Author Topic: Tiller Changed, Help me understand why?  (Read 9831 times)

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Offline artcher1

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Re: Tiller Changed, Help me understand why?
« Reply #15 on: May 06, 2009, 02:32:52 pm »
Whats your doing here is monitoring for any changes in tiller George. Board of stave, change happens ;D!

Offline D. Tiller

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Re: Tiller Changed, Help me understand why?
« Reply #16 on: May 06, 2009, 03:58:20 pm »
Had my bow at the TN classic change tiller after I shot it a few times.  Was 50# at 27" and then one limb became much stiffer than the other. So I think I will flip the bow and shoot it in on the other side for a few shots to see what happens. If it does not even out I may just re-Tiller it a bit at lower weight or make the stiffer limb the bottom one and use it like and english longbow to get a bit of loft out of it.

What do you all think? Is this a good way to deal with the problem?

Tiller
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Offline George Tsoukalas

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Re: Tiller Changed, Help me understand why?
« Reply #17 on: May 06, 2009, 07:37:03 pm »
I know, Art. That's done on the t tree or the mirror for me and at full draw. :) Jawge
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Offline RT

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Re: Tiller Changed, Help me understand why?
« Reply #18 on: May 06, 2009, 08:41:47 pm »
Thank you all for the advise and insight on tillering these bows.

Yes, i do pre-tiller my two pcs of boo lams prior to glue up (approx 1mm for every 10" out towards the tips) as well, believe me you save a lot of work after the bow has been glued up to it form.

Tillering is a lot of exercising the bow on the tree and only little wood removal  and adjustment is required during tillering.
I have learn lots from the inputs and will inplements these pointers on the next bow i built and see how things goes.

Happy building and great huting guys.................RT  ;D
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Yahoo chat ID : robt188

DCM

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Re: Tiller Changed, Help me understand why?
« Reply #19 on: May 07, 2009, 09:31:06 am »
IMHO "working" a bow on the tree, or "working in" adjustments is not only a waste of time, but actually works against you.  I only bend a bow far enough to see a flaw in the tiller, frequently doing most of the work at brace height.  I don't "work" a bow until the tiller is nearly finished, usually no sooner than around 20" of draw and then only just enough to detect a need for changes.  Working a bow prematurely, while any flaws exist, simply sets the weak wood unecessarily.  Better to get it all bending even, with as little work as possible, THEN, work the bow.  Preferrably by shooting with the aim of fine tuning the timing and while paying acute attention to where the limbs take set.  These areas are weak, whether the static tiller reveals it or not. 

I admit this may be an advanced technique, although I see lots of bowyers who should know better by now still advocate the "working in" adjustments dogma.  The only advantage I see to the practice is it helps the the bowyer make the draw weight he set out to.  But most frequently, unfortunately, making cast like a 10# lighter bow because the weaker wood has already been thorougly crushed and the bow has to drag this dead weight around for the rest of it's life.  I wait until I get nearly to full draw (ie. 25" draw) leaving an extra 10# on the bow, then reduce the weight at the end if necessary.  More often than not, the last 10# will pull out while shooting the bow in, from 25" to 28" draw, without any more wood reduction.

Shoot a bow your are making through the chrono at 25" draw and 10 gpp, then at 28" once it's "worked in" and you'll see the difference it makes.  It can be a real eye opener.  Wish I could figure out how to keep a bow "fresh" all the way up to full draw.

Offline artcher1

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Re: Tiller Changed, Help me understand why?
« Reply #20 on: May 07, 2009, 10:11:42 am »
Well put David. I hope others take notice.

ART B

Offline NOMADIC PIRATE

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Re: Tiller Changed, Help me understand why?
« Reply #21 on: May 07, 2009, 02:01:42 pm »
Absolutely David, .......I try have everything the way I want it at 18" max,    from then on is all about reducing weight and shooting at least 50 arrows every 1/2" increments, I found that overall set decreses a lot by slowly incresing draw length with lots of shots at every stage,....give the wood time to learn  ;D
NORTH SHORE, HAWAII

