Curved plywood panels for sleigh bed

[Richard Goodwin]

I am designing a queen sized sleigh bed and am considering making curved panels for the headboard and foot board by laminating 2 sheets of 1/4 inch plywood (total thickness of 1/2 inch). I would make up a former with the required curve, apply glue between the 2 sheets of ply and then clamp them into the formed shape. Hopefully when the glue is dry, the sheets will retain their curved shape. I would fit the panels into routed slots in the frame at both sides and top and bottom. Does anyone have any comments on my proposed method?

[johnny means]

Your 1/4" sheets are too stiff and will spring back when unclamped. I would use a bending ply or kerf board, then veneer. You could also lay up your own curved plywood, though it would be a lot of work.

[Jamie Buxton]

In the US we can get stuff called bending plywood. Dunno what it would be called in New Zealand. It is three-ply plywood, and the middle ply is much thinner than the usual plywood. This makes it very bendable in one direction, and very stiff in the other direction. It is ideal for the use you're planning. You'd laminate several layers of it over a bending form. The stuff I get here is called eighth inch, but is actually 2.5 mm. My supplier calls it Italian bending poplar.

[Richard Goodwin]

On reflection, I think you are right regarding the ply thickness. How do you feel I would go with 3 or 4 sheets of 1/8th inch ply? I don't think bending ply is available in NZ, but i will make enquiries. Thanks for your reply.

[Richard Goodwin]

I don't think bending ply is available her, but I will check.

[Jamie Buxton]

..How do you feel I would go with 3 or 4 sheets of 1/8th inch ply?...

If the radius is large, standard (ie not bending ply) plywood should be okay. And in general, making a bend with more laminates, rather than fewer, gives less springback.

[Richard Wolf]

If you can't find bending ply, you can make your own kerf ply. A series of saw kerfs into a sheet of 1/2" ply and laminate a heavy veneer on the kerf side.

[John T Barker]

If it is something you would consider I recall doing a search (before internet) for a source for the panels already made. Constantines maybe?

[Brian Weick]

For the sweep ends' (curves)
A band saw, cut shape jigs from large solids, same patter in sections ,mount back plate to join shape jigs in succession -both sides, steam the veneer,layer,glue,layer ,glue..etc..etc... Heavy 12" C clamps every 6" the entire length clamped with max torque ....dry for 24hrs, trim with either a Saw bench or band saw depending on the over all final shape and jointery....

Use lower grade for the filler veneers, no need to use the exposed veneer for the fill, its a waist of good veneer IMO.


The jointery is what is critical to the vertical back board and a little tricky but the outcome will be exceptional

B,

[Alan Schaffter]

Depending on the amount of curve to the head and footboards, unless I had a good vacuum bag setup, I wouldn't try bent laminations.

Instead I would opt for a coopered construction- bevel rip narrow boards and edge glue them to match the curves closely as possible. Smooth the outside and inside curves with planes and scrapers, or with a router sled that rides captured on two "L" shaped rails. The rails are positioned along left and right numbered templates attached to the edge of the headboard and footboard. After a pass with the router, move the template to the next number or somewhere in between. The rails should always be perpendicular to the edge of the work. Remove ridges and clean up with planes or a ROS.

[Richard Goodwin]

Thanks to everyone for their suggestions thus far. I have made enquiries and bending ply is available in New Zealand. NZ$49 for a 2400x1200mm 4.0 thick sheet, which isn't too painful. I can also get it veneered one side with European Beech, which is what I am making the bed frame out of.