Ssssssteam Heat Pt 2

5901 Views 76 Replies 12 Participants Last post by sunnybob, Jun 4, 2018

DaninVan

Discussion Starter · Apr 7, 2018 (Edited)

I have an actual woodworking query (minds boggle, I know).
OK I'm making up a couple of WR cedar panels...1/4" x 11" W x 48" L.
Each panel is made from 3-4" x 48" strips...TitebondIII. No problem so far; all going well. Now I need to bend each panel across the width. Ie; I'll end up with something that looks like a wing, when the two bent panels are assembled together.
I've cut a bunch of 3/4" thick forms...11" long x 2" tall. The profile was a natural arc formed by bending a thin strip to touch the three critical points (two ends and the ht.)
Now Considering it's fairly thin Cedar, how long should I have to steam it for before attempting to bend it to the form? Any helpful suggestions? (I emphasize 'helpful'... :x )

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JOAT

· #2 · Apr 8, 2018

Well, have never steamed wood, but subscribe to WoodenBoat, which has articles on steaming wood - wooden boat builders seem to steam more wood than any other woodworkers. Have read on it from other sources as well.

I think it is a combination of the volume of the wood, type of wood, heat of the steam, etc. I don't think I have ever seen a formula for it. I would say steam some, see how it bends, and repeat as needed, until you get a satisfactory response. That's how I would do it anyway. Five cents for the information.

Reactions: 2

woodknots

· #3 · Apr 8, 2018

Dan - years ago, Norm Abram did a show on steam bending. Not sure if you've seen it.

Reactions: 2

DaninVan

Discussion Starter · #4 · Apr 8, 2018

I'm worried about the glue joints failing. My understanding is the glue needs to cure for at least three days before stressing the joints, especially with moisture.
A lot of these DIY steam boxes are all wrong for doing a wide panel. Now I need to build a steam chamber that will work, and allow me fast access to the panel when it's ready.
The cheapest part of my 2x4 challenge project is the 2x4...

DesertRatTom

· #5 · Apr 8, 2018

Trying to recall a baseline time from a Norm Abrams special a couple decades ago. Steam bending is mainly about the form and clamping the piece to it. Maybe this will help.

Stick486

· #6 · Apr 8, 2018

DaninVan said:
I'm worried about the glue joints failing. My understanding is the glue needs to cure for at least three days before stressing the joints, especially with moisture.
A lot of these DIY steam boxes are all wrong for doing a wide panel. Now I need to build a steam chamber that will work, and allow me fast access to the panel when it's ready.
The cheapest part of my 2x4 challenge project is the 2x4...

no matter... the heat from the steaming will plasticize the glue the joints will separate...
run a test..
take your glue brush w/ dried glue on it and hold under hot water or dip it in boiled water... the glue will wash right out of the brush...
you should have steamed the wood 1st for 10~15 minuets, then shaped and glued it up.....

Reactions: 4

Cherryville Chuck

· #7 · Apr 8, 2018

Epoxy might hold in the steam but I'd test that first. All other glues are some form of plastic like Stick says. All the stuff I've read about steaming say 1 hr per inch thickness. But it will have to be pretty limp to bend it across the width.

Stick486

· #8 · Apr 8, 2018

DaninVan said:
I'm worried about the glue joints failing. My understanding is the glue needs to cure for at least three days before stressing the joints, especially with moisture.
A lot of these DIY steam boxes are all wrong for doing a wide panel. Now I need to build a steam chamber that will work, and allow me fast access to the panel when it's ready.
The cheapest part of my 2x4 challenge project is the 2x4...

here...

...

Reactions: 3

Herb Stoops

· #9 · Apr 8, 2018

Dan IMHO I think you should build a form and bend before you glue them up. I did some for the inside of a trunk lid out of 1/4" redwood one time. I wrapped them in towels and kept pouring boiling water on them then after an hour took them one piece at a time and bent them to fit. But I was bending them lengthwise. You want to bend them width wise? I hope the bend is not too extreme.
Anothother thing to think about n do your steaming in an open area outside your shop or you might get condensation on all of your tools.

