Primitive Archer
Main Discussion Area => Bows => Topic started by: Lee Lobbestael on May 15, 2014, 11:15:58 pm
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Can somebody please fill me in on why you would decide on a molly design? What are the benefits of it? I have never made one but they seem to be popular on here lately. I try to get the entire limb (minus a few inches at the tips) working. It seems to me that this minimizes the stress at any given point and reduces set as well as prolonging the life of your bow. With the molly design it seems to me like you are purposely concentrating the stress on the inner limbs. Can someone explain what I'm missing here?
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Well for starters, the inner limb doesn't bend a whole lot more on a molle than on a full working limb bow. Think of putting a long stick on the tip of your finger: you only have to bend your finger a tiny bit to move the tip of the stick ten inches. Now make that stick very stiff but light and compare using it to propel something stuck on its end to propelling something stuck on the end of your finger.
The advantages are still up for debate, but all my fastest bows per draw weight have been mollegabets. The idea behind mass efficiency is that if you make a narrow, thick lever it can be lighter than a wide, thin working limb, and therefore reach higher speeds in the same distance. String angles are also less severe, and those light levers translate to low/no hand shock.
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Hey thank you that makes alot of sense! I should try one one of these days but I just love the look of a good tiller on a flat bow.
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Maximally stressing a piece of material is better use of it from an efficiency standpoint. Stressing the whole limb to a lesser degree is not.
A Mollie is the first step towards a static recurve which is a more efficient bow than a straight bow.
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Maximally stressing a piece of material is better use of it from an efficiency standpoint. Stressing the whole limb to a lesser degree is not.
A Mollie is the first step towards a static recurve which is a more efficient bow than a straight bow.
I was able to keep a string on some recurved molle tips, but it was only because they were too thick and they pretty much defeated the whole purpose of the mollegabet. Know of any properly recurved mollies?
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A good thread, ripe for discussion I've not made one yet for much the same reasons.
Reduced mass in the outer third is easilly acheived without going to a full Molly... and yes we do see a few with Mollys from newbies with ends that could hold up a Cathedral roof (AROOGAH AROOGAH exageration alert ;D )
DO we find Mollys in flight records? Anyone got fps figures for like for like wood, draw length/weight of Molly vs other styles.
Prob a silly Q as I'd guess that any optimally made bow in almost any style would give similar performance.
Del
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I'm sure some are waiting for me to chime in on this with my experience on making countless lever bows..BUT not sure if I wanna engage on this one as I see several quotes from a few different folks that can easily be debated and dispelled ...and it might get quite lengthy in my explanations to do so..sorry just don't wanna go there right now...I've made enough now to know the pros and cons of them,and what's fact and fiction :-X
How about you make a few dozen of different kinds,styles,woods and make up your own conclusion :-X
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Man I thought we were gona get to read the book ! :( :( :( >:D
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I'm sure some are waiting for me to chime in on this with my experience on making countless lever bows..BUT not sure if I wanna engage on this one as I see several quotes from a few different folks that can easily be debated and dispelled ...and it might get quite lengthy in my explanations to do so..sorry just don't wanna go there right now...I've made enough now to know the pros and cons of them,and what's fact and fiction :-X
How about you make a few dozen of different kinds,styles,woods and make up your own conclusion :-X
You big tease... I've met girls like that >:D ;) :o
Del
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I'm sure some are waiting for me to chime in on this with my experience on making countless lever bows..BUT not sure if I wanna engage on this one as I see several quotes from a few different folks that can easily be debated and dispelled ...and it might get quite lengthy in my explanations to do so..sorry just don't wanna go there right now...I've made enough now to know the pros and cons of them,and what's fact and fiction :-X
How about you make a few dozen of different kinds,styles,woods and make up your own conclusion :-X
You're more than welcome to express your conclusion. I would hope this wouldn't tun in to another pissing match. If it does , ....... Don't fall into the trap. The primary purpose of this board is information sharing ,I believe.I value your input and I'm sure I'm not alone.
I think the real task of testing these theories ,is that most of us don't tend to build comparable bows and keep them around. I'm in the ugly predicament right now of not having a real nice hunting bow for myself. :o
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I made one about 20 years ago when I first heard of them, they were called Holmegaards back then. The one I made did not have the extraordinarily long levers of some of the ones I see people making these days. I certainly was not impressed with the bow, to the point where I never made another. They are unique looking though and if I was to ever make another I certainly wouldn't make it with those long levers.
As an aside, there was a study done many years ago and the person, I believe it was O.L. Adcock, found that performance was maximized when the last 6" to 8" of the limbs were non-bending. I would think that this would apply to Mollies as well.
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Blackhawk has shown many "recurved mollies" that presumably work very well . I guess the argument might be that they don't perform better than other styles.
The best way to think of a recurved mollie is as a bow with siyahs.
The best way to make one is to splice in the tips with the wood turned on edge to maximize the bending stiffness per mass.
The studies Kooi did showed that a lever tipped bow with a lower angle of 35 degrees is the most efficient bow.
That's a recurved Mollie.