Offline George Tsoukalas

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Re: Tiller Changed, Help me understand why?
« Reply #22 on: May 07, 2009, 02:25:13 pm »
DCM, I constantly work in changes at short pulls on the tree and in my hand. How else would I know that the change has registered and that I've removed enough wood? Of course, you shouldn't pull a bow further than it takes to expose a problem. Of course, the bending problems should be taken care of early without forcing the bow when possible. That's a separate issue. But bending has to be done to tiller the bow. Changes have to be registered.  I should also mention that I don't even hit target weight until 25 inches for my 26 inches of draw. Working on getting the brace tiller to look good is ok for most staves bit I've made bows were looking at braced tiller was no so useful. Y'all must be working pretty pristine staves. Check this bow out. :) Jawge
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DCM

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Re: Tiller Changed, Help me understand why?
« Reply #23 on: May 07, 2009, 03:06:10 pm »




George,

We have a fundamental difference in how we approach bowyering.  I'm not suggesting any way is "wrong," only that my rationalizations work for "me."  That's why I'm (usually) careful to preface comments with In My Humble Opiion, etc.

My pov is wood bends primarily based upon how thick is it, then how wide.  In addition wood may bend more freely if it has been crushed, even despite it's apparent thickness.  So, when you first crush part of the limb with excessive working, when you later release other "fresh" wood into the equation by reducing it's thickness, you must then set or crush that wood to match the part which started bending earlier.

And yes, it works for knarly stuff too.  Rarely do I build a bow which doesn't have some feature, perhaps 1 in 10, and some are downright folly.  Twist and whoop-d-dos in particular challenge ones patience.  But I still practice and stand by my philosophy, even on the knarly stuff.

Offline George Tsoukalas

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Re: Tiller Changed, Help me understand why?
« Reply #24 on: May 07, 2009, 03:34:51 pm »
DCM, it's ok that we disagree. It's ok if you say the working in method is wrong. I wish I were 1/2 the bowyer you are. I am not suggesting that the stave should be worked in with belly crushing pulls but with short draws of 5-8 in. Change is going to get worked in eventually. I'd rather it be sooner rather than later. I do tiller gently. I don't even hit target weight until I get to 25 inches for my 26 inch draw. I still submit that what a bow does at brace is not always an adequate reflection of full draw but I do aim for good tiller at brace. :) Jawge
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DCM

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Re: Tiller Changed, Help me understand why?
« Reply #25 on: May 07, 2009, 03:42:34 pm »
"I do tiller gently."

This is the core idea.  We're probably saying the same thing with different words George. 

Offline George Tsoukalas

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Re: Tiller Changed, Help me understand why?
« Reply #26 on: May 07, 2009, 05:12:16 pm »
DCM, I suspected so but good things come out of perceived disagreements as long as it is done in respectfully. I liked it when my students challenged me. Now here is what I got out of your comments and several others on here. I would like this clarified. You set up a good tiller at brace and then yank it back to full draw as if you were building a fiberglass bow. Is that true? :) Jawge
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Offline Granite Mtn

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Re: Tiller Changed, Help me understand why?
« Reply #27 on: May 09, 2009, 09:24:43 am »
After building hundreds of bows the last twenty years,  the most valuable tool for tillering is my full legnth mirror, follwed by my wife with digital, followed by dim witted, fairly strong, friends. Tiller trees may have their place, for some but use them in conjunction with other methods.  Especially floor tillering, constant taper, and dim witted friends.

Offline Granite Mtn

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Re: Tiller Changed, Help me understand why?
« Reply #28 on: May 09, 2009, 09:39:53 am »
Boys we have reached the golden age of wood bow making.  The tiller, speed, dependability, beauty, and rapid exchange of information and oppinion has not been rivaled in history. just food for thought.
God Bless,
Chris Blank

Offline George Tsoukalas

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Re: Tiller Changed, Help me understand why?
« Reply #29 on: May 09, 2009, 10:21:12 am »
Granite Mtn, I agree about using the mirror and the digi cam. Now there's an interesting concept- tillering a selfbow with a digi cam. I use it. BTW a window with shades or curtain open works like a mirror at night. Sometimes I feel a little guilty about using these modern tillering tools. Watching my shadow while drawing outside gives a good idea of tiller as does short pulls while holding the stave over my head though I must admit that's not the safest practice. LOL. Interesting that you think this is the golden age of the selfbow. You could be right; with the internet we can help a lot of people get started making bows. :) Jawge
Set Happens!
If you ain't breakin' you ain't makin!