Joe Chritz]

Nice looking stand. Is that fumed?

I use QS red oak (because I have a decent supply) but every time I see those huge ray fleck in white I get jealous.

The shrinkulator is a good site and I use it regularly.

Joe

[gary Zimmel]

Walt

Nice looking table... Love the mission style and the QSWO.

One question. Did you use dowels for all the joinery?

[Walt Caza]

Hello again,
Joe, I have really been enjoying the Arts & Crafts movement lately.
I want to fume, but have not tried it yet. That little Limbert plant stand
would have been easy to tent due to it's small size. Maybe next time...
http://www.sawmillcreek.org/showthread.php?t=81043&highlight=Limbert

Hi Gary, my experimental end table is held together with 40 traditional mortise and tenons. I only used a few dowels to keep my panel glue-ups
flush. I will post this when I find time to put a finish on it.
be well,
Walt
:)

[Jesse Cloud]

Lots of good advice above. I just wanted to add that we really need to plan for worst case wood movement. Maybe your table will be passed down through the family and moved who knows where.

Case in point, I made a lot of furniture in Maryland, which is so humid in the summer you always feel like you are swimming. Now I live in the high desert of New Mexico. Today's humidity is 3 per cent. Nothing has cracked so far.;)

[Paul Simmel]

Very nice, Walt.