Limb Stability

[Big Ed]

Very cool post!!!

[Lee Robinson .]

Agreed.

[Sixby]

Kirk: limb alignment is critical too.

1 highly underlooked factor.

 I get bows to work on and cannot believe how bad some of them are when it comes to the very basics.
That string should absolutely deadline the center of the bolts on a takedown dead center the limb completely to the tip. anything else is an inferior bow. Period.

there are so many factors that make a great bow. All or most of them are neglected or are approached with pre-concieved attitudes by many bowyers.

 Core is another one. contrary to what so many bowyers say. Core makes a difference. sometimes a very great difference. I hear statements like you could use air for a core if you could get it to hold the glass together, it just makes no difference.

For some reason those same bowyers will say speed makes no difference. Why???(Rhectorical question)

Because they do not want to or do not know to pay attention to the details like Bob Morrison is doing and like Kirk is doing and Zipper and so many other really good bowyers. The old saying,. The Devil is in the details can be used to apply to this subject we are on. I would change that to say that the Greatness is in the details though.

I believe Turkeys asked who are we trying to impress? I would say me. When I do that them it makes me happy.Get by or good enough are two things that will never be heard in my shop.

God bless you all, Steve

[Turkeys Fear Me]

Originally posted by Sixby:


I believe Turkeys asked who are we trying to impress?

Actually Sixby, that isn't really what I said.

What I asked was  how impressive is all this stuff, and what does it really prove?

What I was curious about is what level of limbs would actually stand up to what was being shown in the other videos and pictures that were posted.  It was even implied that it "shouldn't be tried at home" or something along those lines.  I proved to myself that what was being shown could actually be done by a set of cheap $70 limbs.  That's why I asked, how impressive is all this stuff, and what does it really prove?

Not a slam in any way, just a fair question in light of my own testing.  I don't think I ever suggested that design wasn't important, or that performance wasn't important, or that lateral or torsional stability wasn't a good thing.  What I was suggesting is that the tests being used to show those things might not be all that enlightening or remarkable.

[LongStick64]

I was curious about the rigid test that I saw on the KISS site. Everyone of my bows passed the test, Howard Hill, Big Jim, Great Northern, Border, Toelke, EagleWing, Robertson even my Ed Scott........except my Carbon/Foam ILF limbs. So what does that mean......I don't know.

[Sixby]

Peter, What is KISS????
Quite an impressive list of bows that you have there.

God bless you, Steve

[**DONOTDELETE**]

Dear Mr Turkey terrorist,

I'm having a hard time trying to figure out what exactly your are contributing to this thread.    

It wasn't long ago we had a perfectly good debate going on another topic that turned into a  "I didn't say that...."   "What i did say was...." kind of thread and the administers ended up pulling the thread.

i would like to ask you sincerely not to trash out a perfectly good thread here if you would be so kind....

on the other hand if you truly have something to contribute i'm all ears and eyes....

hey Steve.... I've seen some very high end bows that the limb alignment was off on enough that it makes me wonder if the riser actually warped....I could see no way a bow would ever get sent out like that....      
 
i had it happen to me back when i first started building these things and was trying to use solid block risers with no reinforcement.....needless to say it didn't take long to learn to foot a riser after that.

have any of you guys ever had a riser move on you after doing your shelf cut out? or send out a beautifully smooth tracking limb only to have it take a twist later on for no apparent reason?

[Turkeys Fear Me]

Originally posted by Kirkll:
Dear Mr Turkey terrorist,
 

As much as you seem to enjoy making things personal when people have a different opinion than you, I'd rather not take part in that.

Thanks anyway.

[Lee Robinson .]

Originally posted by LongStick64:
I was curious about the rigid test that I saw on the KISS site. Everyone of my bows passed the test, Howard Hill, Big Jim, Great Northern, Border, Toelke, EagleWing, Robertson even my Ed Scott........except my Carbon/Foam ILF limbs. So what does that mean......I don't know.

I would suggest, as a GENERAL (but not absolute) rule, it would mean those bows are more resistant to torque and are inherently stable designs.

Lateral and torsional stability are only two attributes of a bow though. There are many others that are needed to produce a great bow. Some of the bows in your list though are indeed very nice bows (the reason I say some is not to imply some are not good bows...but is only because some of them I am not familiar with).

[LongStick64]

Oopsie I meant  KISA, guess I had 70's rock groups on my mind, lol. I quess what I mean is, is this stability concept more common than perceived.

I have a variety of bows, mostly longbows, and I don't notice any lack of stability, with one exceptions. Two of my Carbon/Foam limbs, longbow configuration on wood risers are in my opinion excessively floppy, and I hate them for it.

[LongStick64]

Just so no one thinks that I don't appreciate ILF longbow limbs. I have a pair of Sky ILF longbow limbs with on layer carbon and wood (bamboo) core that are not floppy and have a stable feel.

[Pepper]

I want a stable forgiving cow, if it is fast, thats just a plus.

[Pepper]

Originally posted by Pepper:
I want a stable forgiving bow, if it is fast, thats just a plus.

[Turkeys Fear Me]

Originally posted by LongStick64:
 I quess what I mean is, is this stability concept more common than perceived.

In my opinion, yes.  That's is why I did my own test with a cheap set of limbs.  Some people took that as me trying to start an argument, but it was really only me seeing for myself, just how common it actually was, and sharing my findings.

 

Originally posted by LongStick64:
I have a variety of bows,   mostly longbows , and I don't notice any lack of stability, with one exceptions. Two of my Carbon/Foam limbs, longbow configuration on wood risers are in my opinion excessively floppy, and I hate them for it.

