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Arvins 62" osage design

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willie:
this quote from Badger is from another thread, but I have found his observations  about wider limbs
interesting


--- Quote from: Badger on April 14, 2020, 12:42:02 pm ---   I did some tests a few years ago on exceptionally wide osage bows. The results kind of disagreed with my own mass theory.  I built several osage flat bows with stiff handles at about 2" wide to 2 1/4 inches wide. To my surprise the mass came in slightly lower than the 1  1/2" bows. I use to build all my 50# osage bows at about 1 1/8 wide to about 1 1/4 wide. I found I got less set when going wider and I also was adding mass but they were still better performers because of less set. When I bumped them up even wider I fully expected to see a substantial increase in mass but it didn't happen. The bows came out much thinner than I would have expected also. The only way this is possible is if at 1 1/2" wide I was still doing more damage to the wood than I thought I was.

--- End quote ---

mmattockx:
I can't claim to have done all the work that Badger has (I don't know if anyone can), but his claim that set is exceedingly damaging to performance does seem to make sense to me. That implies avoiding set is more important than extracting the last 1% out of the wood.

Based on all the modelling I have done, a wide pyramid profile bow that uses levers at the tips will offer the best performance from the wood along with being the most forgiving in terms of extra weight not hurting performance as much as other designs. It strains all the wood equally, keeps the moving mass as low as possible and if you overbuild it by a few % the extra mass is mostly near the grip and doesn't hurt performance as much. Reflex may be worthwhile, because it increases early draw weight and that is good for performance as well, but you would need to look at the differences between reflexing the whole limb versus recurved tips.


Mark

Selfbowman:
Ok let’s talk shock! Shock kills speed in my opinion. Please chine  in here if you’ve built plenty bows with reflex thru out the length of the bow vs putting the be reflex in the last 10-12”. I feel more shock in the reflex thru out the length of the bow. It’s interesting what you observed in your computer designs Mark. Kevin and I feel there is a whip like action in the bow limbs come forward. With the reflex in the last 10-12” may effect how the whip action takes place . Just my brain thinking.🤠🤠🤠

mmattockx:

--- Quote from: mmattockx on December 17, 2024, 09:59:33 pm ---a wide pyramid profile bow that uses levers at the tips
--- End quote ---

I hate quoting myself, but I realized this may be ambiguous. The pyramid profile I am talking about is not a straight taper from fades to the nock, the sides of the bow are convex and curved outwards a bit from straight. The levers happen because the ideal pyramid profile tapers to a sharp point at the nocks, but this is physically impossible because we need material for the nocks. So the profile shape is drawn to a sharp point at the nock, then a width for the nock is chosen and that width carries in towards the grip until it crosses the profile shape. If that is unclear I can make a sketch to illustrate better.



--- Quote from: Selfbowman on December 18, 2024, 12:12:29 pm ---I feel more shock in the reflex thru out the length of the bow.
--- End quote ---

That's an interesting observation, Arvin. If you look at fibreglass recurves the limb bend tends to have the nocks move more vertically than horizontally. This seems to reduce shock and vibration. Some of the FG bowyers think this is because the limb mass is moving vertically, so the forces tend to cancel out between the top and bottom limb and it helps stop the limbs more quickly.

I have no idea if their theory is correct or not, but when you only reflex the tips it does the same thing to the limb bend and tip path as the FG recurves, just to a lesser extent.


Mark

Selfbowman:
Is this why Howard Hill bows are shocky. Some had a slight reflex thru out the bow. The smoothest shooting glass longbows i e shot  had some deflex in the handle fade section and slightly recurved . That design holds the fight records also. I think it’s hard to compare wood to fiberglass in design though . This pyramid design in wood is more compatible than glass . I did this design in a glass bow and it was full of shock. Don’t ask me why. I don’t know.

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