Cantilevered Bases?

onocoffee

onocoffee

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I’m finally getting round to building the bases for another countertop. Originally, I was going to go with a simple T-style base but lately I’ve been thinking about making it cantilevered a bit with some curvature for flourish.

I’ve included my crude illustrations of the base that will be made out of 1.5” thick cherry. It will be for an L-shaped padauk countertop that’s 82.5” and 80.25” that’s 17” deep (more or less in both directions.

I’m planning on making the base with two legs that are connected with stretchers and then the third leg on the shorter end just running solo.

Any thoughts or considerations I should think about before beginning? Thanks!
 

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Some examples from online. Might give you some inspiration:


I’ve seen cantilevered construction that used a steel plate in which might be called a steel reinforced bridal joint.

A conventional bridal joint is shown below:

1765053218269.gif

Instead of having one open mortise and one tenon and gluing, the example I saw had both pieces as open mortises to accommodate about 1/8” tenons. And instead of wood tenons, it had a still plate; that was cross drilled and pinned with what looked like wood pegs, but I suspect they hid a steel threaded fastener.

In any event, a cantilever is asking an awful lot of strength from a single joint. I have no way to estimate the strength requirements of a cantilever joint. Conventional joints have stresses in compression and tension and some stresses in racking (side-to-side movement). But the cantilever joint is all about that racking strength. If I had to guess, a cantilever joint would have to be stronger in excess of 4 times the racking strength of a conventional joint.

Diagonal braces, and inside angle gussets will add strength to the joint.

I think the best-known example of a cantilever designed piece of furniture is the Breuer Chair (still in production at about $750.00 from Knoll).

1765054485745.jpg
 
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It might be worth mocking up the joint and seeing how much load it takes to break it. Kind of like what they do with aircraft wings. Static load testing on wings is often done with them upside down to enlist the help of gravity. Not sure what they were testing with the Hurricane, but it make me smile...

wingload-1.jpeg

wingload-2.jpeg
 
That top is going to be quite heavy. I'd suggest using an equally-substantial ledger board, screwed to the wall studs to support the weight of the top as well as anything that might be placed there. Perhaps some 1" x 4" angle brackets would help to keep the top aligned with the ledger board and keep the top from pulling away from the ledger board.
 
Packard said:
Some examples from online. Might give you some inspiration:


I’ve seen cantilevered construction that used a steel plate in which might be called a steel reinforced bridal joint.

A conventional bridal joint is shown below:

View attachment 379723

Instead of having one open mortise and one tenon and gluing, the example I saw had both pieces as open mortises to accommodate about 1/8” tenons. And instead of wood tenons, it had a still plate; that was cross drilled and pinned with what looked like wood pegs, but I suspect they hid a steel threaded fastener.

In any event, a cantilever is asking an awful lot of strength from a single joint. I have no way to estimate the strength requirements of a cantilever joint. Conventional joints have stresses in compression and tension and some stresses in racking (side-to-side movement). But the cantilever joint is all about that racking strength. If I had to guess, a cantilever joint would have to be stronger in excess of 4 times the racking strength of a conventional joint.

Diagonal braces, and inside angle gussets will add strength to the joint.

I think the best-known example of a cantilever designed piece of furniture is the Breuer Chair (still in production at about $750.00 from Knoll).

View attachment 379727
Click to expand...
How about that? Our dad had chairs identical to that as part of the dining table set. I can’t remember what the table was like.
 
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