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Forum topic by Wingstress posted 05-27-2014 11:33 PM 666 views 0 times favorited 3 replies Add to Favorites Watch
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Wingstress

335 posts in 2974 days


05-27-2014 11:33 PM

Topic tags/keywords: question

Ok so I’m going to make a large cherry breadboard table with walnut ends. The cherry center sections are going to be about 7feet long and the bread board ends will be about a foot wide. Because the breadboards are so large the legs will be supporting the table via the breadboard. So I’m worried about the excessive moment I’ll be exerting on the tongue and groove. The stock is 1 inch thick but I haven’t joined and planed. I don’t know the shear stength of cherry so I’m considering reenforcing the joint with a steel plate. It is a dinning room table so I’m not expecting a huge load on it and because the bread boards are supported by the legs I’m not worried about someone using the end of the table to stand up. I’m just worried about someone putting full force in the center of the table.

So is there a proportion or rule of thumb for the moment exerted on a tounge and groove? Is a steel plate necessary?

Thanks

-- Tom, Simsbury, CT


3 replies so far

View PeteMoss's profile

PeteMoss

207 posts in 2930 days


#1 posted 05-28-2014 04:01 AM

I would think that since you have a foot of breadboard to work with, if you used some long tenons to connect the breadboard to the table, then it should be able to handle a lot of weight. Though unless it really messed up the aesthetics I would consider placing the load bearing structure (legs, aprons, whatever) under the body of the table.

-- "Never measure......cut as many times as necessary." - PeteMoss

View wseand's profile

wseand

2754 posts in 2501 days


#2 posted 05-28-2014 06:43 AM

I agree with Pete. I would bring the legs in and use a apron and corner bracing to support the ends. You may have a bit of a movement issue with that much of aa taable..

-- Bill - "Freedom flies in your heart like an Eagle" Audie Murphy

View jdh122's profile

jdh122

879 posts in 2277 days


#3 posted 05-28-2014 10:27 AM

Seems to me that even with long tenons into mortise (or a long tongue into as deep groove), there’s still potentially a lot of weight to be borne by only a third of an inch of wood (the thickness of the tenon). Not sure also about the steel plate idea. It would look pretty awful to have a steel plate simply attached under the table, with screws (in slots rather than holes in the plate, at least into the cherry).
If the table does not have aprons I would not do it the way you suggest, but with aprons any weight exerted in the middle of the table should mostly get transferred to the legs directly without being exerted on the bb ends.
But others know more about design than I do…

-- Jeremy, in the Acadian forests

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