steam bending

[Splinter]

After a couple unsuccessful half-assed attempts at bending some Maple base trim to the proper radius, I made a jig in the shop this morning to clamp the stock on to...

I was having trouble with the stock twisting on me as it was bent. This jig keeps it nice and straight, and the test piece came out perfect. (except for some springback because I released the clamps too early.)

Only two more to go....

The drips down the side are from the liberal amount of glue I used to assemble this thing... Its all 2x4 and MDF construction...

[ChrWright]

Did you have problems with it swelling? I'd imagine maple takes a ton of moisture to make it soft enough to bend.

[Splinter]

I did a bit of reading about it before attempting... A high moisture content will help bend easier, and with some woods it's a requirement, but the steams purpose isnt really to wet the wood. It's to help deliver the heat to the cells of the wood, warming them sufficiently to make them flexible.

It was in the steambox for about an hour, and I had everything set up so I could get it bent and clamped within 15 seconds of removal. It really firms up fast!

[Leo G]

You definitely have to account for spring back when you are steam bending, even gluing with laminated stock.

I've watched some pretty industrial steam bending. Very impressive. Hydraulic benders, large chains, steel forms, industrial steam producers. And they still stay in the forms for 2 weeks before they take them out.

[ArmchairDIY]

I don't have much experience with steam bending. However I was under the impression that you always have to allow for spring back, regardless of the amount of time it remains on the form.

[Splinter]

I did account for some springback when I built the jig.... I had excessive springback with the test piece because I removed it after an hour. It wasnt twisted though, which I was very happy about.. My previous attempts last week resulted in a properly curved yet twisted piece of trim.

[Winchester]

what kind of clamps are those? are they bessey?

i'm increasing my clamp stock soon and don't really care for Irwin all that much, which is what I have the most of... :(

Do you have a photo of your steam box? I saw a video a while ago on steam bending. interesting stuff

[Leo G]

Keep it in your pants Winchester. :mad2:

[Splinter]

Keep it in your pants Winchester.

:grin::grin::grin:

Yeah, they are besseys... the old k-body style. I also have a few peachtree knockoffs of the new Bessey Revo style. They suck... They slip on the bar when you start to get a little pressure on them.

My steambox is made up from whatever scrap I had lying around... it's disposable. I think i made it from OSB left from a crate some doors were packed in. I just drilled a few holes and shoved some 1/2" dowel rod through in a few places to hold the material up in the air for better steam coverage. I bought a Wagner power steamer (for wallpaper) from Homers to supply the steam.. works great.

[kornerking]

FYI-- Are you using non-kiln dried wood. It will work better with green wood. The fibers in kiln dried have already been changed once.

[Splinter]

Yes, it's kiln dried... It's a base molding already milled at a local supplier...

[Splinter]

Ratchet straps are dangerous when holding the curve tight on steam bent maple.

(that's a sliced up thumb... I folded the skin flaps back on)

[orson]

Ratchet straps are dangerous when holding the curve tight on steam bent maple.

(that's a sliced up thumb... I folded the skin flaps back on)

I don't think you should be posting pictures like that in this part of the forum.....oh, wait....you said thumb.... :laugh3:

[afkama]

After a couple unsuccessful half-assed attempts at bending some Maple base trim to the proper radius,

I did a project once where the design was 'Art Nouveau'. All the interior trim was bent stain grade.

We set up an Ammonia tank. Worked great. You could bend that stuff like spaghetti.

Mostly only works with hardwoods, we were using Mahogany, but I think it would work with Maple.

Of course this suggestion might be too late for what you're working on.

[Bodger]

Years ago I bought Mike Dunbar's book about building Windsor chairs. I made a few, and steam bent the back spindles and other parts. Dunbar's method allowed for making a form, and then wedging as opposed to clamping the piece in place.

When size allowed, Mike recommended putting the whole thing in the oven on the lowest setting until the wood was dry. And everything with a Windsor is green wood, except the seat usually. I had lousy luck steaming and bending kiln dried.

[naptownCr]

FYI-- Are you using non-kiln dried wood. It will work better with green wood. The fibers in kiln dried have already been changed once.

Are you saying that air dried will work better?

[Bodger]

Are you saying that air dried will work better?

Wood that has been riven from the log, not sliced, is best for bending because no cutting process has sliced across the grain, as in flat grain on a board.
This helps reduce the possibility that the wood will split out during the bedning process. All the fibers are intact and running lengthwise.

Old time chairmakers preferred their wood fairly green. Some of the joints (egg shaped tenons) were designed to lock together as the wood dried after the chair was assembled.