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Thread: Trestle table with a large slab top

  1. #1

    Trestle table with a large slab top

    I've got a pair of bookmatched walnut slabs, 2.5" thick and when joined together ~52" wide in the middle, 48" or so at either end. I'm hoping to put on a trestle style base but am confused as to how big the post needs to be to support a top this wide. An old FWW article indicated that past 36" wide you'd need two posts on each end. I don't love the way this looks, have been playing with a design that includes two 3x4" posts with a 2x2" panel resting loosely in a groove between them. The stretcher would fit into this panel, giving the look of a single wide post with some depth to it. Would this be sufficient, or do the posts need to be further apart to fully support table?

    table-dimensions.jpgtable-side.jpg

  2. #2
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    Structurally, you'd be okay with a "post" which is 7.8" wide. But as I look at your drawing, 7.8" looks too skinny compared to the massive top. This is just an esthetic judgement -- your taste may be different from mine. I'd try a "post" which is more like 12"-14" wide. Your approach of larger timber at the edges would work, but you might look at a post which is 1.5"-2" thick throughout.

    Also, there's no structural reason for the foot of the trestle to be as wide as you show. It can be narrower, so people's feet don't trip on it as much. The table top weighs so much that the table will not feel tippy even if the foot is 32".

  3. #3
    Thanks for the feedback, playing now with a post that is 2" thick like the foot. Still playing with the idea of a panel between two posts just to add a bit of depth, and took your suggestion of going to 12" wide (but tapering to 10" at the top). Liking this so far.

    table-wide-tapered-panel.jpg

  4. #4
    What does your design look like under the table? Also how is your stretcher connecting to your posts.

  5. #5
    Was going to build a grid like structure with 2 or 3 2x3 stretchers going most of the length and 4 or 5 battens going across. Stretcher would be a wedged tenon, glued in to post

  6. #6
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    Quote Originally Posted by Joseph Sullivan View Post
    Was going to build a grid like structure with 2 or 3 2x3 stretchers going most of the length and 4 or 5 battens going across. Stretcher would be a wedged tenon, glued in to post
    You don't need a grid like that. The top is 2.5" thick of solid walnut. It is way stronger than the grid. The top of each trestle should be a crossbar somewhat like you've drawn the foot. That's all you need.

    When you fasten the top of the trestle to the table top, you should allow for the top's expansion and contraction across the grain. You fasten the top to the trestle firmly in the middle, but use a sliding joint near the ends of the crossbar.

    The stretcher (which maybe is what you're calling a panel?) would benefit from being taller than you've drawn. Structurally, it is the part which prevents the table from racking end-to-end. More height gives in more anti-racking resistance. I'd make it 6-8" tall. It only needs to be 3/4" thick, but if you want to make it beefier you can. You also can put it higher on the legs; it will provide the same anti-racking force as if it is lower down, and it will be less likely to whack shins.

  7. #7
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    That table top is so heavy it counterbalances any vertical forces on the table edge. As I run the numbers on your design, if the trestle foot is 24" wide, a 280 pound person could sit on the edge of the table top -- without his feet touching the floor -- and the table would not tip over. I good thing about the narrow foot is that sitters' feet will not trip on the foot, no matter where they sit, and chairs can easily be stowed under the table.

  8. #8
    Thanks for the feedback, Ill go with a simpler top structure and will play with the leg width.

    Quote Originally Posted by Jamie Buxton View Post
    When you fasten the top of the trestle to the table top, you should allow for the top's expansion and contraction across the grain. You fasten the top to the trestle firmly in the middle, but use a sliding joint near the ends of the crossbar.
    I was planning to do elongated holes in the base and screws into threaded inserts in the top. Since there will be a 10 post right in the middle, what is the best way to attach that part? Zclips/ buttons, nothing at all, something else?

  9. #9
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    Quote Originally Posted by Joseph Sullivan View Post
    Thanks for the feedback, I’ll go with a simpler top structure and will play with the leg width. I was planning to do elongated holes in the base and screws into threaded inserts in the top. Since there will be a 10” post right in the middle, what is the best way to attach that part? Zclips/ buttons, nothing at all, something else?
    One possibility would be to glue a block -- maybe 2x2x6 -- on the inside face of the crossbar at the middle. You bolt up though it into your threaded insert in the top.

  10. #10
    Shaker trestle design is about as elegant it gets (structurally). The key is the top center stretcher. If done wide enough if will add all the racking stability you need. It also stays largely hidden from view, so it does not appear bulky. Last, each half of the table acts as ballast to the other, so the cross members only need stretcher support in the center.

    As for attachment, I made these. Perhaps overkill, but they work ok. They screw into the top of the cross members with elongated slots. They fit into recesses in the bottom of the panels. The recesses are oversized only to make alignment easier. Don't be confused by the iron u channel. That's there for extension leaf support.

    block.jpg

    block2.jpg
    Last edited by Prashun Patel; 11-29-2021 at 8:11 AM.

  11. #11
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    I used to build a few trestle tables and have one now in the dinning room. I make the legs and the cross member at the top the same size. The most important structural component is the joint between the foot and the uprights (ends) and the cross member at the top and the upright. That is were a tremendous amount of stress occurs when your wife climes up on the side of the table top to replace a light bulb in the chandelier over the table!!!BFT.jpg
    Ask a woodworker to "make your bed" and he/she makes a bed.

  12. #12
    Thanks for all the helpful info all! The last bit Im puzzling over is how best to attach the legs to bottom foot / top support. The leg will be 10 at the bottom and 8 at the top, was going to do two split tenons around 2.5-3 wide, but given the width of leg how worried do I need to be about movement? Should I glue a single tenon and just peg the other to allow some float? Split to 3 tenons and glue the middle one? Not worry about it?

    Edit: the other thing Ive considered is a floating panel between the two legs, with the legs and foot/ top support acting as a frame around this center panel. That would allow the legs to move as separate 5 pieces, but Im not sure about the strength of stretcher through this floating panel. Am I overthinking this?
    Last edited by Joseph Sullivan; 12-01-2021 at 2:18 PM.

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