Different woods different styles

[Marc St Louis]

      I just had one of those AHA!! moments. It has been driving me up a wall that these extra wide bows are comming in at significantly less than my own mass formula suggests. We always think of width as mass when we talk wood bows. I did a little bit of math a few minutes ago, as much as a high school drop out can do that is. It does appear that mathematicaly it works out that at a certain point extra width can and often does become more economical with mass.

      Maybe some of you math geeks can help me out on this.  oz.

  wide bow 58" long, 50#@26", 10" handle and fades, static recurves 4" behind handle, 13" total working limb, limbs mostly parallel with slight but progressive taper. Mass weight 18.5 oz.  Limb cross section .340X 1.562=.531sq unches
                                             Narrow bow, 19.5 oz          "      .420X  1.375=.577 sq inches

 Smaller overall area in the cross section of the wider bow. Mainly because of slight almost invisible wood damage.

Steve
It shouldn't work that way.  If wood is 8 times stronger in thickness and only 2 times in width then logically to get a same draw weight you would have more mass with the wider bow.  I'm sure there are other factors that come into play though, the one that comes to mind is that wider limbs will more likely keep their spring (less crushed cells) better than narrow limbs which would therefore boost their ability to store energy.  Sheesh, this is just too complex.

[toomanyknots]

Now mention of the tillering tree makes me want to put my 2 cents in.  I know they are safe but if you want to get the most out of your bow then pull it by hand during the tillering process.  Feeling what your bow does as it's being drawn back is important.  Also keeping the bow at full draw on the tree, or by hand, or with a T stick for more than 5 seconds is a waste especially when you have finished tillering your bow.  You don't shoot that way so why subject the bow to this?

I second this to oblivion and back. I use a mirror to tiller all my bows. It is long enough I can step on the string and draw the bow horizontally. The only time they ever sit on a static wooden tiller tree (or anything like one) is when I make a bow too long or heavy for me to string, and I need to pull it on the longstring to string it, so I will pull the longstring and slip the string on one of the tiller tree notches in order to string it. Doing it this way, I will never string a bow with a hinge, because it is so apparent. And I will not string a bow with unbalanced limbs most of the time, for the same reason. For the most part I will not string a bow that does not have an already good tiller, but some may argue I longstring tiller too far.

[artcher1]

Not much I can add to this discussion, but I would like to see some kind of standard where by we can judge each others bow's performance. For example, once I get my bow to length and weight, I simply weight the first 3". If the bow is braced at 5 1/2" I draw it down to 8 1/2" and record it's weight. I'm looking for at least 12# or over at this point. I know from experience that it'll drop 1# once the honeymoon effect is over. Several variables of course, like reflexed/recurved bows, but at least it's a method of determining what I've got.

Anybody want to share their numbers........Art

[Badger]

  I use the same methods myself. I have the bow 90% tillered before I ever bend it more than a few inches. But for the sake of expalining it I use the tiller tree and a scale.

    As for the width making it lighter. It can only happen if the narrower bow is killing off some wood cells. If your wood is pristine narrower is always lower mass. If a bow needs to be a bit wider to keep the wood in pristine condition it also becomes more efficient with the use of the wood.

    Typicaly I usually either heat shape or glue up bows with from 3 1/2 to 4" reflex. I often finish after shooting in with 1 1/2" reflex and I am fine with that. If I can take that same bow and maintain all but maybe 1" of the reflex I put in it will perform much better even if I have to go a bit wider to do that. If I go wide enough to avoid any set I have all my wood cells working instead of sleeping and it takes less.

[Badger]

  Thats exactly right Art, I figure about 2# loss for honeymoon and about 1/2" of set.

[Danzn Bar]

Wow I'm really surprise with myself,  I'm beginning to understand all of this.  The light came on for me about 3 bows ago.  And this conversation is fine tuning my thoughts.  this is great keep it going.  you guys have got to have more great stuff in your heads.
Thanks,
DBar

[artcher1]

I'm only drawing 24-25" on my best days Steve. So that would explain that 1# difference in the honeymoon effect.......Art

[Badger]

 Dan, we used to have conversations like this all the time. The bows kept getting better and better because folks became more aware of proper demensions. There is less room for improvement now that there was 10 years ago. Very little need to really know anything more than what you can pick up at these web sites. For some of you who are interested in going to other levels I am kind of presenting this as potentially a new frontier worthy of looking at. I guess you would call it recognizing, identifying and countering losses of power.

[Badger]

Art, good point, I have most of my losses starting about 23", I seldom tiller past 28".

[echatham]

Chapter?  where can i read it?  Mass principal?  seen the term alot, but where i can i read up on it?  man there are some great conversations and great thinkers over here on PA.  lovin it.

[Eric Garza]

...I have most of my losses starting about 23", I seldom tiller past 28".

Badger, when you note that you have most of your losses starting at about 23 inches, what is the total length of these bows? This is me hearkening back to a post I started a month or two back pondering relationships between performance and the ratio between the draw length and total length of a bow...

[Badger]

 Eric, the losses can be relatively minor but shorter bows more so than longer bows but to some extent all bows that I think I have designed to draw 28".

[soy]

this is a good read so far for the poses the question is the hope of a new book on the back burner???

[vinemaplebows]

Damnit Steve, Thought you said we were not saying anything for another couple yrs.......now here comes more bow pics!!

[WhitefeatherFout]

Very interesting discussion.  This is pretty cool timing as I have been shooting a bow similar to what you are describing and although I haven't done any real "testing" with it, it would seem there are some noticeable advantages to it over a skinnier design.  The bow was made by Brad Smith and he sent it to me to shoot for a few weeks.  It is an Osage bendy handle 61ntn.  It is about 1 3/4" wide until the last 11-12".  I would say it averages about 3/8" thick.  It has some character and Brad done a great job tillering it.  I think this bow was around 67@28.  This was the first time I shot a bow of this design.  I was skeptical but was surprised at how well it performed.  I think the wider limbs also helped with the character parts and help reduce any set or string follow.  This bow was kind of an eye opener for me as far as the wider style goes and this discussion is confirming this wasn't a fluke.  I suppose I'm going to have to rethink the whole wide limb deal.  Thanks for bringing this up Steve.  Matt