Another obsessional wood movement question...

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What about things like production tables, etc. then George? The construction that toller posted the pic of is common place construction.
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-Mike-
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Imagine if you look you'll see this is not the case. For instance, the lower shelf of Toller's sofa table, made with a single board of butternut, if tightly held between the legs has a 50/50 chance of popping or loosening the joinery as it expands beyond its ability to compress what holds it and itself. Simple remedy is good woodworking, either pinning center on the cross-grained rail and floating both ends with a sixteenth gap by making oversize holes for the pocket screws, or realizing that there will be a front - where the drawers open - and a rear, pinning flush to the leg at the front, floating the center and rear, allowing the full eighth expansion where it's not noticeable.
Using your example of frame and panel construction, which, I assume, you know is designed to maintain virtually constant exterior dimension through changes in MC, you always want to finish the panels prior to framing them, because they can shrink and reveal bare wood at their edges. If made too large when dry, they can find the weakest glue joint in the frame and destroy it, or finding themselves the weaker, compression set their fiber and develop a rattle. A competent woodworker anticipates and compensates for all these.
I'm sure you've seen your share of tables with split tops (and chairs with split seats) which were restrained without regard for wood movement, as well as those with ears from having well-varnished tops and virtually finish-free bottoms. Then there are the open corners on mitered wood ... the list is endless. It's never been my objective in woodworking to emulate the shoddy manufacturing processes of commercial work. Therefore I use techniques designed to accommodate future movement.
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This is where I see his construction differently, as viewed on the web site. He has a support between the front and rear legs upon which the shelf sits. I would agree that if it were simply a piece of butternut, he'd have problems without a doubt. What he has though, with the support screwed in place, is very much like the standard construction of any dresser or other piece of furniture. Secured to the support, the butternut is not going to move as it would if it were simply sitting exposed to the changes in climate. Such is the nature of furniture construction. All furniture is constructed with cross grain construction and it is constructed in a rigid manner. Yet - it does not expand and contract so as to create a wobbly piece after a few cycles.

I fully agree that this would work, but I have to keep going back to ask the same question - and I'm not trying to be difficult with you George. I'd be reluctant to float the board as I'd fear cupping or bowing. Those two possiblities are something I'd consider to be more likely. Look at a dresser. It has to contend with cross grain expansion as much as any other piece of furniture does but the top is not floated. It is secured to the frame rails. Since however, he's fitting a piece of wood in between the legs, I could see where a very slight shave might be OK, to allow for some movement, but even that I'm not sure is necessary, since the shelf will be united with the support and the support being long grain, will limit the movement of the shelf.

Precisely the point that I made. The panel, while floating is only doing so in that it's not glued in. It's not loose though, when it's fabricated. In other words it won't rattle about. Yet - it does not push the joints apart as it absorbs moisture. It is constrained by the rest of the wood around it.

As well, I think it could be said of everyone here that they pursue proper woodworking techniques. Yes, I've seen bad fabrication, but I've also seen excellent fabrication. I tend to base my observations, my practices and my thoughts on those examples of excellent fabrication. Basically, a wordy way of saying "ditto".
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You are - sadly - mistaken.
Get a good book on woodworking. To begin with _Understanding Wood_ by R. Bruce Hoadley.
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"toller" wrote in message

Sorry to say it, but your design, as shown in the photo is probably not the best for longevity. :(
Then again, it may last forever.
Next time consider using M&T joints for the "rail" (your "support") between the legs, and attaching a "cleat" to the inside of the rail as the shelf support. Then attach the shelf to the cleat with screws in oversize or slotted holes.
Here is poor picture, but a much better way, but not the only one, to attach a lower shelf between table legs:
http://www.e-woodshop.net/files/ShelfSupport.JPG
Be particularly wary of the advice you've received in this thread to "ignore" cross grain situations ... it is simply wrong and misguided.
Hell, just ask to see some samples of their work before making up your mind to rely on such advice.
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realized I had a problem the side and legs were all glued up.
But why not screw to the two legs, and put a support under the shelf, attached to the legs in mortises; attaching the the shelf to the support with the slotted holes? That is what I thought about doing before I decided it wasn't practical at that point of construction. (another problem was that I had never done a mortise and tenon before; but I've never done a dovetailed drawer before, and there are 6 of them in it...)
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"toller" wrote in message

Sorry, I am not sure I understand you ... the first eight words seem to contradict the rest of the concept?
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Why not screw the shelf to the two legs, and put a support under the shelf, attached to the legs in mortises; attaching the the shelf to the support with the slotted holes?
The shelf, with grain the same as the sides and top can be screwed between the legs. The support, with grain perpendicular to everything else, mortised into the legs. And screw the shelf to the support with slotted holes' though they could probably be left out.
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"toller" wrote in message ...

We're talking solid wood here, not laminate or veneer, right?
Why? You already know that solid wood of that width needs room to expand and contract with seasonal changes.
A design which calls for "screwing the shelf to the legs", unless I am missing something in your description, does not appear to be taking the dimensional instability of the solid wood into account.
As a furniture maker, you do that at your eventual peril.

