Steam bending

[Marc St Louis]

From what I can see you are leaving your tips rectangular.  Try rounding the belly into a shallow D section and sanding the edges.  I found this helps a lot, along with a metal strap, with HHB.  Also follow one growth ring from the tip to well past where the bend will end

[PatM]

. So far nobody has mentioned anything I haven't tried.

 Hey! I mentioned boiling! lol

[upstatenybowyer]

Wow, thanks for the tip Marc, especially for bending HHB. I've had the hardest time bending that stuff.

I just got done bending yellow birch for the first time and it was very cooperative. Just thought I'd throw that out there. 

[DC]

. So far nobody has mentioned anything I haven't tried.

 Hey! I mentioned boiling! lol

Sorry Pat

[DC]

I tried Marc's suggestion. Got it all set up and bent the dern thing backwards Try again tomorrow. Meanwhile, I remeasured(more accurately) the radius on my bending jig. It's 2 1/2" not 3 1/2" like I said at the begining. Is that too tight?

[Ballasted_Bowyer]

Have you tried different temperatures? Each wood has some temperature that is too high or low. Expirement and see if steam is the right temperature. If the wood gets too hot it will fail in tension because the chemical bonds are decayed. Also there is a radius to thickness ratio that is at the limit of what you can do. This varies according to species. You might make a note of the radius at which the wood pops and design accordingly.

[bjrogg]

DC I'm gonna see if I can look back in my pictures and post a couple that might help. HHB acts the same way and I had a lot of trouble at first bending it. Like Marc said round of the edge on belly side to a D profile. Speed getting it ready is so important don't waste a split second. I like how I have the end of my caul now I don't need a clamp and that speeds things up so much. I also like my lid for my kettle. It's just a old aluminum kettle. I cut two slits in the top and bent them straight. I can Stick limb tip in opening belly down. I usually have to steam my HHB at least a hour and even then I really turn the heat up to a good roiling boil the last 15min. I always have my clean leather gloves, clamps, pads and if possible another set of hands right ready. I don't force it I have done it enough now I can tell when it's going to bend and when I have to put it back in the steam. I also use the metal strap. Good Luck
Bjrogg

[bjrogg]

The picture on the caul is before I used metal strip but I just slide it in place with the limb. The wood in the kettle isn't really a bow limb it's just a piece of wood for demonstrating maybe this might help made a world of difference for me
Bjrogg

[---GUTSHOT--->]

I purchased a earlax steam generator from Amazon. Works 10 times better than pots and pans and aluminum foil. All woods I've bent with it was like butter

[DC]

Success!!  Green wood, increased the radius from 2.5 to 4", thinned the limb to 7/16", steamed for an hour and followed Marc's "D" shape. I increased the radius when I found that part of the curve was 2.5". Now that it's all actually circular at 4" it doesn't look that much different. Next will be dry but soaked wood but I'll boil it for an hour instead of steam. I'll let this one dry for a while and then see if I think that 7/16" is thick enough to be static. It wouldn't break my heart if it works a bit.
 Now I can start going the other way, start tightening the radius to find the actual limits of this wood

[PatM]

A good source for discussion on this is forums or books regarding making curved handled canes and walking sticks. Those guys really know their stuff.

[Danzn Bar]

I purchased a earlax steam generator from Amazon. Works 10 times better than pots and pans and aluminum foil. All woods I've bent with it was like butter

+1 on that Paul ....
DBar

[DC]

I have a similar thing. Mine is a clothes steamer but it makes lots of steam.

[Danzn Bar]

That should work well DC what type of steaming chamber do you use?
DBar

[DC]

I have a little box made out of 1x4 that I'm using for this bit most of the time I use bread bags or some newspaper bags that I got from my grandaughter when she quit her route. I like the bags because you can bend stuff while it's still steaming and leave it steam for a while after it's bent.

I tried boiling one this afternoon and it failed. I'm going to quit for a while before I start breaking important stuff. I think what I've learned is that if I want 90 degree bends in OS I'm going to have to kerf them.