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Author Topic: ERC ELB, Tiller Help?  (Read 4312 times)

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Offline Chadwick

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ERC ELB, Tiller Help?
« on: February 23, 2015, 07:36:41 pm »
Hi all. 73" ntn, pulling 35#@25" with an 8" brace height (I tied my tillering string too short, but decided to go with it). I'm going to knock the tips off to put on buffalo nocks, so it will finish to maybe an inch shorter ntn. This is a piece of ERC which I don't want to back, and don't see a need to yet. Hoping for 50#@30".  My last ERC blew because of belly chrysals, so this one will have a flatter belly. Any comments on the bend?
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Offline sleek

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Re: ERC ELB, Tiller Help?
« Reply #1 on: February 23, 2015, 07:53:02 pm »
Thats an even bend between the limb. I dont know if you will reach 50# though. It sure is a nice lookin bit of wood. I admire your craftsmanship.  Id add though, I really think the entire outer 1/3 of the bow isnt bending enough. Bring your tips around more to evenly strain the wood. You may get 40-45# after that because your gonna take up lots of draw length getting those tips bending more.
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Offline Chadwick

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Re: ERC ELB, Tiller Help?
« Reply #2 on: February 23, 2015, 08:05:56 pm »
Thank you, I'll work on the outer thirds. I've already got it tapered to go into the horn nocks, so I'll do some bending tomorrow after the glue sets up.
I think I'll make sure that the moose rack is in all of my tillering photos.  :)
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Offline Zion

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Re: ERC ELB, Tiller Help?
« Reply #3 on: February 23, 2015, 08:27:23 pm »
it'd be good to see unbraced as well
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Offline PEARL DRUMS

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Re: ERC ELB, Tiller Help?
« Reply #4 on: February 23, 2015, 08:33:40 pm »
Spooky! I think it looks alright. I wouldn't let the handle move anymore at all. Id focus on getting the mids coming around a fuzz.
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Offline mwosborn

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Re: ERC ELB, Tiller Help?
« Reply #5 on: February 23, 2015, 08:48:24 pm »
Looks like it is bending nicely.  At 73" and bend through the handle hopefully you can make 50# - my 68" stiff handle blew on me at about when you are now - yours looks better than mine did!  Good luck - love to see it finished!
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Offline Chadwick

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Re: ERC ELB, Tiller Help?
« Reply #6 on: February 23, 2015, 11:59:14 pm »
Other than final sanding/shaping, I'll leave the middle alone... maybe even build it up slightly! When I looked for my buff horn for tips, I grabbed an old (as in 100s of years) whale rib bone instead and cut/drilled/sanded out some tips. They're glued on and I'll shape a bit more tomorrow. It's semi-rainy here today & tomorrow, so I'm hesitant to do final tillering. Have any of you found daily weather patterns to be important, or does it take weeks?
Here's an unbraced picture, goes back to mostly straight.
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Offline sleek

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Re: ERC ELB, Tiller Help?
« Reply #7 on: February 24, 2015, 12:14:30 am »
With that little joggle in the right limb I would make it the upperr limb as it will be less stressed with an even tiller. The lower limb typically is the limb that bends the most with the arrow above center because there is more leverage on it. So with an even tiller like you have the upper limb will be weaker than the bottom as it should be and you still get an even looking tiller.  I say the upper is weaker because it natually bends unbraced towards the string some.
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Offline Josh B

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Re: ERC ELB, Tiller Help?
« Reply #8 on: February 24, 2015, 09:41:07 am »
You got it backwards Sleek.  I'll grant ya that it seems counterintuitive, because we naturally think in terms of energy storage and a longer draw at a given weight stores more energy.  But think of it in terms of tip travel. If you have a symmetrical appearing full compass tiller on a bow that has one deflexed limb.  The deflex limb doesn't have too bend as far to balance with the straight limb at full draw.  That means the deflex limb is stronger.  Put it on the bottom. 
The tiller looks pretty good to me. The left limb looks spot on. The right limb could use a few scrapes mid limb, but not much.  Nicely done so far.  Josh
« Last Edit: February 24, 2015, 09:59:18 am by Gun Doc »
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Offline sleek

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Re: ERC ELB, Tiller Help?
« Reply #9 on: February 24, 2015, 12:42:23 pm »
Thanks for the correction doc.
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blackhawk

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Re: ERC ELB, Tiller Help?
« Reply #10 on: February 24, 2015, 12:52:00 pm »
You must be feeling frisky going unbacked ..  ::)

Looks like you reduced the sapwood? Decrowned,or followed a ring? And do i see some heartwood on the back in the right limb?
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Offline TimBo

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Re: ERC ELB, Tiller Help?
« Reply #11 on: February 24, 2015, 12:57:29 pm »
Sorry if this is thread hijackery, but I really want to learn more about tillering by feel, and this deflex limb question interests me.  If the deflex limb in Gun Doc's example is stronger, won't that be something you would feel?  And if you felt it, wouldn't you weaken that limb so the bow felt balanced when you were drawing it?  Isn't feeling proper balance between the limbs more important than having them visually match at full draw when one is more deflexed or reflexed?  You know a lot more about it that I do, but this point has always confused me a bit.  (And it does apply to this bow, so hopefully I am not hijacking too much!)

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Offline Josh B

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Re: ERC ELB, Tiller Help?
« Reply #12 on: February 24, 2015, 01:19:43 pm »
Oh my!  I didn't see the heartwood on the back with my little phone screen.  That scares me a bit.
Timbo good questions.  You are absolutely correct, the bow should feel balanced in the hand throughout the draw.  In this case the deflex (stronger) limb will work in the bowyer's favor.  As sleek mentioned, the lower limb is under more strain than the top limb.  So having a 1/2" or so deflex in the lower limb does the same thing as a positive tiller with the added benefit of a more appealing symmetrical appearing full draw.  Josh
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Offline Chadwick

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Re: ERC ELB, Tiller Help?
« Reply #13 on: February 24, 2015, 01:41:21 pm »
Yeah, I reduced the sapwood. The heartwood creeps up several growth rings near a knot, but isn't quite to the back. I might put rawhide on it after all, but I don't think that rawhide would make the difference between breaking or not, just whether or not the pieces are connected by rawhide. I appreciate the commentary about tillering even tiller, but then making the more deflexed limb the lower limb. It would indeed be stronger if it's the limb which travels less.
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Offline TimBo

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Re: ERC ELB, Tiller Help?
« Reply #14 on: February 24, 2015, 01:43:13 pm »
Ah, OK - that makes sense.  I have tried to leave the lower limb a little stronger when going by feel, so I should have been able to put that together in my brain...thanks for the explanation! 
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