Update on Mass Theory

[Badger]

     I thought I would post a little update now and then for those who follow or use the mass principle. Yew wood does consistently come in below projected mass. I figure 10% less for backed bows and this is where yew seems to come in with self bows. So far this has helf true with both yew flatbows and elb style bows. Mass is based on less than 1" set and sufficiently dry wood for the species. Any feed back is always appreciated as it is still eveolving. Steve

[Marc St Louis]

Steve
I just finished a Yew recurve and I haven't weighed the bow yet but it seems very light in the hand for the draw weight

[Badger]

  Mark, are you going to post the bow? I would really like to see one of your recurves in yew. I just finished a flat bow that I am really happy with, did a recurve a couple of months ago but didn't reflex it at all, I guess I underestimated the wood. Steve

[jkekoni]

I am just wondering that the following woods works as underweight:
Yew,Ipe, Junipers(=erc).

The following woods are stronger in compression than tenssion:
Yew, Ipe, Junipers

I do not think this is a coninsidense. I think that typical design with a typical wood is that the back is overbuild compared to the belly.
This makes the bow heavier and put too much strain on the belly, reulting more set and therefore worse cast

Could this mean that the typical flat limb gemetry is just inefficient for those woods and
narrowed back would correct some(all?) or the deficiency?

(Now I am arguing for the mass thery... for a change.)

[Badger]

   Jkoni, I am pretty sure your logic is pretty sound on the yew and the juniper, I seldom use ipe as a selfbow so normaly use it as I do most other woods, Sinew backed bows can come in lighter for the same reason. Steve

[David Long]

Steve, to give us a better feel for how significant you think the 10% figure is, can you tell us how much variation you get within a given wood? For example, if you made a bunch of maple bows (design can vary or stay the same) do they all miss the projected mark by a lot less than 10%? Dave