How to bend wood like this - Outdoor furniture project

[Alan Lightstone]

I think I would have done far better with air dried white oak, but couldn't get it from my local supplier. That led me down a path that despite tremendous effort, just won't work for me. It's going to be solid wood.

I understand that the joints will be miters. I wrote that badly. If I have to veneer over the outside of the pieces to make it look better, I certainly can do that. Might have to buy a slightly larger vacuum bag, but really don't know if I'll need to go that route.

That's an interesting insight, Kevin, regarding long router bit chatter. I do have a good bandsaw, and a good Hammer oscillating edge sander, so I should be able to sand things reasonably well after gluing, although have to make an extension of sorts to keep the curved piece level when sanding. Sanding the inside of the curve might be a little more challenging.

[Maurice Mcmurry]

Green wood bends the best. For my "tree to finished product" projects I have done the bending with wood that is not even air dried.

[Mike King]

Not necessarily. Pneumatic pressure is an option (Fine Woodworking #63 p. 83, Pneumatic Lamination). If one runs short of clamps threaded rod is an alternative as shown here. https://woodarchivist.com/3725-makin...nation-curves/ In any event the project needs enough force distributed evenly through cauls to pull the laminates together gap-free.

Pneumatic pressure is effectively more clamps. And potentially dangerous, as said well above.

[Mike King]

I think I would have done far better with air dried white oak, but couldn't get it from my local supplier. That led me down a path that despite tremendous effort, just won't work for me. It's going to be solid wood.

I understand that the joints will be miters. I wrote that badly. If I have to veneer over the outside of the pieces to make it look better, I certainly can do that. Might have to buy a slightly larger vacuum bag, but really don't know if I'll need to go that route.

That's an interesting insight, Kevin, regarding long router bit chatter. I do have a good bandsaw, and a good Hammer oscillating edge sander, so I should be able to sand things reasonably well after gluing, although have to make an extension of sorts to keep the curved piece level when sanding. Sanding the inside of the curve might be a little more challenging.

Kiln dried lumber is not an issue with bent lamination. You need 1) laminates that are thin enough to be able to bend around your form, 2) an appropriate glue that has a hard glue line (and likely sufficient working time), and 3) sufficient pressure distributed over the laminates to bend the laminates gap free around your form. I've constructed a number of chairs using both steam bending and bent lamination techniques with kiln dried wood.

I gather that you also tried steam bending. A few questions about that:

1. Did you soak the wood? When I bent 10/4 kiln dried cherry, I soaked the blanks for 7 days before steam bending them.
2. Did you wrap the blanks in plastic when you steamed them? This is a technique I learned from Michael Fortune. Wrapping the blanks in plastic helps to retain moisture in the blank as you steam it and increases heat transfer to the blank.
3. How long did you steam the blanks? I'm at 5400 feet so I can't get my steam box above 197 degrees. As a result, I steamed the 10/4 blanks for 4 hours to ensure that they were very well heated. I've also bent 9/4 kiln dried walnut at 8200 feet -- sufficient time soaking to raise the moisture content of the blank and sufficient time in the box to heat the lignon is needed to be successful in bending.
4. Did you use a strong compression strap? Steamed wood will compress considerably, but if a compression strap doesn't tightly hold the inside of the stock, the blank can separate or crack. The Veritas compression strap and fixtures (from Lee Valley) are very good--they were designed by Michael Fortune, and come with a guide to steam bending that was written by him.
5. Did you put your bent parts on a drying form? Once bent, the part needs to be clamped to a drying form to dry. It takes 1 to two weeks for the part to return to equilibrium moisture if it has been properly steamed. Removing the part from the drying form generally leads to a minimum of excess springback or, for that matter, the part looking nothing like the form.

Mike