the mass principle in one sentence

[Badger]

SCp, with a lot of mathematics you could apply the mass to the demensions of the bow relatively close before starting but it is not neccessary and would never be as accurate as just zeroing in as you build the bow, forget about the thickness of a bow, ignore it! That happens when you tiller. All you are doing with the mass pricilpe is adjusting the width on a pre-determined design, nothing more. If the mass is way off then you adjust the design but only if neccessary. I hope I can get you to try this. It is actually very simple once understould. Steve

[scp]

The mass principle says that it always takes the same amount of wood mass to do the same amount of work in a bow. But, of course, how can it be otherwise? Still, is this principle falsifiable?

[George Tsoukalas]

"Jawge, a principle must be much more than a technique. I BELIVE in the underlying intuition. But unless you formulate the principle to make it falsifiable, you are not there yet."

Please explain what you mean. I detect an underlying assumption here on your part but I don't want to elaborate until your philosophy on bow making is clear to me.  Suffice to say, that in my view, building bows is NOT an exercise in the scientific method. So you have a log stave in front of you what do you do to turn it into a bow?

Also, I just built a 51# rigid handle osage bow, drawn 26 in that happens to fall at 18 oz in mass. I did not set out to achieve that mass figure. It just happened. I checked the mass to tell Badger. No other reason.

"Don't get me wrong. I'm not saying you are wrong. I'm saying good bowyers need to make their assumptions more explicit. Knowledge mining is never easy and can be quite irritating sometimes.
The mass principle in a paragraph, anyone?"

I gave you the mass principle in one sentence and then explained it in a post approved by the author of the mass principle itself (Badger). LOL.

"The mass principle is a technique that allows the bowyer to manipulate the mass of the bow in order to maximize performance."

Now either you don't understand (I can't see your non verbal cues like I did when I was teaching so I can't tell) or you don't think the mass principle is a viable technique. It is a technique. Is the name a problem? This is not science, scp. This is art. Jawge

[Justin Snyder]

But it probably cannot tell us whether we need to lighten the unbending tips instead of scraping the side of the working part of the limbs. Can it? Better yet, can we refine the principle to do so?

scp, the formula isn't supposed to tell you to use stiff tips or rigid risers. It tells us if we have done them properly. If you have more wood on the unbending tips than is needed to keep them unbending, it will tell you that you are over weight.  Steve mentions that he doesn't advocate lighter bows, and it is true. Some of us make bows too light/narrow, and the formula helps to prevent these occasions also. I have previously thought that some species, because of their superior qualities could cheat the formula and have less weight. Steve helped me with the formula on one such bow. I came in about 1 ounce lighter than Steve projected. I thought it was close enough since this was only about 5% of total weight. The bow held up for 4 months then started showing signs of damage. Steve is as humble as he is helpfull so I will say it. This mass principle is extraordinary. It is probably the best scientific tool available to let a bowyer know if he is getting the most from a bow design.
One paragraph.....
All woods are not of even density. All trees of one species are not of one density. Badgers bow mass principle helps us to refine design to fit the particular piece of wood, not the general species or type of wood. The formula uses design characteristics such as but not limited to, length, riser style, amount of reflex/deflex compared with draw length and draw weight to help us to eliminate excess wood that would decrease performance. It also uses those same principles to help us not make bows that will not stand up to the strain that we are putting upon the wood by building to light, too narrow, or too short of a bow by telling us when we are asking too much of the wood.
One last thing. The principle is more accurate than the interpretation by the human. If there is an error, it is in the human inturpretation.

[George Tsoukalas]

scp, no, it is not and that's why it can be called a principle. The underlying principle is the concept of density (d=m/v). Osage (at 0.8 g/cc ) is going to have the same mass in a smaller volume when compared to hickory at 0.7 g/cc. Practically speaking, without even considering the mass principle,  the reason why the bowyer should begin to narrow the limbs is that too thin limbs can break easier.  So when I see a limb unresponsive to belly removal I slowly begin to narrow the limbs. Keep the questions coming. jawge

[scp]

Justin Snyder, you are talking about the PRIMARY mass principle. "According to the mass principle, given a particular specification of a bow, its optimal total mass is reasonably predictable and attainable." Nobody seems to have any problem with that.

But Badger goes much further than that. He thinks the principle is useful in predictng or prescribing the proper mass distribution in a well made bow. When I ask him how, he just invokes the sound bow design principles. I'm sure mass is relevant in there somewhere somehow. But where, when, and how?

[scp]

scp, no, it is not and that's why it can be called a principle. The underlying principle is the concept of density (d=m/v).

"A hypothesis, proposition, or theory is 'scientific' only if it is falsifiable."
http://en.wikipedia.org/wiki/Falsifiability

Are you trying to say that the mass principle is a semantic one?

[Badger]

     Maybe priinciple is the wrong word, I will call Jim Hamm and hav him recall all the books immediately so we can change that word and reprint all the books. I believ it is falsifiable, build a bow 20% under the recomended mass and see how it performs, or build it 20% over the recomended mass and see how it performs. The whole idea here is wether or not it works! It seems to work for me and several others, why are you so stuck on definitions. No claim was ever made that it was exact science, it is just another tool used to attain proper demensions, I am not going to spend anymore time defining a word. Try it, if you ike it use it, if you don't like it, don't use it. Steve

[adb]

scp- wow. You must have been on your High School debatig team. 

