Limb Twist on Handle Section

[Wilderman]

Hello All,

First time posting here. I'm working on my first bow - it's an osage flatbow and I've been working through Clay Hayes's book on how to do it. I'm currently in the tillering stage but am concerned about the twist of the limbs in relation to the handle. Both limbs are more or less on the same plane as each other while the handle is lightly twisted. The handle is currently exactly 2" all the way around. I can see the handle twisting when I put the bow on the tillering rack.

1) How big of a deal is this?
2) If I wanted to fix this, should I use heat to twist the limbs? Or can I work on trimming the back of the handle itself? I think just having the handle depth (belly to back) slightly uneven on each side (maybe 1.5-1.75" on one side and 2" on the other side) would change where the force of the bowstring is pulling in relation to the plane of the handle.



Thanks!

[Aksel]

Roughly how many degrees is one limb twisted in relation to the other? Most bows I make have some degree of twist.

I think twist (especially if it´s only in the handle) is cosmetic unless severe + 45 degrees although it makes even bend during tillering slightly more difficult to judge. You have to look at the bend from all sides many times over to judge the bend. Also you might have to consider what kind of nock you are making since limb twist can make the string sit uneven on the nock. It might slip.

If lots of twist I go either for pin nock or a tie-on nock.

If twist is in the outer limb I might try and steam/heat correct it.




EDIT: now I see the photos, I wonder: where is the twist - it looks straight to me   

[Hamish]

I can't see much in the way of troublesome twist from the photo's, What I do see is the deflex in the right side limb due to the handle.
"If I wanted to fix this, should I use heat to twist the limbs?" Dry heat, on a reflexed form would be ideal to correct the limbs, and make them more evenly balanced. I would not try and use heat to bend the actual handle itself. Its too thick, and you would strongly risk splitting the transition of the fade/dips.
I wouldn't do much bending at the kink, but rather get the intended effect along the whole length of the limb.

"Or can I work on trimming the back of the handle itself?" I would never advise that. It could work but you risk cracking even with a supposedly non bending handle.

[bentstick54]

Looks like both limbs are twisting right off of the handle to me. I made a simple caul out of a 2x12-12’ cut in half. Used 1/2 of it to cut the reflexed board out of, glued and screwed it to the 6’ piece of 2x12. Then used the other cut off piece on the back side for a straight form.
 I clamp the bow handle down and use shims to clamp it to the back of the caul. Then I start heating at the end of the fade 4” or 5” at at time and clamping it down when it gets plyable. I can take any twist and side bend out out the same time, then move down to next next section and repeat, and lightly hitting what I already have clamped just to keep it warm until the entire limb is done. Then I like to leave it clamp 4 or 5 hours to make sure it is entirely cooled and set before unclamping. I try to heat mine slow enough not to scorch the surface.
Make sure you wood is dry or you can develop drying checks it the back of the limbs as you are forcing moisture out. I solved 95% of that by shellacking the back, and lightly rubbing vegetable oil on the belly.

[Pat B]

First, welcome to PA, wilderman.
 What I think I'd do is continue tillering the limbs and see if the limbs twist more as the limbs are stressed of are they staying on the same plane?
 A caul, clamps and wedges, with dry heat(heat gun, etc), like others have suggested is the way to remove the twist. Leave the handle area blocky for now. You don't need a finished handle to tiller the limbs and it gives you a place to clamp the bow to the caul or in a vice for heat corrections. Leave last 6" of the tips wide also. You can adjust the string tracking later once you get to first low brace.
 If the limbs are on the same plane and the twist is in the handle you can shape the handle so it is in the same plane as the limbs later on.
 Keep asking questions and posting pics and we'll have you shooting your new bow soon.

[superdav95]

Great advise here.  Only thing I’ll add is if you wanted to add any reflexed tips of flipped tips you may want to incorporate that into your caul jig design when and if you build one.  You want to avoid double heat session an area more then once for corrections when possible.  You might get away with it sometimes but eventually it gets real brittle.  Heat corrections work well for Osage.  If you go this route of flipped tips in this build start at the tips of one limb working back toward the handle and let it cool.  Then do the same on other limb to match.  This can be used to align your tips with handle and fix you twist at the same time.   Best of luck.  Just how I do it when I plan on flipping tips and fixing twist or other alignment issues. 

[Selfbowman]

You can cut a slot in the handle and heat a thinner section and get the twisted section out .then fill with a shim and glue new section on the handle belly.

[Selfbowman]

Finished

[Selfbowman]

Pic

[Eric Krewson]

I would start by cutting the belly of your handle at an angle that is on a plane to straighten out most of the twist. If you have 2" of width in your handle you should have enough room to get the handle sides parallel with your limbs.

When I get billets ready to splice, I put the belly of a spliced section on a flat surface and sight down the limb. I flatten the splice end belly at what ever angle it takes to remove as much of the twist as I can before I cut the splice.

[superdav95]

That worked out great Arvin!  I’ll have to remember that one. 


Eric.  I’ve seen you fix too and it’s on my list of fixes to try in the future.