The beautiful bulletwood laminated skeleton tipped bow made by David Brunetta a few years ago essentially fits this criteria and holds a flight record.
I think where many people fail to explore the potential is by making the bow too light in draw weight relative to the mass of the outer limbs.
There is a tipping point there which is similar to that seen in hornbows.
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In one of the above posts they were talking about stresses being more in a molly at certain places. truth is all bows with any design should have about the same amount of stresses. The streses are controlled by strategicaly ballancing the width and thickness of the bow with the amount it is bending. We know we get this right when we are not taking set in our limbs. I feel like mollys are a good design and will probably have a place in flight shooting with light arrows even if they haven't so much yet. The logic behind the molly bow is seen in almost all flight bows, narrow stiff outer limbs.
Just talking self bows the recurves and the r/d bows with reflexed limbs will usually edge out the molly in speed if they are made properly. A lot of us employ the molly technology into our r/d bows by making hte outerlimbs stiff and narrow even if it is not as exagersted as we see in a lot of pure molly bows, same physics are still apllying. From what I have tested which is probably hundreds of bows over the years a regular straight american long bow with no string follow and properly made will usually hit about 172 fps, a real well made molly maybe 175 fps, an idealized r/d bow about178 fps and recurves up to about 182 fps. The great majority of all these bows are lower than these numbers. This is talking 10 grains per pound and 28" draw.
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Thanks for picking up "some" of the slack Steve 8) and when you start curving the levers it can easily be classified as a recurve and be in the same class as them ...also giving them a r/d shape seems to enhance them as well... I'll post some links of my better ones n such here in a few minutes..gotta eat first
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the book is coming !!
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Here it is...my big long explanation and conclusion....drum roll please!!!!
The nut holding the drawknife plays the biggest factor more than anything else!!! 8) :-X
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Trying to think of a reason why I've been trying them .
Best reasons I can think of is :
I like the way some of them look ( those that have that almost half circle in the working limbs)
I want to try different styles of bows ( want to build more than just one or two styles , I know several folks that build recurves and standard self bows and that's it )
I like making shavings ( stress relief )
Because its there ? ( sounded good )
Or maybe it's like Blackhawk said ( the nut behind the drawknife )
Well whichever sounds good to you is my reason .
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Here it is...my big long explanation and conclusion....drum roll please!!!!
The nut holding the drawknife plays the biggest factor more than anything else!!! 8) :-X
DRUM ROLL!!!!!!!!!!!!!!!!!!!!!
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Hmm? How to say this modestly in humbleness?
I think its safe to say that I've played and experimented with the lever bow designs as much as anyone else in the last few years,and maybe in our modern times(last decade etc..),and trying to find the best way to execute them, and to tweak and perfect them to the highest levels possible with them...I've tried lots of different ratios of percentage of lever to working limb,countless wood species,boards,staves,laminates,stiff handles,bendy handles,really short lengths,super long lengths,straight levers,slightly reflexed levers,curved levers to full on big hooked static levers,straight working limbs,deflexed handle,R/D,etc etc...you name it and I've tried almost everything you can concoct and imagine,and configure into a lever style bow...and I still haven't quite come to a end all ends conclusion either with em(and never will either)...but I think I've gained enough ground to say I've got it narrowed down pretty good.
Here's a few of my favorites that not only just shoot fast,but also score very well in all the other categories of what makes a good bow a good bow(to me at least IMO)..which to me these days adds up more and is worth more than speed alone...notice the similarity in all of them.
http://www.primitivearcher.com/smf/index.php?topic=42911.0
http://www.primitivearcher.com/smf/index.php/topic,36920.0.html
http://www.primitivearcher.com/smf/index.php?topic=40916.0
http://www.primitivearcher.com/smf/index.php/topic,38078.0.html
Where I'm at right now is that I like my lever to be around 33-40% of the length of my limb...it seems to be the "sweet spot"..and less and you don't get enough leverage dynamics,and anything longer seems to be like a 2 year old trying to swing a major league sluggers bat for a lack of better terminology...which in most bows ends up being 8-10" long or so on average...and I like the first couple inches of my levers to "give" at or near full draw..that way I still have leverage from them,AND they are as light as possible in mass...and reflexing or curving them helps "stiffen them"(meaning maybe a lighter lever yet) and when they give a lil they still maintain a better and lower string angle than a straight lever....the above bow links I posted all have a similar degree of curve as well...~35-45°...which is funny cus patm mentioned another's study finding the same results as my hillbilly bow making ways...also another thing is if the first couple inches give then only 6-8" are really stiff and also coincide as to what Marc mentions...and if done right you now have a really low mass outer half of your limbs..more so than a lot of other designs...and if done right this is why and how this design can really shine...but that's the hard part for 90% + of the folks I see out there trying to make them...like I said...it pretty much has more to to with the nut holding the drawknife...
Also to add onto what Steve said in incorporating the skinny stiff leverage tips into other designs really gives them leverage almost in the same way...I pretty much now incorporate that into a lot of my bows regardless if its a "molly" or not.