[half eye]

science, science, science......maybe you ought to read the headline banner, something about "primitive archer". I think I'll see if I can book some time with some stupid oldworld bow-maker. You know, the one that does it by feel and devotion to the craft and probably aint got a pencil, ruler, bandsaw and for sure no desire beyond making a good solid bow. He probably dont even know what a chronograph is let alone what it's used for. I mean hell who wants to settle for something that kills food, shoots where you look, etc. etc.

I hope you get all the stupid people like me good and confussed, because God forbid somebody wants to take up the hobby for fun. Why dont you just get with Socrates and debate how many fairy's can dance on the head of a pin? I hold 2 United States Patents in the field of anti-ballistic armor, a published author blah, blah, blah (and so what?). For the life of me I dont see why this is even an issue. I thought there were bows around for at least 10,000 years and never realized that all them bows were crap up untill the "Bibles" got published.

There are a few of us stupid, crappy bow builders that sort of enjoy the exploration of the process, and the mystery of it.
half eye

[Badger]

       Halfeye, I agree with you 100% on a personnal level. Bow making is kind of a lost art that we have been rediscovering. Looking back at some of the old designs it it obvious these guys knew exactly what they were doing and very good at doing it. We don't do it here for survival we do it as a hobby. They may have spent a lifetime or a particular civilization or village may have spent generations developing and improving one style of bow. As hobby bow builders many of us would like to experiement with a lot of different designs from a lot of different woods. Little clues and the logic that goes into designing a bow is helpful, without the combined input from the hundreds of bowers we have today it wouldn't be likely we could take it as far as we have in our own lifetime. I have settled into favorite designs of just basic stave bows, straight and basic. But the journey has been fun never the less. Steve

[Marc St Louis]

Steve, I am trying to remember if you discuss heat-treating, and how it jives with the mass principle.  If a finished bow is heat treated, it will often pick up several pounds.  Does that mean the mass principle needs a fudge factor? How do you deal with this?

I'm very impressed with your willingness to keep answering everybody's questions; you're obviously a man of character.

Can I take a stab at the one sentence thing?   "All (usable bow) woods are equal when expressed as elasticity per unit of mass."

Wood is comprised of a significant amount of air trapped inside the cells.  Dry heat forces some of this air out especially on the belly's surface wood.  This would make the wood more dense and generally speaking the denser the wood the higher the compression strength.

[Marc St Louis]

science, science, science......maybe you ought to read the headline banner, something about "primitive archer". I think I'll see if I can book some time with some stupid oldworld bow-maker. You know, the one that does it by feel and devotion to the craft and probably aint got a pencil, ruler, bandsaw and for sure no desire beyond making a good solid bow. He probably dont even know what a chronograph is let alone what it's used for. I mean hell who wants to settle for something that kills food, shoots where you look, etc. etc.

I hope you get all the stupid people like me good and confussed, because God forbid somebody wants to take up the hobby for fun. Why dont you just get with Socrates and debate how many fairy's can dance on the head of a pin? I hold 2 United States Patents in the field of anti-ballistic armor, a published author blah, blah, blah (and so what?). For the life of me I dont see why this is even an issue. I thought there were bows around for at least 10,000 years and never realized that all them bows were crap up untill the "Bibles" got published.

There are a few of us stupid, crappy bow builders that sort of enjoy the exploration of the process, and the mystery of it.
half eye

half eye

Aren't you the guy that posted something about making a bow from a picture using some kind of a formula?

[scp]

I believ it is falsifiable, build a bow 20% under the recomended mass and see how it performs, or build it 20% over the recomended mass and see how it performs.

Me too. The PRIMARY mass principle is falsifiable. Or at least, it appears that we can make it so.
The mass principle says that it always takes the same amount of wood mass to do the same amount of work in a bow.

If we wanna go further and talk about the mass principle concerning the proper distribution of mass in a well made bow, we probably have to talk about the relationship between the mass, the width, and the thickness of each sctions of the bow. You have been making several interesting statements about it. I don't think you are wrong. But I do believe that many of the underlying assumptions or qualifications have to be made explicit. I repeat:

Your said "you ignore thickness when distributing mass." What do you mean by "when distributing mass"? It cannot mean "when we are tillering," can it? How can we ignore thickness when we are tillering? Does it mean "when we are applying the mass principle after most of the tillering is done"?

You also said, "The distribution of the mass is determined by width only." Then I have to ask when? When we are designing a bow? You might be thinking about when the bow is almost finished and you are trying to apply the mass principle to that bow. Why can't we determine the proper distribution of mass by thickness when we are designing a new bow?

[Badger]

   SCP, when using this formula width and mass are almost interchangeble. I don't even consider thickness here in anyway because it is not negotiable, I do know a gentleman who can prefigure a bow's thickess and width and mass but is is very difficult, innaccurate and not really useable for most of us.
The distribution of the mass and the tiller shape are predetermined by the bowyer at the design stage before the bow is started.
All the formula does is to direct the bowyer in the final stages to fine tuning the width. Steve