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Forum topic by spunwood posted 744 days ago 1296 views 0 times favorited 18 replies Add to Favorites Watch
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spunwood

1193 posts in 1433 days


744 days ago

Topic tags/keywords: question

Here is my rough design:

It is a reclaimed glued up poplar coffee table. Laminated with 2” x 1.5” x 60” boards. It measures”
2×27x60

I have two questions, both dealing with design and wood expansion:

1. Why doesn’t a board and batten design cause problems?
I ask becasue I want to do a similair deisgn for the coffee table I am building.

2. If I want to through mortise the legs into a table top, how might I attach the apron?

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν


18 replies so far

View Roger's profile

Roger

14098 posts in 1401 days


#1 posted 744 days ago

Very interesting questions. I’ll follow along to see some answers myself. and thnx in advance to whomever comes up with the right ones.. :)

-- Roger from KY. Work/Play/Travel Safe. Kentuk55@bellsouth.net

View Lee Barker's profile

Lee Barker

2163 posts in 1448 days


#2 posted 744 days ago

I’ll wander into the arena here, fearless.

The board and batten examples you offer are likely nailed only, not glued. Nails shift, holes enlarge as the lateral dimension comes and goes.

(sidebar: note in the upper pictures the diagonals are properly installed, in compression. About a third of the ones you see these days are wrong, the opposite. Thanks for listening.)

The answer to number two: You don’t need a skirt if you’re attaching the legs that way. As I envision it, the skirt would look out of place. But perhaps you can come up with a design that pleases you that incorporates both.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

View bondogaposis's profile

bondogaposis

2439 posts in 948 days


#3 posted 744 days ago

Most people don’t want the large gaps you see in the barn door examples in their living room furniture.The board a batten doors are usually tongue and groove and nailed on one edge only allowing the wood to move. It certainly would work the same for a table, but it would be considered “rustic” or “country”. If that is the look you want their is no reason it wouldn’t work.

-- Bondo Gaposis

View Dan Krager's profile

Dan Krager

1465 posts in 831 days


#4 posted 744 days ago

Bondo is right about the gaps. Even if you put tongues into grooves, you will still have gaps that gather debris and change with the weather. T&G is good for siding and doors to keep more of the weather out, but not so much in surfaces. BTW, the nails were put through the tongues diagonally right next to the root of the tongue. The nails were hidden, and the tongue held the groove edge of the next board down. You won’t see that done with boards over 8” wide.
A solid glued up top is most common because it works. I use relatively narrow widths (3” max) to glue up for several reasons. You can use cheaper lumber and it tends to be more stable. You can still use battens underside IF you allow for movement while holding flat. RH screws washered and placed in long grain slots in the batten getting longer from center out work well. Different woods move different amounts: Cherry and Poplar are quite stable once dried. There are charts available for amount of movement for different woods. You can always cut a shallow v groove on the glue joint to simulate T&G.
A top can be securely fastened to an apron in a way that allows movement. Dado a 1/4×1/4 groove on the inside of the apron about 1/4 down from top. Fasten the top with “buttons”, a small block with a 1/4×1/4 tongue about 3/16” off one side. Stick the tongue in the groove and screw into the top, drawing it tight to the apron at about 18” intervals.
I agree with Lee that through M&T leg posts are generally incompatible with aprons, from both practical and aesthetic views. The through M&T assumes a very thick top capable of holding its own between the legs without the support of an apron. Personally, I wouldn’t use M&T in a “thin” (anything less than 2”) glued up top for risk reasons. Sure as I do, some 400 lb gorilla will plop down and split the top. You might increase chances of success with solo M&T by putting a bread board cap on each end on stuff less than 2”.
You can always inlay a thin piece to simulate the appearance of a through M&T.
Dan

-- Dan Krager, Olney IL http://www.kragerwoodworking.weebly.com

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Dan Krager

1465 posts in 831 days


#5 posted 744 days ago

I looked again at your design when this popped up in another place. Those cross pieces are the nemesis to work around. You could carefully cut large french dovetails to hold them in place like large breadboards. I see the point of the apron now, to lend support to the weakness caused by the cross pieces.
Good luck.

-- Dan Krager, Olney IL http://www.kragerwoodworking.weebly.com

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spunwood

1193 posts in 1433 days


#6 posted 744 days ago

Wow, really helpful stuff guys. I guess I will have to think about which design elements I am most attached to.

Lee: Great explanation of the board and batten. Amazing how practical something so old like that is.

Bondo: Good point. I see that the rustic look which works for a door will not keep the crumbs and dirt out of a table which the kiddos and myself will surely accumulate.

