Draw force curves.... anyone?

I'd really appreciate it if all you archers with draw force curves for their setup out there could find the time to email them to me.

I'm trying to get some real data on the limbs in use at the moment. I'll then share all info with you by emailing a pdf including all I receive.

Thanks in advance
John

[WhitehartFB]

So far I have put most of the popular limbs through the Easton BFM kit using38lb/68 up to 31" draw and you will be surprised to learn that all the popular limbs have very similar DF curves, without labels you would be very hard pushed to pick out the difference between Challenger, G3's, SF, Winex to name a few. Yet each pair have their own distinctive feel, shooting characteristics and balistic fps results.

If anyone is prepared to share info I'd be obliged ...cheers

[Kae]

Originally Posted by McCaig

If anyone is prepared to share info I'd be obliged ...cheers

Its not that I don't want to share, I just don't have the information to give you! Unfortunately scales capable of producing draw force curves are expensive and the majority of us won't have access to them, me included.

Kae.

Thanks kae, I know you would share if you had the info I also fully understand that retailers may have commercial reasons for not sharing

[ThePinkOne]

Personally, i think the limb and bow feel is more subtle than the DF curve will show....

I have 2 Equalizers. Identical spec. Set up very carefully- same peak, let-off and DL. One has replacement limbs. However I can still tell them apart- one draws slightly sweeter than the other. Even with the cams set the same. However, although I can feel this, Kev down at WAS (who also shoots a Bowtech) has shot both and cannot tell the difference. Reality is, the difference is so small that unless you shoot them alot (i.e. every day) you cannot really tell.

Hence I suspect that the variations in limbs that make an archer choose one over another because they like the feel of one are very small- and probably not really detectable within the error margins of plotting DF curves.

JMO though.

It's the last 3 inches on a recurve limb graph from 28" - 31" that I'm specifically interested in as I've heard that some limbs only show a modest increase in weight in this range and was wondering if this was true

Has anyone else heard about this?

[geoffretired]

I think I am talking about the same thing here.
Some bows were described as "stacking", when I shot recurve years ago. It meant that in the last inch or two of their draw, they became rapidly stiffer.
I suppose those bows that didnot suffer from that would have increased more gently, or had a more modest increase. I know recurve archers who still talk about this and say that their new limbs feel lighter or easier to pull than their other ones. I imagine this is caused by the same thing; a more modest increase at or near the 28" part of the draw.

Originally Posted by geoffretired

I think I am talking about the same thing here.
Some bows were described as "stacking", when I shot recurve years ago. It meant that in the last inch or two of their draw, they became rapidly stiffer.
I suppose those bows that didnot suffer from that would have increased more gently, or had a more modest increase. I know recurve archers who still talk about this and say that their new limbs feel lighter or easier to pull than their other ones. I imagine this is caused by the same thing; a more modest increase at or near the 28" part of the draw.

Yes, the area I'm interested in is the rate of change of poundage over drawlength for the range 27" - 31" as a low rate should give a very smooth draw through the clicker. there may be limb stabilty problems associated with a limb like that though, but at the moment I don't know if these types of limb even exist, if they do it would an advantage to know which were smoother at the top end don't you think?

[ThePinkOne]

Originally Posted by McCaig

Yes, the area I'm interested in is the rate of change of poundage over drawlength for the range 27" - 31" as a low rate should give a very smooth draw through the clicker. there may be limb stabilty problems associated with a limb like that though, but at the moment I don't know if these types of limb even exist, if they do it would an advantage to know which were smoother at the top end don't you think?

If you look at some of the theory of limb design (eg in the Bowyer's Bible) I think you'll find that the angles and design of the recurve indeed effects the DF curve, as does the material to some extent.

In an ideal world, the limb is designed so that the recurve part is coming in to the correct alignment as full draw is reached- similar to a bow with siyahs coming into optimal leverage position. (I'm not describing this very well, sorry). So you ger max cast but no stack. However, in the world of mass-produced limbs we don't design the bow to the archers DL, we have 2 main riser and 3 main limb lengths plus a series of slightly different limb profiles from different manufacturers. Just looking at averages, there is likely to be a combination that suits you somewhere.

Limb design is also a compromise between speed and stability. The Turkish flight bows were fast and short, but also very critical to shoot... the mongolian/chinese versions were longer and more stable but not so fast. As with so many things in life there's no such thing as a free lunch with limb design...

P.