Creating a Heavy Laminated Furniture Frame
A furniture maker gets tips on wood bending and lamination for a four-by-four curved hammock-chair frame. May 23, 2007
We would like to produce a hammock chair stand, and feel that a bent lamination method might work for us. We have produced two forms (one male, one female) to be used as a press. The radius of the curve to be produced is 27'' inside, 31" outside. To eliminate as much of the trial and error as possible, I've read every thread on bending and laminating on this site. I'm still somewhat confused. If I use laminating strips of 1/4" in thickness x 4" in width, will I need to steam, bend, dry and finally laminate? Or will that thickness bend to my radius without steam? Perhaps a thinner thickness would work better? Should I use dry wood or green? Finally, with regard to lumber selection, I would like to use oak as it appears to be a good choice for bending, has a nice appearance when finished, and is strong (stand will need to hold 250 lbs). Is there a particular grade of lumber I need specify? And is there an industry term for surfaced laminating strips?
(Furniture Making Forum)
From contributor J:
Run some tests - if the unsteamed pieces bend without breaking, then steaming isn't necessary. If they break, then try using thinner pieces. If the radius is very tight and the laminations are as thin as you wish to saw them, and they still break, then steaming may be required.
Ash and oak are good bending woods. The wood should be dry. If you use green wood, it will dry eventually, and the results will be uncontrolled. If the joint is stressed and the wood has drying defects in it, then there could be some strength issues.
From contributor K:
That sounds like a vacuum bagging job to me. I have not used a two part form since learning it about 20 years ago. I would drop on down to 3/16", and use a thickened epoxy, then slip them into a bag. Use only enough clamps to hold the parts to the form, then draw the vacuum. Spread some epoxy onto a scrap to monitor how long it takes to kick by feel.
From contributor B:
How thick is your final product after glue up? If it is 3/4", then 1/4" thick strips will only allow 3 strips. This won't be enough to even begin to prevent springback without a pre-steam bending step.
From contributor C:
If I follow correctly, these arcs will be sections of a circle with sixteen plies and be about 4" by 4". If this is right, your forms or cauls should be very heavily built to withstand a lot of bar clamps without coming apart or deforming. With this type of laminate, it should not be necessary to steam the boards. How much of a circle are these pieces when done?
From contributor B:
I should have read your post a second time. It does seem you indicate a 4" final part thickness. Our experience with thick laminations is that they tend to spring in versus out. This is probably due to the absorption of moisture from water based glues on thinner strips. I would suggest 1/4" strips and think you should be able to do this without pre-steam bending the parts. At 4" final thickness, you should get almost no springback.