Ironically and funny enough is the similarity of some of my favorites to a Turkish horn bow...its almost like a self bow form of one ..meaning its a lil longer,slightly wider limbs,less setback limbs etc so that it survives as a bow because we know that unbacked wood can't take and match the elasticity limits of sinew and horn...and they also seem to be like a horn bow in that they tend to do better and shine brighter in heavier weights like over 50 pounds..although a lighter one will still do well enough,but it just seems like there is little difference between a 40 and 60 pound bows levers mass wise(even when both are made right),and we all know the 60 pounds is gonna throw that stiff armed lever harder than the 40 pound one...
OK..I'm outta wind...
End of chapter one!!!
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That pretty much sums it up perfectly.
It gets even more interesting when you step them up past that 60 pound mark. That's when you can really see the benefit of the little league bat ends combined with the Babe Ruth inner limb. ;D
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Blackhawk says it better. He has more posted, too, so I'll keep following his example ;)
I especially like that BL molle, looks almost like my few 'ideal' molles I've made though I confess I almost always shy away from recurving the levers :-[
All my favorite molles have been over 45# and had no room in the tips for side grooves with just a touch of bend at full draw (not enough to crush the itty-bitty belly). I still think, and the math adds up, it takes more mass to make a wider outer limb stiff than a narrow one, which is what started me on my first molle and took me deeper into the addiction of bowyery.
Who knows, maybe when I've got the courage to bend the levers I'll have to send something to Blackhawk and see what he thinks ;)
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For sure. Pics are worth a thousand words.
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Ugh, reading this thread is actually making me want to make one. First time I saw one I thought they looked stupid but I saw some at the classic that were sweet looking.
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Good explanation Clint. One thing you said that I liked and agree with 100% is that you cannot get a conclusive answer when working with wood. You can narrow it down pretty close. I would build bow after bow after bow with just slight differerences and not come up with anything really conclusive about which was better, but I could tell what direction it was going. The molly principle is incorporated into most all bows anymore.
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I liberated some demesions from Blackhawk and built a few with that design, plus I've built several standard mollies, and damned if Chris's design didn't make a faster better performing bow, i'll be the first to admit I ain't no Blackhawk but I build a decent bow, and I got an idea what I want out of a bow, i'm going to build some more with the demensions I stole, I mean borrowed from Chris and add some of my own tweaks and see what I can improve, that's the point right, to build the best bow you can cause if you ain't going foreward your going back ;)
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Did I say Clint? I meant to say Chris. I mix up handles with names constantly.
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I've made only one molly, but it was an impressive thing. I want to make more mollies, but I need the right wood and stave for it. I'm still contemplating spliced in tips, made from a lighter wood. Such as hazel tips spliced in black locust, or something similar. I also want to make a bamboo/hickory backed ipé with a reverse tapered tip core laminate out of a light wood. So the ipé gets lost in the stiff tips and the lighter core wood takes over. It ultimately just has to do with lowering the weight in the tips, while maintaining stiffness.
Blackhawk, thanks for the inspiration. I like this kind of summary on a bunch of bows you've made. Of course I could find all these bows, but combined with your short story it helps me to see the similarities in these bows. It certainly saves me a few lousy experimental bows that I would have to make myself if it wasn't for your experience.
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I have one with spliced in bamboo levers (hollow) >:D
I inserted a short wooden plug to solidify it enough to form the v splice and did the same at the very tips to allow the nocks.
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Being newer to this, I've got a couple possibly newbish questions.
Conceptually speaking, don't most woods have a similar "dry-fire" recovery speed? With that in mind the biggest consideration it seems people have mentioned is the importance of having the draw weight high enough to compensate for the levers' displaced load and bring the bow itself back to the full dry-fire speed of the materials. After that point, you're adding performance to the arrow speed and taking advantage of the leverage. Does anyone have higher-poundage versions tested compared to more conventional designs of the same weight? Would the required width to make that poundage be a limiting or at least prohibitive factor? Has anyone noticed a greater advantage to the design with overall shorter bows as well, where the width needed is more feasible? Who wants to tackle the 4"-wide 20% working-limb 50" molly?
Great read, guys. Thanks for the brain food.
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A heavier bow doesn't have to be that much wider and yes an 80 pound mollie does outshoot a conventional design. For me anyway.
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That's very well put Chris. I gotta make me another one. The first one was under weight and one of the first bows I made. I still love to shoot it and it is still shooting. So I like it . But it would be fun to revisit the design :)
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Some like European sports cars, some like American muscle cars. Just drive what you like! :D
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I like this thread and agree with most of whats been said. The only thing I don't like about molly's is the abrupt transition from working limb to stiff outer limb. It just doesn't make sense to me. I think its near impossible to get enough bend out of the last few inches of working limb to justify the width out there. That's why I think the holmegaard design we used to see more often is a better option.
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It's just another fade. If you can make an inner fade hinge, you can certainly make an outer one bend.
Your point is probably more geared towards the way a bowyer typically makes a Mollie with the width tapering abruptly to the lever.
The originals were actually much more graceful. I'm not sure what generated that practice of guys making the outer taper look like a fade one might expect on a pyramid bow handle.
It's almost like someone sketched a rough outline as a starting point before refining and most people just leave that outline.