In my opinion, I think you may have answered your own question.  A traditional "deep core" longbow limb will perform better in Lee's test due to the thickness of the limb.  An ILF longbow is somewhat different in that for the most part, most are basically a thin core recurve limb without the curve. The curve helps in giving a thinner core limb it's stability.  Take away that curve and the limb gets a little whippy near the tips.  You don't have the deep core to give it any rigidity.  Most recurve limbs maintain a wider profile through the curve, giving them their torsional stability.

[Lee Robinson .]

TurkeysFearMe,

I am not at all surprised that your $70 limbs did well. It isn't the cost that determines stability, but design. You can use expensive materials or inexpensive materials and in either case produce either a stable design or an unstable design.

[Turkeys Fear Me]

Originally posted by Keep It Simple Archery:
 It isn't the cost that determines stability, but design. You can use expensive materials or inexpensive materials and in either case produce either a stable design or an unstable design.

I totally agree with you Lee.  That's why I asked the question, which for some odd reason some people took offense to...

"How impressive is all this stuff, and what does it really prove?"

How about vertical versus torsional stability?  Would you agree that  for the most part , a deep core longbow limb will tend to be more stable vertically, whereas a thinner core but wider recurve limb will be more stable laterally?

[**DONOTDELETE**]

Originally posted by LongStick64:
I was curious about the rigid test that I saw on the KISS site. Everyone of my bows passed the test, Howard Hill, Big Jim, Great Northern, Border, Toelke, EagleWing, Robertson even my Ed Scott........except my Carbon/Foam ILF limbs. So what does that mean......I don't know.

Curiosity got me looking for that test you were describing on rigidity and this is what i found.

i don't think it is what you wer talking about, but it was a fascinating article on internal friction in a limb core....

how we could relate this to limb stability is beyond my red neck engineering abilities.  

check it out...

 http://www.primitiveways.com/Bow_and_Arrow_Efficiency.pdf

[Bill Carlsen]

Sixby...sent you an email. I don't understand your response to my post about the Border video and my kudos to Bob M.

[Lee Robinson .]

Originally posted by Turkeys Fear Me:
       

Originally posted by Keep It Simple Archery:
 It isn't the cost that determines stability, but design. You can use expensive materials or inexpensive materials and in either case produce either a stable design or an unstable design.

I totally agree with you Lee.  That's why I asked the question, which for some odd reason some people took offense to...

"How impressive is all this stuff, and what does it really prove?"

How about vertical versus torsional stability?  Would you agree that  for the most part , a deep core longbow limb will tend to be more stable vertically, whereas a thinner core but wider recurve limb will be more stable laterally? [/b]

In terms of the bow itself...the average longbow will generally be more torsionally and vertically stable than a recurve. I suspect the reason a lot of people torque the longbow though is because longbows typically have a less contoured grip. Additionally, most recurves have less shock than most longbows and are also smoother on the draw. Not always, but generally. As a result, while the recurve may be more sensitive to errors, its action and feel may be more prone to promote good form. A longbow (especially the traditional D shaped longbow) may be more forgiving of errors, but its action is generally rougher with more shock and more stack...and therefore is harder for some archers to obtain good form with. In bows, one thing I have learned is many things are a rob Peter to pay Paul situation...and we have to find an ideal balance.

Back to your question...in terms of limb structure, a recurve is generally more ribbon like. The reason for this is the recurve generally has a wider limb and less core and as a result will is easier to flex in either direction. This is also why recurve tends to be smoother on the draw. of course a longbow can be designed that way as well, but when done so it usually ends up being less stable. this is commonly observed in some of the hybrid longbows on the market today. Adjustment can be made to correct this phenomenon though. For example at any given bow lengtg the riser like to be increased and the limb length decreased which increase the torsional and lateral stability of the limbs, but unfortunately increases the level of sensitivity in the riser. we all have different strengths and weaknesses in our form, therefore we all have different preferences. limb core adds to both lateral and torsional strength. it also adds stack as a result and reduces the smoothness of the draw. for example a broomstick is very hard to flex or twist (despite its low cost, haha). This is why we have to find the optimal balance in order to produce a perfect bow for a given archer.

[**DONOTDELETE**]

Originally posted by Turkeys Fear Me:

How about vertical versus torsional stability?  Would you agree that  for the most part , a deep core longbow limb will tend to be more stable vertically, whereas a thinner core but wider recurve limb will be more stable laterally?

That's a good question.... a deep core long bow will have both lateral and vertical strength and stability, but doesn't have the ability to store as much energy as the recurve design.

The wider thinner limbs of the recurve bow need that width for lateral or torsional stability to keep it tracking right without any twist. or i should  say "used to need that width".

Now this might not seem near as exciting to the archer, as it does to a bowyer. but with the composites available to us now. it's made things possible to do things with these limbs that could not otherwise be achieved.

There have been huge gains in limb design in just the last few years by bowyer's all across the nation just by thinking outside the box and utilizing the materials we have available now.

This is the challenging part of designing a recurve limb. as you change the geometry of the limbs shape it stores the energy, and applies more or less pressure in different locations of the limb. a much shorter working portion of the limb is used too. the leverage that hook on the end has, and how much it opens up makes a huge difference on how much width, or reinforcement with the use of composites it needs to maintain stability. it's relatively easy to get your torsional stability with extra width, but the wider you go the thinner the limb becomes and issues with vertical stability come into play.

The ultimate recurve bow would have a deep core, and narrow width that has both torsional and vertical stability.....But.... that one is a tough one to pull off..... we have some nice hybrid long bows out there doing it......but.... we are getting closer all the time finding the ultimate recurve bow....