Author Topic: Tillering weight drop  (Read 2048 times)

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Offline DC

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Tillering weight drop
« on: January 10, 2019, 12:11:21 pm »
I just noticed that if I hold a bow at a steady position on the tree the draw weight slowly drops. Most of us have noticed this I would think. I have a jam cleat on my tree so I can pull it to say, 20# and lock it down. The weight will start to drop, quickly at first and then slowing down. My digital scale times out after a minute or so but in that time this bow goes down maybe a pound. Is this indicating something that we can use somehow? Is it maybe an indication of how dry it is or maybe how much hysteresis the bow has. I wouldn't want to get in to timing this but if you looked at and thought, "Boy that's dropping fast.", it might tell you something. Any thoughts other than,"You think too much." ;D ;D ;D

Offline Del the cat

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    • Derek Hutchison Native Wood Self Bows
Re: Tillering weight drop
« Reply #1 on: January 10, 2019, 12:22:37 pm »
Like you say, hysteresis... it's the reason that use wood bow archers don't hold at full draw for ages like those compound (spits on floor) guys. Over a day's shooting it turns into string follow and will recover over a few hours unstrung or overnight.
If it doesn't recover it becomes set.
I avoid holding it on the tiller, that's why I use video.
I've had a bow explode at full draw while I held it waiting for someone who was fiddling around with the camera  >:( (Mind it was prob' going to fail eventually, so better sooner than later)
Del
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Offline BowEd

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Re: Tillering weight drop
« Reply #2 on: January 10, 2019, 12:25:14 pm »
I'd say that's pretty much normal DC.I don't make any habit of dong that.That no set tillering sequence seems to serve the purpose of checking the woods integrity that Steve talks about.
Draw weight loss will show itself over time and normal shooting.Some do and some don't.
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline Badger

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Re: Tillering weight drop
« Reply #3 on: January 10, 2019, 01:31:09 pm »
   I have a bow right now that upsets the crap out of me. It drops 5# on the first pull and then stabilizes. The bow performs well but I have never had one just suddenly drop that much. It does the same thing every time it is fresh braced. 1# drop is not bad at all.

Offline IrishJay

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Re: Tillering weight drop
« Reply #4 on: January 10, 2019, 01:53:27 pm »
Another thing to consider is that when your pulling hard enough to move the string you're pulling harder than the bow is pulling back. In order for the string to move the net force on it has to be in the direction of movement. So if you're pulling with 60lbs of force and the bow is pulling back with exactly 60lbs of force net force would equal zero and the string would not move. But if you're pulling with 60lbs and the bow is only pulling back with 59lbs you have a net of 1lb in the direction of draw. What I've observed with my digital scale is that its display is a fraction of a second behind real time. So when you're pulling and the string is still moving the scale reading goes up to 60lbs, but the bow is only pulling back with 59lbs. When you hold the string static you're no long pulling harder than the bow, so you're pull drops to 59lbs to match the bow. It then takes my scale a second or so level off because of the delay.
« Last Edit: January 10, 2019, 01:58:17 pm by IrishJay »
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Offline Badger

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Re: Tillering weight drop
« Reply #5 on: January 10, 2019, 02:39:45 pm »
An interesting test that I haven't done for a long time is to simply hang a 50# weight on a 50# bow and watch it slowly pull the draw length out further. I don't do this test for over a minute, on a good bow it barely moves on some bows it might go an inch.

Offline BowEd

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Re: Tillering weight drop
« Reply #6 on: January 10, 2019, 05:02:12 pm »
That's an unbraced bow pulling on a long string?
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline willie

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Re: Tillering weight drop
« Reply #7 on: January 10, 2019, 05:24:21 pm »
Quote
"You think too much." ;D ;D ;D

I hate it when folks say that. I had a GF once that said "it hurts my head to think" needless to say, we were not a good match.

Quote
Boy that's dropping fast.", it might tell you something.
it might tell you you are doing needless harm to the bow if it drops too much, but then the damage is done :(

one similar thing I like to do when on the "short" longstring is to see how fast,  the string returns to its original position after a pull. I have found that if I hang about a half pound weight on the string before I make the pull, and the string is adjusted well, that I can watch the weight slowly ascend to it's original position in the last few inches. if the rate of return of the last few inches slows down, I know that I am working the belly maybe more than I should.

Offline DC

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Re: Tillering weight drop
« Reply #8 on: January 10, 2019, 05:33:23 pm »
That's an unbraced bow pulling on a long string?
If you're talking to me then yes ;D

Offline Badger

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Re: Tillering weight drop
« Reply #9 on: January 10, 2019, 06:14:25 pm »
That's an unbraced bow pulling on a long string?

  No that is a braced finished bow, I finished it at 51# and it is always at 56# on the first draw. I have never had one drop off that much.

Offline DC

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Re: Tillering weight drop
« Reply #10 on: January 10, 2019, 06:21:08 pm »
 That's weird.