Dan: I really like the idea of a Sliding dovetail.

This will take some more thought.
Brandon

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν

View CharlieM1958's profile

CharlieM1958

15653 posts in 2815 days


#7 posted 744 days ago

! agree with what has already been said, but I’ll add this regarding an apron: If the legs are through-mortised to the top, I don’t see any way you can attach an apron to the legs. The movement of the top will cause the legs to pull away from the apron. You could install the apron in the usual way, with mortises, but just not glue the joints. That would allow the legs to move, but might result in some visible gaps at the joints.

-- Charlie M. "Woodworking - patience = firewood"

View Dan Krager's profile

Dan Krager

1465 posts in 831 days


#8 posted 744 days ago

The leg pair on the long grain won’t be the problem. The cross grain pair will be. You have a good solution, Charlie.

If you go with apron, consider strongly the option of traditional M&T and button top attachment for the apron leg assembly and use inlaid patches that look like through M&T on the top. Avoids (almost) all the problems.
Dan

-- Dan Krager, Olney IL http://www.kragerwoodworking.weebly.com

View Greg The Cajun Box Sculptor's profile

Greg The Cajun Box Sculptor

4932 posts in 1906 days


#9 posted 744 days ago

You could lower the aprons down by an amount equal to the thickness of the top and fasten them to the legs. Afterwards fit them into the matching mortises in the top.

-- Every step of each project is considered my masterpiece because I want the finished product to reflect the quality of my work.

View Boxguy's profile

Boxguy

1408 posts in 865 days


#10 posted 743 days ago

I would think of this as two separate units… top and legs. Let the top float, and it will work out its own movement problems. Glue it up and go on to the legs.

The legs should be able to stand on their own without help from the top. The reliance of the legs on the top seems to be the main obstacle in your design. There are any number of mechanical or joint connections for table legs. Most involve a 45 degree board or metal fastener connecting the two aprons and the leg at the corners.

These are short legs, but they should still have a wide enough apron to give them good support. You might look at my post in the “box” section called “Boxguy Lowers The Water Table” for a take on having your legs look more like they are floating and eliminating most of the apron look…just a thought.

How do you connect the top and the legs? It could be as simple as a dowel in top of the legs fitting into an over sized, unglued hole on the underside of the top, or you could use fasteners that slide along a groove. This top will be heavy and coming off accidentally should not be a big problem.

Settle for the illusion of a through mortise. Once the top is not needed to hold the legs, your problems are solved. You can arch, round over, and notch the stretchers to give it more the look I see you going for.

I appreciate the elegance of having the top hold the legs, but there are significant problems in the nature of wood that work against that design element.

Well, that is my two-cents worth. It is an interesting problem in design. Good luck on your project.

-- Big Al in IN

View casual1carpenter's profile

casual1carpenter

353 posts in 1073 days


#11 posted 743 days ago

just a note on shrinkage, a while back someone posted a link to “shrinkulator” it is supposed to give expansion contraction data. I do remember that i found results interesting.

View spunwood's profile

spunwood

1193 posts in 1433 days


#12 posted 743 days ago

Well, what it comes down to is my need to personalize a simple project…so:

I went with floating the top and attaching an apron to the legs and the leg/apron component with table top fastners. I did however use french cleats to accent the top.

I decided not to make the fake mortises, just more work and I am not a big fan of illusion.

Thanks for your help guys. I will surely post here when the project is done.

-- I came, I was conquered, I was born again. ἵνα ὦσιν ἓν

View carguy460's profile

carguy460

774 posts in 933 days


#13 posted 743 days ago

Uh oh…dumb question about to come out of my mouth…

Lee – when you say that in the first picture, the diagonals are correct, “in compression”...what do you mean? can you point me to an example of a wrong one?? I’m not sure I understand…

Thanks in advance!

-- Jason K

View Dallas's profile

Dallas

2854 posts in 1084 days


#14 posted 743 days ago

Jason, I think Lee meant that the diagonal is pointed from the outside at the top aimed toward the hinge side at the bottom.
That compresses the wood by gravity and weight, making the gate/door stronger.

If you try to put the upper part of the diagonal at the hinge and hang it outward toward the bottom, the stress in in extension and will pull apart from the weight and gravity over time.

-- Improvise.... Adapt...... Overcome!

View carguy460's profile

carguy460

774 posts in 933 days


#15 posted 743 days ago

Thanks Dallas…that makes perfect sense to me now, and made me realize that I would have done it backwards!

-- Jason K

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