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Beep Beep Beep Tiller!!!!!!!

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adb:
I never pull heavy bows to full draw on the tiller tree either. Generally, most heavy bows move about 3-5# per inch. Most of mine are closer to 5#/in. If I want a full 32" draw, I would only ever pull it t 30" and, as Will mentioned, shoot it in the last few inches. If your tiller is good at 30", it'll be fine at 32". I also learned this the hard way. I pulled a bow full draw (140#@32") on the tiller to take some pics, and it exploded. Tiller was fine. These heavy bows just don't like being left at full draw for more than an instant. I call the tiller tree 'the merciless extractor of truth'... it's harsh... there is no give, no compression of joints, etc.

toomanyknots:

--- Quote from: WillS on November 07, 2013, 09:21:08 am ---Even if that's the intended draw length.  Most warbow makers don't do it, unless they're photographing it for a customer or something.  If a bow is meant to be 120# at 32", you take it up to 28", work out the projected draw weight at 32" and leave it at 28" on the tiller.  If it makes it to 28" and the tiller is spot on, it'll make it to 32". 

--- End quote ---

I pull my 32" draw bows, whether they are 50 lbs or 130 lbs, usually to 33" on the tiller. I guess I am more merciless than others. (Thats about as heavy as I make though, if I was making heavier, I don't know if I would) If they fail than I will make another. I sent someone a bow one time that was suppose to be 100lbs, but I miscalculated how the weight would stack ( I measured at 28", but made the bow like an inch longer than I usually do), and it only measured 93#, which he wasn't happy about at all, as the first thing he did is measure the draw weight.  ;D On top of my lack of faith in myself to calculate draw weight, I think a bow can loose 5 lbs sometimes just from being pulled those extra 4 inches, so I always make sure to pull and measure at 32", after working the bow in significantly. I wouldn't trust myself and my puny draw to shoot in a bow properly at 32" either.

EDIT: And I got a pulley setup with a block and tackle that I pull by hand, so it is not static or locked or anything. I hate those ones that you crank with a winch, where the bow is stuck, they scare me! If I ever make bows that pull 750 lbs at 38 inches, I think I will just triple up or so on my block and tackles,  ;D.

WillS:
Interesting to hear different approaches!  I think if I was working with a laminate, something that I could glue up again to the same dimensions if it broke I'd probably go right out to 32" as well, just for the "well now I KNOW it's safe" factor, but working with rare, pristine yew staves makes you a bit more aware of the pain when they go boom...

Del the cat:
I calculate as follows.
Say it's 88# @ 28"
28"draw is really 28 minus the brace height. ( A force draw curve pretty much goes to zero at brace).
So if it's a 6" brace the real draw is 22".
Then that gives 88# at 22" which is 4# per inch.
To get from 28 to 32 is an extra 4" and will therefore add 4x4 pounds which is 16# giving 104# @32"
Note:- If you don't subtract the brace hight you'd get 3.14# per inch, giving 100.6# @32"
Del

toomanyknots:
But what about potential stack towards fulldraw? And what about the opposite with reflexed bows? As well as length seems to make a huge difference.

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