Author Topic: Tillering advice  (Read 1532 times)

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Offline Bowyer23

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Tillering advice
« on: April 18, 2020, 03:09:47 am »
Hey guys,

Make this bow from Osage branch that I had. Only problem was that it had a large bend which I had to heat and try and bend straight. It's resulted in this hinge type bend, even though the amount of wood in that area shows that the hinge isn't from too little wood. Tried heat bending it back a few times which works, until the string is put back on and it just forces the hinge to return. Advice would be much appreciated :)
« Last Edit: April 18, 2020, 03:17:58 am by Bowyer23 »

Offline stuckinthemud

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Re: Tillering advice
« Reply #1 on: April 18, 2020, 03:39:10 am »
It would be helpful to see a photo of it unbraced. If there is a kink in the wood at that point then the solution is different from if the wood is straight when unbraced

Offline Bowyer23

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Re: Tillering advice
« Reply #2 on: April 18, 2020, 03:46:41 am »
Thanks, here you go :)

Offline Artus

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Re: Tillering advice
« Reply #3 on: April 18, 2020, 05:00:05 am »
Keeping the natural hinge in mind, I`d still say it bends too much there at the left limb. The inner 2/3 are not bending at all or just very little. The right limb looks ok, just on the area on the left side from the reflex is too stiff.

Offline George Tsoukalas

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Re: Tillering advice
« Reply #4 on: April 18, 2020, 08:25:07 am »
It is tough to evaluate that type of character bow's tiller on line. You have to make sue that each portion of each of the limbs does its share of bending.

TBB 4 has a chapter on character bows.

Jawge
Set Happens!
If you ain't breakin' you ain't makin!

Offline dylanholderman

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Re: Tillering advice
« Reply #5 on: April 18, 2020, 09:11:39 am »
How long are you waiting between heating it and stringing it again?

Offline DC

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Re: Tillering advice
« Reply #6 on: April 18, 2020, 09:19:26 am »
You said a branch. Is it possible that there is more sapwood in the hinge? It sure looks like garden variety hinge to me. It's weak there for some reason.

Offline Eric Krewson

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Re: Tillering advice
« Reply #7 on: April 18, 2020, 10:50:21 am »
That limb should be easy to make dead level straight, because it has been stressed a bit so far I would put a little reflex in it before I started tillering again to try to even things out.

Offline Bowyer23

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Re: Tillering advice
« Reply #8 on: April 18, 2020, 11:05:23 am »
Waited 24 hours between heating and stringing so That shouldn't be the problem. Yeah it was a branch so it has all sorts of twists and tangles. No sapwood though got rid of that as soon as I got the branch. Yeah it is easy to get dead straight, it's just that as soon as it's strung it returns back to hinge position you can see! Thanks for all the replies, what about if I straighten the limb again and then heat treat the entire bow? The limbs bend the same initially when I straighten the hinged limb, it just doesn't last long. Would heat treating potentially combat this?

Offline Eric Krewson

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Re: Tillering advice
« Reply #9 on: April 18, 2020, 12:08:53 pm »
yes

Offline Pat B

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Re: Tillering advice
« Reply #10 on: April 18, 2020, 12:15:03 pm »
When was the branch cut?
Make the most of all that comes and the least of all that goes!    Pat Brennan  Brevard, NC

Offline Bowyer23

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Re: Tillering advice
« Reply #11 on: April 18, 2020, 04:07:54 pm »
Branch was cut recently, although when all sapwood and bark was removed heartwood has a moisture content of 9%

Offline Eric Krewson

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Re: Tillering advice
« Reply #12 on: April 19, 2020, 07:59:43 am »
Sometimes you have to be creative to fix a problem;

I grabbed two of what I thought were matched osage billets to make my latest bow, the rings were the same and 10 years of shop sitting had turned them into exactly the same dark color. As I cut the splices I realized the billets weren't even close to matched, one was yellow osage and one was dark red osage, I thought it wouldn't matter and proceeded. Turned out the limbs had a different recovery rate, one was snappy and one was mushy. The red limb would relax after 5 or 6 shots and throw the tiller way off.

I heat treated the limbs, which almost evened them out, then heat treated the red limb a second time, that did the trick and made the bow hold tiller, it became a good performer and very stable shot to shot.

Another thing; why does he splice go up above the arrow rest and handle? Some old man thought he had measured the limbs correctly to have the top limb an inch longer than the bottom so the snappier limb would be on the bottom. Turns out he had them reversed so he moved the handle down to get things back the way they were intended.

 

« Last Edit: April 19, 2020, 08:08:50 am by Eric Krewson »

Offline PatM

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Re: Tillering advice
« Reply #13 on: April 19, 2020, 08:08:08 am »
I think your hinge is broken down to the point where no amount of heating it will make it hold.

 If you heat treat the rest of the bow it will become relatively stiffer while the hinge will remain as it is.  That will make it even worse.

Offline Eric Krewson

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Re: Tillering advice
« Reply #14 on: April 19, 2020, 08:14:32 am »
I tend to sorta' agree with Pat, you never should have strung that bow with the wonky limbs.

With a good heat treat you melt the ligons in the wood and make it new again but there are limits, especially in badly hinged areas.