How to bend wood like this - Outdoor furniture project

[jack duren]

You’ll probably have go to 3/16. Depending on width you may need 1/8..

Air or kiln dried makes a difference

[Alan Lightstone]

When you make the layers for the forms, make one that's "da bomb" and use that to template route the remaining layers for a perfect form.

I agree. That's the game plan. I'll bandsaw outside the line by 1/8" or so, then pattern rout the remainder.

[Kevin Jenness]

Wood arrived yesterday. Busy making the forms now. Using 3/4"MDF. OMG the weight of 8 of these on top of each other to accommodate the 5-1/2" wide wood that needs to be bent will require help, to say the lease.

I made the curved portion of the form out of 1/2" MDF using a Carter Accuright circle cutting jig that I had on my bandsaw. What a PIA. Shoulda just made a trammel with my router. Probably would have come out a little smoother too, though mine will work. Killing me the waste of MDF when I'm done. Not that I ever use MDF, but still taking a ton to make the bending form.

I couldn't lift or transport 4x8 MDF sheets, so I'm going to make this out of 2x4 MDF sheets and domino them together.

Now I need to build a larger steaming box than I have, and probably get a larger steam generator. Lots and lots of work to do. Any good suggestions for steam generators. Somewhere I read that wallpaper steamers, whatever they are, are good.

You can steam wood in a bag instead of a box and fold it up after use. https://www.youtube.com/watch?v=50uXPPt8-VI I have used a couple of Earlex steam generators and a 30 gallon bag successfully, you might get by with one and a blanket for heat retention. For larger quantities of steam the propane burner and gas can shown in the video are pretty common.

Have you done a test bend with dry strips to ascertain the thickness needed for lamination w/o steaming? The whole process you are planning is very laborious compared to straight lamination or segmenting the curve. I have never done that, and no doubt it will work but I wonder how flat across the laminations will be after steaming/drying and how tight your finished gluelines will be. Seems like some testing would be a good idea before slicing up all that material.

A small furniture shop near here has done a fair amount of steambending for thick chair parts using a ratchet winch and bending straps with endstops, milling the parts to final size/shape after bending. That would be my preference on aesthetic grounds.

[Alan Lightstone]

Well, the verdict is in on using a single Earlex steamer. The highest temperature it could get to was 174 degrees F after one hour. So I installed a second Earlex which I had, and that gets up to 212 degrees F in about 30 minutes.

Several areas of the box are leaking some water. Can caulk stand up to that heat, or is there something else I can use to seal it from the outside without taking things apart?

I may definitely wind up just using dry bent lamination, but was hoping that by steaming the laminations first and pre-bending them, then later putting them back on the form for a more normal bent lamination I could use thicker laminations. Clearly much, much more work this way. May not be worth it, but well, well down the path.

No question in retrospect that segmenting the curve would have been far easier, though I really don't know if I could produce identical pieces/curves that way. No CNC machine here.

[Steve Demuth]

Steamboxes always leak water. If you want to control the leaks, I would assemble the box with a temperature rated caulk or roofing compound in the joints (and, I predict, it'll still leak some), set the box at a slight angle so the water all runs to one end, and make the water come out through a leak (hole) of your choosing on the downhill end.

Your plan to steam bend, then glue up in a second step is absolutely sound. I've done it many times.and there is no reason for you not to succeed. You should have no difficulty getting 1/4" laminations to work this way, although my personal preference is to use slightly thinner lams than that - usually 5/16" or 1/8" - just because they soften up so much faster in the steam bath. On the other hand, they also cool very quickly, so you need to be quick and efficient in getting them from steamer to form. 1/4" will give you noticeably more leeway in that regard.

[Bradley Gray]

My boxes have a drain hole.

[Kevin Jenness]

No question in retrospect that segmenting the curve would have been far easier, though I really don't know if I could produce identical pieces/curves that way. No CNC machine here.

I don't see why not. Join the segments, bandsaw the curves and clean up with a segmented flush trim shaper cutter and/or spindle sander. A compass plane could be used with care at the joints' change in grain direction.

[Alan Lightstone]

You’ll probably have go to 3/16. Depending on width you may need 1/8..

Air or kiln dried makes a difference

Ouch. Lots and lots and lots of laminations.

[jack duren]

Is what it is..1/8x 6=3/4 bend all at once..