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9 ft table with 7 inch breadboards question

1225 Views 12 Replies 9 Participants Last post by AlaskaGuy, Dec 12, 2020

Lrobinson

Discussion Starter · Dec 6, 2020 (Edited by Moderator)

Thanks in advance for any and all advice. I'm building an 9ft long x 42'' wide dining table with 8/4 pine. The longest boards that I can salvage after milling is 8ft. So my plan is to have 6" wide breadboards which would increase table length to 9ft. I will be using floating tenons. The tenons will be roughly 3/4" thick and will go into the breadboard roughly 2". I realize that this is about an inch short of the suggested minimum of 1/2 the width of the breadboard. With that being said, I see a lot of slab builders use C-channel to add strength to their slabs. What If I were to add a C channel connecting the main table top to the breadboard to add more strength. Is that possible/beneficial?
I've attached some photos below to help. the first picture is of the whole table, and the second picture is an underside view of the c-channel idea.

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SMP

· #2 · Dec 6, 2020

Do you plan on having people sit at the ends? Is there a reason you don't want to do 3" tenons and have the table a couple inches shorter?

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bondogaposis

· #3 · Dec 6, 2020

A lot depends on how thick the table top is.

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wapakfred

· #4 · Dec 6, 2020 (Edited by Moderator)

It's certainly possible…I'm wondering about the "beneficial". My concern is how the c channel would be fastened to the table top and the breadboard ends. It will need to be secure. So call the channel 3/4" thick. I'm guessing the 8/4 pine finished to 1 3/4" thick (?), and you cut a 3/4" groove for the channel. That only leaves 1" of pine for the screws to bite into.It might be a lot more rigid if you extend the channel length by another foot or more, that would get it supported buy the leg set.

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Lrobinson

Discussion Starter · #5 · Dec 7, 2020

Thank you all for your advice.

To SMP: The plan is to have a full 9 ft table. Taking off 3 inches to make the tenons on each side would make the table down to 8.5 ft. This is why I'm probably doing loose tenons.

To bondogaposis: Top will be probably have a final thickness of 1 3/4" or 1 7/8'' after milling

To Fred: That's a good idea. Since the C-Channel will be flush with the bottom, I guess there's no reason I can't use a longer c-channel bar.

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avsmusic1

· #6 · Dec 7, 2020

what's the constraint causing the tenon length to be 2"? Length of router bit? Personally, I'd rather chisel out another 1" than add c channel to this type of design

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GrantA

· #7 · Dec 7, 2020 (Edited by Moderator)

You do realize that this is not the way to attach functional breadboards right? Your table boards can still cup. If you're going through the trouble of building it do a little more homework and cut the ends properly

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Lrobinson

Discussion Starter · #8 · Dec 7, 2020

You do realize that this is not the way to attach functional breadboards right? Your table boards can still cup. If you re going through the trouble of building it do a little more homework and cut the ends properly

- GrantA

Grant, Thank you so much for your completely unhelpful comment. I'm not quite sure why you thought it necessary to reply at all honestly. Also, what exactly is wrong with attaching "functional" breadboards with loose tenon joinery? Are you of the belief that the breadboard MUST have a groove in it? If so, then you need to do your own homework. I've made many tables using loose tenons in the breadboard. One of those tables has been sitting in my mother's dining room for almost 15 years with zero issues.
The center tenon is still the only tenon that gets glue. The center mortise in the breadboard is the only "tight" fit. The rest of the mortises are anywhere between 1/8'' and 1/4'' oversized in order to allow for wood movement. These are also not glued. Then holes are drilled through the top into each tenon where dowels are driven through.

So, once again, what exactly is wrong with what I'm doing.

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AlaskaGuy

· #9 · Dec 7, 2020

Nothing wrong with loose tenon bread board ends.

I do prefer to combine the loose tenons with a small tongue and grove though.

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pintodeluxe

· #10 · Dec 7, 2020 (Edited by Moderator)

I have a love hate relationship with breadboard ends. They're a lot of work to do right, but I like the aesthetics.

I really don't think you should use the breadboard ends to make the table longer. Decide how wide they should be, based on the joinery you're using.

If your pine is only 8', just make a slightly shorter table than planned. Myself, I wouldn't do breadboards wider than 3-1/2". And that would be with a 2" long integral tenon in my case.

Also, I can't imagine a room that a 9' table would work well in. A shorter design would be easier to move, and easier to decorate a room around.

Shorter table, narrower breadboards would be my vote. I like the base design by the way.

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Lazyman

· #11 · Dec 7, 2020

I have to say that I too was concerned that you were just gluing loose tenons in to attach the bread board. You didn't exactly elaborate in the OP. When you say that there is no glue except on the center tenon does that mean that you use 2 dowels per tenon on the others, one in the table and one in the breadboard? It seems like they should all be glued into the table and loose on the bread board (or vice versa).

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GrantA

· #12 · Dec 8, 2020 (Edited by Moderator)

Well, since it sounded like you were planning to use tubafours with dominoes and were considering adding steel to strengthen it up I called it as I saw it. I have seen worse- pocket screwed (hard) breadboards on tabletops at a local restaurant from a local "woodworker"

So, I apologize, but unless you're using narrow boards (nothing wrong with that either) or putting multiple tenons on the boards (which both sound like extra work) a traditional breadboard joint will better resist cupping. Plus then your tenons are 8ft long ;-) ever seen a breadboard sagging down? I have.

And like Nathan said, I'd think gluing them all into the table would be the way to go then let the ends have dowels.

Good luck whichever way you go.