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Thread: Wood movement on outdoor table

  1. #1

    Question Wood movement on outdoor table

    I'm building a 2-person (28" diameter) patio table from Sapele. My concern is attaching the pedestal body to the base. I'm thinking of doing double tenons, but I'm worried I'll have a wood movement problem between the pedestal and the base. Below are a couple screen shots to show what I'm talking about. I'd appreciate any suggestions on joining these together.

    Tenon Screenshot.pngPedistal Base.png

  2. #2
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    Maybe a sliding dovetail instead of the M&T - glued near the center, with some room to move outward?

  3. #3
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    I think the joint looks fine and easily accomplished.
    I would like to suggest a slight taper on the boards laying flat to keep water away from the mortise and tenons.
    Outdoor furniture cannot follow rules of indoor furniture.
    Good Luck
    Aj

  4. #4
    Quote Originally Posted by Andrew Hughes View Post
    I think the joint looks fine and easily accomplished.
    I would like to suggest a slight taper on the boards laying flat to keep water away from the mortise and tenons.
    Outdoor furniture cannot follow rules of indoor furniture.
    Good Luck
    Thanks. I do plan on putting some curves on the underside of those boards. I'll probably put leveling feet too.

  5. #5
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    If you make the vertical parts from plywood the expansion problem goes away.

    How will you attach to the top?

  6. #6
    Quote Originally Posted by Gary Ragatz View Post
    Maybe a sliding dovetail instead of the M&T - glued near the center, with some room to move outward?
    +1 on the sliding dovetail

  7. #7
    I'm using Sapele, I do not want to use plywood. It is quarter-sawn, so wood movement will be less than if it was flat-sawn. I'll use mortise and tenon for the top, but the tenons are only a few inches apart, so I'm less worried about that.

  8. #8
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    Your pedestal / top joint will be small. I'm imagining a heavy item plopped onto the top and breaking that joint. How about widening it out like the joint at the base but slim in the center. But then you will have the expansion problem top and bottom. Solve this by splitting the pedestal into 4 legs lightly joined halfway up and maybe showing a 1" gap top and bottom. This will add some interest to an otherwise plain piece.

    Sitting on the floor it will be damaged by moisture and may wobble if the floor is not perfectly flat. You can get really good rubber feet from McMaster Carr.
    Last edited by Tom Bender; 07-15-2022 at 8:47 AM.

  9. #9
    Attached are some sketches on my current thinking on the design. On both the top and bottom I have the wider spaced tenons on the wood that has the slot. I'm hoping this will allow some wood movement. I'm not going to glue the two pieces where they interlock, I'll just glue the joints at the top and bottom. The pedestal top pieces are 4-3/4" wide. This attaches to a disc that's 8" diameter, which will be screwed to my table top (28" diameter).

    I'm going to put leveling feet on the bottom to keep the wood off the deck and to prevent rocking.


    Pedestal 1.png Pedestal 2.png Pedestal 3.png

  10. #10
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    Quote Originally Posted by Scott Goldthwaite View Post
    Thanks. I do plan on putting some curves on the underside of those boards. I'll probably put leveling feet too.
    I think Andrew was suggesting putting a crown of some sort on the top​ of those boards, so that they would shed water rather than letting it sit where it might get into the joinery - a good idea, IMHO.

  11. #11
    Quote Originally Posted by Gary Ragatz View Post
    I think Andrew was suggesting putting a crown of some sort on the top​ of those boards, so that they would shed water rather than letting it sit where it might get into the joinery - a good idea, IMHO.
    Good idea. I'll do that.

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