Steam straightening full staves

[bigcountry]

I see these staves for sale, straight as an arrow, usually osage.  They list them as steam straightened.

I have steamed handles, tips and heat gunned osage.  But only when they are reduced down.  Never a full sized stave. 

So who here can steam out bends out of a full sized stave?  Everytime I have tried to take out a bend out of a handle I sometimes get slight cracks and that takes a significant amount of force using a vise and blocks of wood.

I have always worried trying to do it with a full sized stave.

[wizardgoat]

Guys make a tube out of 5 or 6" ducting. With a Tee fitting in the middle that go's over your boiling water. I've never done it, haven't needed too, but it looks very effective.
Pretty sure, the osage staves your seeing online that say steam straightened are done when they are green. I believe shellac is used to prevent excessive checking

[Pappy]

That is what I use wizardgoat. Don't do it a lot but sometimes on green staves where steam works better. I cold bend everything on the form and have all clamps and shims ready .When to take it out you don't have a lot of time so having things ready is a must. Also have the stave as close to floor tiller as possible helps also.
   Pappy

[Eric Krewson]

Early on in my bow making I would steam full length staves. It was my finding that they would often go back to their former shape after you had them off the caul for a few days.

[bigcountry]

Hmm, maybe that's the trick to do it green.  but I agree, must be reduced down to min dimensions. 

I usually steam bend dry osage.  I recently only use a heat gun.

[Dances with squirrels]

I have done loads of full length staves like that. Green osage, 4" stove pipe... the T in the middle fits right down into a camp coffee pot.

Prior to going into the steamer, my staves are 1 3/4 - 2" wide, tapered from about 3/4 to 5/8 thick, with extra wood for the handle and dips, two coats of shellac on the back. I throw a heavy blanket over the pipe for insulation. Steam for about 1.25 - 1.5 hours... and work quick cuz it cools fast. The faster the corrections are made, the hotter theyll be and the more likely they'll stay. It's really nice to have an experienced helper and a plan... but not necessary. While I have taken them off the caul a few hours later with good results, if I'm not in a rush, I like to leave them on there for days, maybe a week, or longer... until I 'need them', because cooling AND drying there seems to reduce the risk or them returning to their previous shape somewhat. I keep more than one caul around for that reason too.

[PEARL DRUMS]

I made a rig and started my first few that way. Ive since junked the rig and use dry heat and a caul on dry wood.

[Pappy]

Yew seems to do better for me with dry heat, but Osage does fine with steam, I only do it if it is less than 2 years old, any older I use dry heat also.
    Pappy