Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calculat

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Ian Turner
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Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calculat

#1 Post by Ian Turner » Thu Dec 22, 2016 2:47 pm

Hi guys and girls,
I have a Hoyt Buffalo which has the Hoyt Formula system for limbs and its a 19"riser.
Trying to figure out if there is any way to work out what draw weight a set of formula limbs made for a target riser of 25" or 23" would be on the buffalo riser an example of what I am trying to say would be say a set of 40# limbs that would make a 68" bow on a 25" riser; what would the draw weight of the bow be if those limbs were put on the 19" riser and indeed would they work or be under too much stress?
Cheers
IAN

shaftcaster
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Re: Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calc

#2 Post by shaftcaster » Fri Dec 23, 2016 9:17 am

Hi Ian,
Not sure if Hoyt has its own formula on this but the general ILF rule is that limbs are rated _ _ _lbs @ 28" on a 25'' riser and that's for Olly type limbs.
Some manufacturers [Tradtech etc Buffalo] rate their limbs on a 17 or 19 " riser and that's for Field/Hunting type limbs.

If then you wish to bolt longer limbs onto shorter riser, however many inches shorter the riser is will usually mean that many more pounds more on the alternate set up.
You would most likely end up around 46# but keep the ILF setting at mid level to be safe [don't try cranking it to max ]

Its a strange logic and took me ages to get my head around it

shaftcaster----

Ian Turner
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Joined: Thu Jan 10, 2013 11:19 am
Location: Sydney NSW

Re: Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calc

#3 Post by Ian Turner » Fri Dec 23, 2016 10:42 am

Hi Ang thanks mate why I am asking is that Buffalo limbs are hard come by and expensive to get but limbs that fit the Hoyt Formula risers fit the buffalo but those risers are generally 23 - 25" so hence my dilemma!
Cheers
IAN

shaftcaster
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Re: Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calc

#4 Post by shaftcaster » Fri Dec 23, 2016 1:25 pm

Ian I do recall hearing that Hoyt ILF is a little different to conventional ILF around everywhere.
Never checked it but heard somewhere, would think that Hoyt onto Hoyt would be fine I assume ??

Ian Turner
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Joined: Thu Jan 10, 2013 11:19 am
Location: Sydney NSW

Re: Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calc

#5 Post by Ian Turner » Fri Dec 23, 2016 2:56 pm

Hi Ang yeah mate they are actually the Hoyt Formula system which is a bit different to ILF and not interchangeable.
Cheers

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Ronster
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Re: Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calc

#6 Post by Ronster » Mon Dec 26, 2016 8:40 am

I own a Win & Win olympic style bow with ILF Limbs, and rule of thumb is the length of the riser makes approx 2+ lb per inch difference.
I am not sure that it works the same for Furmula system, but it would have to be close as it is only a means of attaching limb to riser.
So on that basis you are adding an extra 10+ lb going from 25" riser to 19" riser, and losing 10lb+ going from a 19"riser to a 25" riser.

Ronster
I would love to be an expert, but experience and lack of knowledge holds me back!

Bows:-
Raven Vanquish 62" TD Recurve 44# @ 28"
Beaver 64" Longbow 41# @ 27"
Bear Montana 64" Longbow 50# @ 28"
Win & Win Winact ILF Riser and Win & Win Pro accent ILF carbon foam limbs 48# @ 28"

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GrahameA
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Re: Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calc

#7 Post by GrahameA » Mon Dec 26, 2016 5:06 pm

Hi Ron.
Ronster wrote:I own a Win & Win olympic style bow with ILF Limbs, and rule of thumb is the length of the riser makes approx 2+ lb per inch difference.
I am not sure that it works the same for Furmula system, but it would have to be close as it is only a means of attaching limb to riser.
So on that basis you are adding an extra 10+ lb going from 25" riser to 19" riser, and losing 10lb+ going from a 19"riser to a 25" riser.

Ronster
A suggestion.

On the existing riser measure the bow weight on a reasonbly accurate setup. (Use a setup of the level of accuracy you want.)
Put the limbs on the longer riser, measure the draw weight.
Assume the rate of draw weight change is linear.
You have two points on the linear graph of riser/draw length vs. draw weight. You can fill in the missing points.

Or

Put the existing limbs on the riser and again measure the draw weight at the nominated draw length. (It's a control value.)
Put a set of target limbs with a known/branded draw weight and measure again. That gives you a new draw weight for the Buffalo riser. Assume the rate of change vs. Riser length is linear. Use it to extrapolate an expected value on the different length risers.
Grahame.
Shoot a Selfbow, embrace Wood Arrows, discover Vintage, be a Trendsetter.

"Unfortunately, the equating of simplicity with truth doesn't often work in real life. It doesn't often work in science, either." Dr Len Fisher.

Ian Turner
Posts: 648
Joined: Thu Jan 10, 2013 11:19 am
Location: Sydney NSW

Re: Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calc

#8 Post by Ian Turner » Fri Dec 30, 2016 1:17 pm

Hi Grahame, Ron,
Thanks for the replys; I actually don't have another set of limbs to try your suggestion with as the Hoyt Formula limbs are quite expensive to buy so I was going to try to figure out how they would "convert" from the rated X LBS AT 23" and 25" risers to my 19" riser but also if they would be Ok on the shorter 19" riser without "blowing up".
Cheers and thanks
Ian

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Ronster
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Re: Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calc

#9 Post by Ronster » Fri Dec 30, 2016 8:44 pm

Hi Ian, I don't think that they will blow up, just be a heavier draw, 2-3 lbs/inch.

Ronster
I would love to be an expert, but experience and lack of knowledge holds me back!

Bows:-
Raven Vanquish 62" TD Recurve 44# @ 28"
Beaver 64" Longbow 41# @ 27"
Bear Montana 64" Longbow 50# @ 28"
Win & Win Winact ILF Riser and Win & Win Pro accent ILF carbon foam limbs 48# @ 28"

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GrahameA
Posts: 4691
Joined: Thu Mar 10, 2005 4:28 pm
Location: Welcome to Brisneyland, Oz

Re: Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calc

#10 Post by GrahameA » Sun Jan 01, 2017 6:41 am

Morning Ian.
Ian Turner wrote:... I actually don't have another set of limbs to try your suggestion with as the Hoyt Formula limbs are quite expensive to buy so I was going to try to figure out how they would "convert" from the rated X LBS AT 23" and 25" risers to my 19" riser but also if they would be Ok on the shorter 19" riser without "blowing up".
Keep a lookout for a pre-loved set of limb on AF.

Past experience with 'Warfs' suggest you are unlikely to damage the limbs. That same experience also suggests that whilst you can estimate the change in draw force it is better to test something similiar. :-)
Grahame.
Shoot a Selfbow, embrace Wood Arrows, discover Vintage, be a Trendsetter.

"Unfortunately, the equating of simplicity with truth doesn't often work in real life. It doesn't often work in science, either." Dr Len Fisher.

Ian Turner
Posts: 648
Joined: Thu Jan 10, 2013 11:19 am
Location: Sydney NSW

Re: Hoyt Formula Limbs on a 19" Buffalo Bow - Draweight Calc

#11 Post by Ian Turner » Sun Jan 01, 2017 3:58 pm

Thanks mate.
Cheers

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