Bent Lamination strength

[James Jayko]

A friend of mine was talking about building a bed based on a design he saw online. The top of the footboard / legs at the foot of the bed were what looked like one curved piece of wood. Which made me wonder...would bent laminations (Unibond 800) be strong enough for that type of force on a bed? I would guess the bend was like a 12-14" radius, so fairly tight. If you glued up 10 1/8" pieces to get to a finished 1 1/4" dimension, is the glued up piece as strong (or at least strong enough for use in this application) as a 1 1/4" solid piece? Am I overthinking this?

[Edward Weber]

10 1/8" layers laminated into a 1 1/4" thick, regardless of shape, is many times stronger than solid wood of the same size.

[John TenEyck]

^^^^^

It's the same reason LVL beams have much higher load capacity than comparable solid wood ones.

John

[Robert Engel]

It also depends on what it's supporting and forces.

You use your own imagination.

[Andrew Hughes]

I’m thinking what woods would let you bend into 12/14 radius. At 1/8 thick it’s going to be difficult the as the radius gets tighter the thinner the strips need to be or tapered in thickness.
If you don’t believe me check it out.

[James Jayko]

I’m thinking what woods would let you bend into 12/14 radius. At 1/8 thick it’s going to be difficult the as the radius gets tighter the thinner the strips need to be or tapered in thickness.
If you don’t believe me check it out.

No reason not to believe you! But it is surprising that 1/8" won't make a 12" radius.

[Edward Weber]

No reason not to believe you! But it is surprising that 1/8" won't make a 12" radius.

12" radius is tight if the wood is dry, add some heat and/or steam and it's not an issue at all.

[Andrew Hughes]

No reason not to believe you! But it is surprising that 1/8" won't make a 12" radius.

I should have been more clear. Depends on where the radius is on the inside or the outside. Inside radius of 12 inch will grow proportionately greater. My guess 14 inches at the outside.
And visa versa.
If you have done any bend lamination it’s a fantastic and challenging task. Everything from building a form that works to glue up. Cutting the lamination all requires special attention.

[James Jayko]

If you have done any bend lamination it’s a fantastic and challenging task. Everything from building a form that works to glue up. Cutting the lamination all requires special attention.

I've done it for some minor curves on arms for a morris chair. It was a good learning experience.

[Robert Engel]

A drum sander is nice to have for laminations. 1/8" is never going to bend that sharp. Even 3/32.

For a 12-14" radius, I'd be looking at thick veneer (1/16") I can almost get there with my drum sander.

With steam you might do it. Gonna be a lot of tension when it dries.

[Mike Rambour]

bent laminations is what was recommended to me a few days ago here on this forum for a chair I am building. Working on the forms now as yes it is stronger.

[Edward Weber]

Keep in mind that every species has different properties, the OP didn't mention a species that I saw.

[Zachary Hoyt]

I routinely bend 3/32" thick guitar sides to a 2" radius using a piece of copper pipe and a propane torch. 1/8" is doable but much harder. 12-14" radius is 24-28" diameter, the size of a large garbage can.

[Kevin Jenness]

10 1/8" layers laminated into a 1 1/4" thick, regardless of shape, is many times stronger than solid wood of the same size.

I would like to see some documentation for that statement. Gluelams and the like may have higher strength values than solid timber of the same grade due to knots and other defects being randomly distributed, but if you tested a clear, straight-grained piece of lumber against a laminated piece of the same dimension I think you would find the results pretty similar. Bent laminations are a different situation compared to a curve cut out of the solid with cross grain and short grain.

[mreza Salav]

A drum sander is nice to have for laminations. 1/8" is never going to bend that sharp. Even 3/32.

For a 12-14" radius, I'd be looking at thick veneer (1/16") I can almost get there with my drum sander.

With steam you might do it. Gonna be a lot of tension when it dries.

1/8 easily bends around a 12" radius, no problem without steam even.