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Author Topic: String lift off  (Read 2750 times)

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Offline DC

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String lift off
« on: February 19, 2016, 02:47:03 pm »
I'm tillering a boo-yew recurve and I noticed that one limb lifts off before the other. One is at 11" and the other is about 13". Is this something to be concerned about? It's room temperature cured epoxy and I glued in some Perry reflex so I'd rather not heat it. I'm pulling it 17"@40# right now I'm shooting for 45#@28".
Thanks
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Offline PatM

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Re: String lift off
« Reply #1 on: February 19, 2016, 02:58:08 pm »
That's part of tillering and  "timing" and whether you notice it personally in the shooting characteristics of the bow.
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Offline DC

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Re: String lift off
« Reply #2 on: February 19, 2016, 03:02:40 pm »
I don't want to open the timing debate again but how would that manifest itself? Hand shock or????
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Offline bow101

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Re: String lift off
« Reply #3 on: February 19, 2016, 03:27:32 pm »
Only time I ever got hand shock is from overly thick or heavy tips.  Can timing be perfect 2-3 years down the road..? I question this with wood bows.
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Offline Badger

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Re: String lift off
« Reply #4 on: February 19, 2016, 03:46:14 pm »
 When you draw it back your handplacement affects how they lift off. You want them to lay back down evenly when the arrow is being released, your hand will be gone at this point. If it is off you will see the arrow slightly porpoise possibly. You can play with the nocking point and even the height of the arrow rest to tune it.
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Offline bow101

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Re: String lift off
« Reply #5 on: February 19, 2016, 03:50:27 pm »
Quote from: Badger on February 19, 2016, 03:46:14 pm
When you draw it back your handplacement affects how they lift off. You want them to lay back down evenly when the arrow is being released, your hand will be gone at this point. If it is off you will see the arrow slightly porpoise possibly. You can play with the nocking point and even the height of the arrow rest to tune it.
Yep nothing like fine tuning.  Good point about "your hand will be gone at this point"
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Offline DC

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Re: String lift off
« Reply #6 on: February 19, 2016, 03:56:54 pm »
Quote from: Badger on February 19, 2016, 03:46:14 pm
When you draw it back your handplacement affects how they lift off. You want them to lay back down evenly when the arrow is being released, your hand will be gone at this point. If it is off you will see the arrow slightly porpoise possibly. You can play with the nocking point and even the height of the arrow rest to tune it.

So if I move the bow right or left on the tree I should notice a change in lift off?

" If it is off you will see the arrow slightly porpoise possibly."  This is the kind of answer I was looking for. Something I can look for.
Thanks
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Offline bubby

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Re: String lift off
« Reply #7 on: February 19, 2016, 04:18:29 pm »
Dc are you far enough along to start slinging arrows, if so film the release and watch what happens
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Offline DC

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Re: String lift off
« Reply #8 on: February 19, 2016, 04:42:15 pm »
Not quite, maybe the rain will let up by the time I'm ready.
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Offline DC

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Re: String lift off
« Reply #9 on: February 19, 2016, 05:05:27 pm »
I went back to the shop and took a close look. I figured that the limb that was lifting last (top limb) must be straighter so I decided to check the +- tiller. I had about 1/2" negative. (I think I said that right.) Anyway, I evened it out so I have neutral tiller. Presto!! String lift off is the same on both limbs. Now, in hindsight, everyone's posts make sense. I'm now at 20"@ 40# so I could fling a few arrows but I would drown out there.  ;D ;D ;D
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Offline bradsmith2010

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Re: String lift off
« Reply #10 on: February 19, 2016, 08:10:55 pm »
I think the same thing happens with a straight tip bow,, we just can't see lift off, but the timing is affected in much the same way,,if the tiller is off,, :)
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Offline simson

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Re: String lift off
« Reply #11 on: February 20, 2016, 04:01:52 am »
DC control the angle of the hooks/levers, sometimes one let go.
Also control your pivot point, a change here changes the tiller!

Positive tiller - asym. bow
Zero tiller - sym. bow

I make most of my statics asym. with pos. tiller - with matching string lift off.

Don't trust the tiller tree, lot of factors to watch

Just my thoughts ...
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Simon
Bavaria, Germany

Offline Del the cat

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Re: String lift off
« Reply #12 on: February 20, 2016, 04:32:19 am »
Gotta see how it is in the hand.... no one actually shoots off the tiller! >:D
Del
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Offline Springbuck

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Re: String lift off
« Reply #13 on: March 03, 2016, 05:10:12 pm »
  This is one reason I like making recurves with string bridges.  I can tune this just a bit by moving the bridge or making one slightly higher than the other.
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