Arvins 62" osage design

[willie]

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

   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.

[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]

a wide pyramid profile bow that uses levers at the tips

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.

I feel more shock in the reflex thru out the length of the bow.

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.

[sleek]

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

   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.

Mass itself has very little to do with a bow in my opinion. Of course where mass is located is important, but mass is a function of, not a design feature of a bow.

Mass is only a biproduct of the bows width and thickness. Its width determines the stress it can take and its thickness determines how much it can bend before taking set. The combination of those two individual design parameters are what gives a bow its mass. Applied incorrectly, you can get a bow the correct mass bit not the correct draw weight the mass is supposed to give. The entire idea of chasing mass is not going to get anyone anywhere.

The stress of compression is spread out iver surface area, the stress of tension likewise. You need the correct surface area for the draw weight of the bow, and the correct thickness for the bend radius. The stresses are not distributed across the mass.

So the question is, how wide and long does a bow need to be to not take set. The formula I have been working on is an attempt to solve that issue.Im about 80% certain i have it figured out, but without more bows of many different wood species built, i wont be 100%.  Its a simple formula The specific gravity is used along with the draw weight and from there you get how many sq inches of working limb you need. Soon as I know i am not putting out bad info, ill make a phone app that lets you put in your desired bow stats and it will tell you what you need to build.

[Selfbowman]

How long should a bow be 1” wide for half limb  the limb then a even taper from there. Just curious Kevin .

[sleek]

Ill run that when I get off work. What poundage do you want?

[Selfbowman]

Fifty pound and my normal reflex in the end.  8”!stiff handle

[willie]

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.

you have a build of your osage 67" pyramid design in glass?

I think it would be quite informative to see a pic of that glass bow at full draw on the tiller tree.

[Selfbowman]

It had so much shock I gave it away!🤠🤠🤠

[willie]

It had so much shock I gave it away!🤠🤠🤠

lol, I had a shakespeare 66" that left it's home on the bow rack the same way.

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 .

maybe a direct comparison could be hard. but the underlying reasons should be similar.  too much flexibility in the outers where the limb return speed is higher and thus has more momentum when the string stops the limb?

can you comment on the deflexed recurved you recently built? is it damper in the hand or more so that your straight backed 67/68 inchers?  I assume you have had a chance to shoot some light arrows from it recently.

[sleek]

Fifty pound and my normal reflex in the end.  8”!stiff handle

Assuming no stiff tips, the entire bow bends, You taper to .25 nocks.

The bow limbs will be parallel, one inch wide for 25.875 inches

Then you start the taper from one inch wide to .25 for 13.79"

Thats 39.665 inches long limb, double that and add your 8 inch handle you get a long bow of 87.33 inches total.

I imagine that bow would throw a heavy arrow very well and be well suited for a very long draw, which would allow for higher than typical speeds. How fast is a pure guess based on what the end draw length would be.

Now I wonder what virtual bow says about your hypothetical bow Arvin? Im curios to check my work against that. It would be fun to have a bow build off competition between my formula and the virtual bows design. 

[Selfbowman]

Kevin there was some mention of extremely long bows in bowyers bible 1 I think . I might go back and review that section. Kevin Ive got BJ fixing to build some narrow flight bows . If it can be done with no set at 25” by him it might Poke a hole in your theory. That we will have to watch.  Brian can tiller a bow.

[sleek]

Kevin there was some mention of extremely long bows in bowyers bible 1 I think . I might go back and review that section. Kevin Ive got BJ fixing to build some narrow flight bows . If it can be done with no set at 25” by him it might Poke a hole in your theory. That we will have to watch.  Brian can tiller a bow.

Im often excited to be shown im wrong. It gives me an opportunity to learn more and more quickly.

Which theory are you refering too? Im full of them lol.