Herb

Reactions: 5

DaninVan

Discussion Starter · #10 · Apr 8, 2018

In my own defense, I didn't know what I didn't know.
Herb; no way was I going to do the steaming indoors, for starters I thought I might use the Coleman gas stove to 'boil' the water...outdoors!*
Re the bend; as I mentioned, it's a 2" rise in 11" of span. basically 1:6- When I take the panels out of the clamps I'll run it through the planer again to clean it up. That'll mean that it's even thinner than the current .25".

(*My neighbor was burning some brush in a burning barrel this afternoon. He didn't notice that he'd accidentally thrown an aerosol can in with the branches.
Startled the daylights out of me, when it went off. He said the barrel jumped a couple of inches vertically.)

sunnybob

· #11 · Apr 8, 2018 (Edited)

Thats not too big a curve. Did you know you can bend wood by dry heating as well?

I would try putting the separate panels under mild clamp pressure on the former and use an electric heat gun at the centre, working outwards and slowly increasing clamp pressure you go.
Once the panels have some memory of the shape, glue them up and immediately clamp them so the glue holds the shape.

If you do want to steam, you dont have to build a box for just one time use. A plastic sleeve around the wood will do the trick.
Heres a third option

Reactions: 1

Multiwood

· #12 · Apr 8, 2018

Dan I have made several items with bent lamination and I do not steam them. I'm working on a table with bent lamination on
the edges now. You should use a Polyurethane glue for bent lamination. I use Titebond it has a purple label.

Multiwood

· #13 · Apr 8, 2018

Dan here is a picture of a table I made with Ash & Cherry bent laminated legs. The legs were bent into a form
and I did not use steam.

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Stick486

· #14 · Apr 8, 2018

Dan...
have you considered doing a layup instead???
how about veneering bendy plywood...
make your own bendy plywood from Spanish ceder veneer...

Reactions: 1

Stick486

· #15 · Apr 8, 2018

you got a rendering of some kind of your idea/plan/project...
is it to be open ended...

DaninVan

Discussion Starter · #16 · Apr 8, 2018

Stick486 said:
Dan...
have you considered doing a layup instead???
how about veneering bendy plywood...
make your own bendy plywood from Spanish ceder veneer...

1-8' 2X4. That's the 2 x 4 Challenge, Stick.
(And accessory hardware etc.)

I'm going to go through all the material you guys have posted...I never really wanted to use steam if there was another way.
Thanks for all the input, Guys; lots to consider.

Stick486

· #17 · Apr 8, 2018

DaninVan said:
1-8' 2X4. That's the 2 x 4 Challenge, Stick.
(And accessory hardware etc.)

I'm going to go through all the material you guys have posted...I never really wanted to use steam if there was another way.
Thanks for all the input, Guys; lots to consider.

brute force applied over time...
segment it w/ thicker material and shape the top...

Reactions: 1

Cherryville Chuck

· #18 · Apr 8, 2018

2" offset in 11" with a 4" width to bend. That sounds hard to do. Why not saw it to shape?

Reactions: 1

DaninVan

Discussion Starter · #19 · Apr 8, 2018

OK; we're losing sight of the objective. I should have been more explicit about the parameters I need to work within.
As I mentioned in my last comment this is about getting the maximum amount of material out of ONE 8'-2x4 ...species doesn't matter, although my club has rejected hardwood this year.
Every sawcut, planer cut, offcut reduces the material actually available (somebody's eventually going to think of making paper from the sawdust)...
My project isn't one I've seen done before; it's a large-ish musical instrument. My own design. No idea whether it'll work as intended(?).
(Did I mention that my musical talent is pretty much limited to baked beans?)
The thin panels are a sound box; something along the concept of a guitar/mandolin/violin, but very different.
I figure the sawing into thin strips probably used up 15-20% of the original material...I'm sort of stretching the rules a bit because I started with a rough sawn 2x4... that's an added 1/2' in both width and thickness...it was clear quarter sawn, done on a bandsaw mill and really clean on the faces, just a bit of light fuzz.
No drawn plan, Stick; it's all in my head, under constant revision. So many conundrums; wait! That's what I should have made; a conunDRUM

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Stick486

· #20 · Apr 8, 2018

DaninVan said:
OK; we're losing - it's all in my head, under constant revision. So many conundrums; wait! That's what I should have made; a conunDRUM

you realize you are holding the door open and have thrown out the have at it mat...

so change the design,,, again...
some wooden passive sound box images...

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