Help on Elm Bow with Prop twist

[Mantis Flint]

Hey All,
New to the forum here, looking forward to it.

I am working a Siberian Elm bow right now. The stave is green, and has significant propeller twist in one limb. It is almost floor tillered, any thoughts on straightening the limb? Should I wait for it to dry, steam it, boil it, clamp it has it dries, use dry heat? Any good jigs? Any help would be hugely appreciated.
Thanks,
Mantis

[BowEd]

I'll give this one a try here.I've clamped a number of green elms to forms when wet to induce reflex.That's what I would do right now but if it's at floor tiller already there might not be much drying left for it to help take the twist out.Chances are it will a little bit,but you'll have to let it dry for another 3 weeks inside the house.That way it would be easier to take the twist all the way out with dry heat later on a form.Elm takes heat treatment well.

[Del the cat]

Here's how I've done it:-
http://bowyersdiary.blogspot.co.uk/2014/06/removing-twist-from-yew-primitive.html
Del

[BowEd]

Cool Del..I'll agree it takes about as long setting things up on a form as heating it during the process and should of explained a process of taking the twist out.I usually do it with dry heat which I think is more permanent and since the limb like yours is usually past floor tiller and thinner.On a form with the profile similar to your bow in width and arch I secure the limb with a c clamp below and right at where the twist originates from in the limb toward the handle end dead flat with a buffer 1.5" piece of softer wood on the belly.Then put a small accomadating thickness piece of leather under the side of the twist that's touching the form on it's back first between the form and back of bow.Half or less the width of the limb.Then above the twist toward the tip side I will put a c clamp on the high side half  the way I want to take the twist out or opposite the side of where the leather sits on that half of the limb,and heat the area the twist originates from going a little past dead flat as you heat to account for spring back after cooling.The closer you can get to the area with a clamp above the twist the less wood you need to twist.Twist in a handle can taken out too.
This can be done as you heat treat a limb from handle to tip too and grab the tip side of the limb and twist it and hold it there to take the twist out too.There are many ways.You got to think out of the box a little and get er done.

[Springbuck]

  Del got it, but let me add, or re-iterate some things.

  I'm hoping you left some width toward the tips, because that helps with the clamping. Howsome-ever, clamp it on a form, slowly, with hard clamps (like c-clamps , not rubberbands or spring clamps), removing twist as you go from handle toward the tips.  Use lots of clamps.  I have found that even if you have a consistent even twist, if you try to clamp it at the handle, then right out at the end of the limb, the torque will find any weak spots, just like overdrawing a bow during tillering will find a hinge. This either over-corrects the twist in that one spot without removing much twist anywhere else (so the limb now dips side to side, twisting a little one way, then the other), or can just crack or break at the edges or split in the middle.

  You can heat green wood to help yourself, BTW, just don't do sit so aggressively that you cause checks or new warps.  Keep it around boiling temps max, or use steam.  Pad your clamps, because wood thin enough to clamp to shape si close enough to finished thickness that you don't want big divots, and green wood will take big divots.

  Then, lastly, once it is good and dry, I would definitely toast the belly (I'd do this on elm anyway) to really set the corrections.  BUT, CLAMP THE WOOD DOWN on your form or caul when you do this.

Good luck.

[riverrat]

hope you have better luck than me. i tried heat bending, steaming and putting in a form for almost a month, heat bending and putting in a vice for 3 days. nothing took it out. once left over night, the next day right back to square one.sometimes, most times heat bending works but theres that occasional piece of elm that would rather propel a airplane than send a arrow lol Tony

[Pat B]

Look on the "Archive" page. I did a build along from beginning to end on a 60" elm static recurve. It had some twist in it that I removed using a heat gun and a little olive oil.

[George Tsoukalas]

Heating green wood with dry heat may be problematic.
Jawge

[BowEd]

George is right about checking happening dry heating green wood,but if it's dry and you heat it slowly and enough it will take the twist out without cracking.The only way it cracks if it was'nt hot enough.I've done it a lot of times.
Pat's picture turorial may help you.