A better way, as in the posted picture link, is to attach the shelf support to the rail between the legs, leaving room for the shelf between the legs to expand and contract. This also has the subjective benefit of hiding the end grain of the shelf and giving a seamless look to the joinery.
Alternately, if the design calls for the shelf to be supported by the rails, and the shelf is solid wood, you would be better off not "screwing the shelf to the legs" in any manner, instead leaving space for expansion and contraction of the solid wood shelf that you already know is a distinct possbility. Just incorporate that space into your design, and be sure to "join" the shelf to the rail with joinery that takes wood movement, and the cross-grain, into account.
One way to pick up on time tested methods is to study the construction of antique furniture. You will notice that the many antiques still in use have similiar joinery methods ... with good reason.
Forget today's "commercially" made furniture, regardless of its "quality" ... a good bet is that much of it won't be around in 100 years, and it is doubtful that most of it is actually "solid wood", despite its appearance.
You will be far better off learning what you can from those pieces which have stood the test of time.
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... snip

In today's vernacular, "solid wood" often means plywood plus a few pieces of hardwood face-frames. Kind of a different meaning to "solid" wood than most of us would use.

+--------------------------------------------------------------------------------+ If you're gonna be dumb, you better be tough +--------------------------------------------------------------------------------+
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"Mark & Juanita" wrote in message

Everyone in this conversation is well aware of the distinction, thanks.
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for an explanation.
The two legs are held together by: 1) the top, which is parallel to the leg grain (pocket screwed, glue?) 2) the side panels, parallel to the leg grain (glued) 3) the shelf, parallel to the leg grain (pocket screwed)
Presumably the top, side panels, shelf, and legs all expand pretty much the same rate; so there is no relative movement. The legs are quarter sawn, but they are small and on the outside, so that shouldn't matter.
The problem that prompted the whole thread is 4) the cross grain support (loosely pocket screwed). I understand the support should have been done better; presumably mortised to the legs. But what difference does it make whether the shelf is screwed to the legs or not? The danger is that the shelf (and the legs and top) will expand and stress the screws holding the support. The shelf will not expand any more,or stress the support anymore, just because it is screwed. That would not be true if this were August, since then I would have exactly the opposite problem; but is it January.
(Thinking about it now, I could probably have avoided the problem by simply making the shelf 1/16" narrower everything else. Does that make sense?)
So, where is the wood movement that I am not considering? (I haven't put the top on yet, and am undecided about gluing it.)
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the orientation of the annual rings and the characteristic direction of movement. Your top and or shelf are going to do some cupping and making ugly unless you change you design. Not to mention - again - the instability of a pocket screw leg into a plank.
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is firmly attached to the body on all four sides. If it cups, then anything can. I am familiar with alternating ring direction to avoid cupping. Interestingly, a book I just read (returned it to the library today) says that you should have all the rings oriented the same so that the grain across the panel matchs better than it would if you alternated. He didn't think alternating rings gained any stability.
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avoid is cumulative errors resulting in one big bow. Not so, of course. Geometry doesn't work like that. Match heart to heart, sap to sapwood for best display, and if you're just screwing the two sides of the top, which is what the message implied, you have an unsecured middle which will choose its own way.
Out of curiosity, have you studied any basic woodworking texts? Are you working from any sort of plan?
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"why should the top cup? It is firmly attached to the body on all four sides" That implies it just screwing two sides of the top with an unsecured middle?

Have I studied any basic woodworking texts? Am I working from any sort of plan?
If you were trying to be helpful before, I appreciate that; but now you are just randomly argumentative.
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"toller" wrote in message

Using a more conventional method of table construction I would say that would be one way to deal with it ... but since the shelf is apparently what is holding the legs together?

From what you've described thus far, you might want to consider floating the top.
BTW, went to look at the picture again to try and better answer your questions, but it appears to have been removed.
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Primarily the sides are holding the legs together, though the top could probably adequate also. Was my 1,2, 3 ambiguous?
The shelf adds a little rigidity probably, but the legs couldn't possibly come apart if the shelf were removed.

aprons have parallel grain. Why would I want to float it? With all the grain running the same, why would anything move?

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"toller" wrote in message

You said your were going to glue the top on? Regardless of the underlying grain direction, that is generally not a good solution.
Have you heard of "figure eight fasteners" for attaching wood table tops? Check'em out.
http://www.woodworkersshop.com/Figure_8_Table_Top_Fasteners.htm
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this question. If the grain runs the same as the top on all 4 sides (and all the wood is butternut, bought at the same time, and stored together for several weeks); what is going to move? It is no different than a glued up board, or any other matched grain joint, is it?
If I am missing something, I would sincerely appreciate having it pointed out. I probably won't glue because it will be messy and I don't think it is necessary, but I can't see why it would hurt.
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