steam bending wood

[Carpentersreef]

I'm making some doors for EmilyB's 155g bowfront light canopy, and was wondering if anybody else has tried this and if it has stood up over time. I'm using 1 x 2 red oak strips for the 2 front doors' frame. I've got them all steamed and bent, I'm just wondering if they could have a tendency to straighten out over time?

Thanks,
Mitch

 

[Anonymous]

I think that once they dry COMPLETELY from the steaming, they are perminently bent. Like the bottom of rocking chairs.

I can call a few woodworkers I know and Ask them.

B

 

[Carpentersreef]

Thanks, B. I'm actually wondering if anyone has experience with bent wood inside a possibly humid atmosphere that would exist inside an aquarium canopy.

Mitch

 

[Rich-n-poor]

Darn you mitch....

I never even considered the humidity issue. but I would imagine that if they are primed and sealed and/or polyurethaned (which is what I plan to do) the humidity cant get in

_________________
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[Carpentersreef]

Yeah, I had to re-bend the oak to compensate more for spring-back than I planned, and when I took the bent pieces out of the steamer for the second time, they were pretty much straightened out again. The temp required for steaming is about 200 degrees, and I doubt that even a canopy that has no cooling fans would get that hot, but I thought I would ask, anyways.

Mitch

 

[Anonymous]

Mitch,
Are there going to be any MH in the canopy? They might heat up the warm air -just- enough to cause trouble. I would almost go so far as to put in studs and screw into them from the front of the canopy, and put another piece of 1/4"-ish over that piece.

It would envolve some nifty miters!

But then again, I over engineer everything...

Rich, I would stay away from Polyurethane. It has a tendecy to 'yellow' over time. I would go with a spar urethane. It is about $30 a gallon, and is much better. IMO

B

 

[Carpentersreef]

The oak pieces will be for the doors, (2 on the front), so there's nothing to attach them to. The doors have to open, so the oak will have to retain the shape on it's own.

Mitch

Did you see the thread that EmilyB posted that had a pic of the canopy?
it's here

 

[JPG]

Saw an episode of "The New Yankee Workshop" a few months ago where Norm Abram was building a door for a corner cabinet.

He glued up several 3" or so boards with a slight miter which gave it a sort of faceted look and then knocked down the protruding edge at the miter with a sander or plane to give it an almost curved appearance.

I remembered this as I have a corner tank and thought the idea would work for making the curve on the front of a canopy.

John

 

[Carpentersreef]

That sounds like a good idea. The trick would be to end up with a smooth enough curve so that the finished curve looked consistent. I've seen Norm make some really big jigs for his bandsaw, and run pieces through that, too.

Mitch

 

[billzie]

Hmmm, NORM! My girlfriend is jealous of the time Norm and I spend together. Seriously, what about used a few stacked 3/4" plys that are cut to the shape of the curve and mount your fascia to it. I've thought about this for a corner tank. I'm thinking about doing that for the frames of the doors and using 1/4" pine ply and 1/4" oak ply laminated together for the fascia, bending the pine ply on the stacked ply frame curves, appying the adhesive then bending the oak ply over, clamping the hell out of it and tacking with brads (hey, I can talk like Norm). Let me know, what you think. Bill.

 

[Anonymous]

I finished a hood for a 46 gal bow several months ago and do some bending for wooden boats also. I used a laminate cold forming technique for the hood. You could also use some sort of kerf bending method.

If you go with traditional steam bending I think you had better plan on some straightening of the bent pieces over time unless you use some sort of permanantly attached frame. If I were steam bending the peices I'd definitly plan on some sort of hidden frame to make certain that the pieces stay stable over time.

HTH,
-Sci

 

[billzie]

Sci, thanks for the reminder. I almost forgot about the kerf cut reliefs to allow an easier bend. Bill.

 

[Tidybowlman]

Im a Carpenter,

Steam bent wood will retain its shape, you just need to follow a few rules, once it is bent to shape, it must be dried out, if you started with nice kiln dried at about 14 % or less moister you need to dry the piece out again, this dosent take as long as green wood as the wood is now a skeleton, not a living thing anymore the cells will not accept water back in, thats why wood floats for a long long time before sinking. also there are excelent glues on the market today, epoxies, and one i would use for this, resourcanol, spelling could be wrong, its a powder and a liquid mix, ive glued two pieces of oak together with this without clamping, and the next day not be able to break the joint beating it with a hammer. next you want to completly seal all surfaces, as not to allow any humidity or moisture to react with it both sides, heres why, if you have ever looked at a house that has shingles that are cupping, this is because the back sides of the shingles were not sealed, only the fronts the front side gets the Sun, and is sealed, so it just stays the original shape, but the back side soaks up moister and expands while the front stays dry. Also, most rocking chairs rockers are cut out of a wide board, or glueups, being on the floor and scraping on the floor would open the wood and be more apt to take in moister and unbend, also remember that wooden boats are built "old shool" with steamed bent wood, they steam it and bend, and either peg it down, or use screws, or glue, a sealed seaworthy boat just dosent unbend when you put it in the water. Hope this info helps in your decisions. good luck!

Tidy

 

[Carpentersreef]

Thanks, everyone for the replies!
I think I'm going to go with 2 or three layers of 3/4 X 3/4" cut plywood pieces. The springback from steambending was still too much, even though I compensated by reducing the radius by 1/2" over the length of the 35" frame pieces.
Mitering together individual pieces would result in a frame that stuck too far into the tank for what I would like.

Sciguy,
Do you know if the springback from laminating plys together is as severe as that from steambending?

Tidybowlman(

)
I've never heard that theory before about asphalt shingles. My understanding of shingles bubbling up is that they become overheated. Shingles are made up of 3 layers, the bottom being tar-impregnated felt, with a layer of tar only next and granules on top to protect the tar underneath from uv rays from the sun. The reason for the bubbling is because the shingle becomes overheated, melting the tar and oversaturating the bottom felt layer, resulting in the swelling. This is a problem with roofs that are insufficiently ventilated with adequate soffits and upper vents. Ventilation is extremely important for keeping roofs cool, both in the summer and the winter, with the winter problem being ice dams.

Mitch

 

[Anonymous]

I had very little springback. I'd guess 1/4" of springback over a 36" run. I only laminated 2 layers of plywood. Since you are using three layers of plywood I'd guess you'll experience even less.

You might want to try a small test piece to see how the plywood performs. I'd cut three 1" wide pieces of the plywood and do a glue up. Then you'll know exactly what will happen. If there is too much springback you might want to consider using kerf cuts in conjunction to lamination.

Hope this helps.
-Sci

 

[Carpentersreef]

Thanks, Sci

Happy New Year!

Mitch