Edge grained Maple backed Yew

[DC]

I did a little messing around with a piece of bamboo for a test bow. I had noticed that the "lever" of a bows limb gets shorter as it bends because the length of a lever is measured in a straight line from point of effort to the fulcrum. So I bent the bamboo to "brace" height and measured the lever length. Then I bent it to full draw and did the same. As you can imagine the lever got shorter. Then I bent the "limb" into reflex and deflexed it at the handle. When I bent the limb the first part
 of the stroke was straightening it so the lever got longer and then it started getting shorter but the net result was that the lever wasn't as short at full draw. I think the deflexed handle helps because it delays or reduces the bend at full draw. This gives more leverage at full draw. When I start thinking about how this affects energy storage my brain kind of rebels on me. The lever length only changes by a few percent but it's a good few percent. Lots of people probably know this but I thought it was interesting.

[Badger]

  Good observation. Every part of a limb is responding to it's own relative string angle. The more of a limb you have at a low angle the better leverage your arrow has to suck out energy.

[sleek]

I did a little messing around with a piece of bamboo for a test bow. I had noticed that the "lever" of a bows limb gets shorter as it bends because the length of a lever is measured in a straight line from point of effort to the fulcrum. So I bent the bamboo to "brace" height and measured the lever length. Then I bent it to full draw and did the same. As you can imagine the lever got shorter. Then I bent the "limb" into reflex and deflexed it at the handle. When I bent the limb the first part
 of the stroke was straightening it so the lever got longer and then it started getting shorter but the net result was that the lever wasn't as short at full draw. I think the deflexed handle helps because it delays or reduces the bend at full draw. This gives more leverage at full draw. When I start thinking about how this affects energy storage my brain kind of rebels on me. The lever length only changes by a few percent but it's a good few percent. Lots of people probably know this but I thought it was interesting.

That works well when its bent without a string. With a string, it cant get longer, that means that because it wants too, its forced to bend further than it otherwise would per inch of draw, storing more energy in that draw inch than otherwise would have been. Its really a damn good design feature,  and one I have used in my last two short bows. I am trying to figure how to make the most of that.

[DC]

I did a little messing around with a piece of bamboo for a test bow. I had noticed that the "lever" of a bows limb gets shorter as it bends because the length of a lever is measured in a straight line from point of effort to the fulcrum. So I bent the bamboo to "brace" height and measured the lever length. Then I bent it to full draw and did the same. As you can imagine the lever got shorter. Then I bent the "limb" into reflex and deflexed it at the handle. When I bent the limb the first part
 of the stroke was straightening it so the lever got longer and then it started getting shorter but the net result was that the lever wasn't as short at full draw. I think the deflexed handle helps because it delays or reduces the bend at full draw. This gives more leverage at full draw. When I start thinking about how this affects energy storage my brain kind of rebels on me. The lever length only changes by a few percent but it's a good few percent. Lots of people probably know this but I thought it was interesting.

That works well when its bent without a string. With a string, it cant get longer, that means that because it wants too, its forced to bend further than it otherwise would per inch of draw, storing more energy in that draw inch than otherwise would have been. Its really a damn good design feature,  and one I have used in my last two short bows. I am trying to figure how to make the most of that.

I had a string on it. I marked where the tip was on a background paper at brace height. Then I pulled it back an inch and marked the tip again etc. etc. out to 28". Joined all the dots and the arc from the deflexed limb stayed outside the regular limb. It did get longer. I'll have to do it again, it was a while ago and it's getting kind of faint. . When I put a recurved tip on it the effect was even more dramatic, although I did use rather big hooks. The string lengthening characteristic of recurves adds to the limb lengthening of the reflex so the net gain is more.

[simk]

DC, you are doing a great job, one after another, respect! I just destroyed my latest deflex/reflex-project by stringing it the wrong way - beginners life is hard sometimes but seing others work helps to motivate again! thanx

[Bojahu]

Love the angular look to it! very nice! I think that is the style I will be attempting next.

[Morgan]

I look forward to all your posts. Well done!

[sleek]

I did a little messing around with a piece of bamboo for a test bow. I had noticed that the "lever" of a bows limb gets shorter as it bends because the length of a lever is measured in a straight line from point of effort to the fulcrum. So I bent the bamboo to "brace" height and measured the lever length. Then I bent it to full draw and did the same. As you can imagine the lever got shorter. Then I bent the "limb" into reflex and deflexed it at the handle. When I bent the limb the first part
 of the stroke was straightening it so the lever got longer and then it started getting shorter but the net result was that the lever wasn't as short at full draw. I think the deflexed handle helps because it delays or reduces the bend at full draw. This gives more leverage at full draw. When I start thinking about how this affects energy storage my brain kind of rebels on me. The lever length only changes by a few percent but it's a good few percent. Lots of people probably know this but I thought it was interesting.

That works well when its bent without a string. With a string, it cant get longer, that means that because it wants too, its forced to bend further than it otherwise would per inch of draw, storing more energy in that draw inch than otherwise would have been. Its really a damn good design feature,  and one I have used in my last two short bows. I am trying to figure how to make the most of that.

I had a string on it. I marked where the tip was on a background paper at brace height. Then I pulled it back an inch and marked the tip again etc. etc. out to 28". Joined all the dots and the arc from the deflexed limb stayed outside the regular limb. It did get longer. I'll have to do it again, it was a while ago and it's getting kind of faint. . When I put a recurved tip on it the effect was even more dramatic, although I did use rather big hooks. The string lengthening characteristic of recurves adds to the limb lengthening of the reflex so the net gain is more.

Id like to do this with markers tied to the tips. It took some thought for me before the obvious hit me. When the string makes contact with the belly on a recurve, the bow can get longer as its drawn. If not, then it can only get shorter.

Sometimes,  the amount of thought I need to put into a simple concept makes me question my own genius. But then, only a fool wouldnt question himself so, I must be good to go

[DC]

The reflexed bow with a deflexed handle does get shorter but not as much. A straight bows limbs are bent at brace. Our RD bows limbs are straight(or just about) at brace. Like an Egyptian bow.

[dolgima]

I did a little messing around with a piece of bamboo for a test bow. I had noticed that the "lever" of a bows limb gets shorter as it bends because the length of a lever is measured in a straight line from point of effort to the fulcrum. So I bent the bamboo to "brace" height and measured the lever length. Then I bent it to full draw and did the same. As you can imagine the lever got shorter. Then I bent the "limb" into reflex and deflexed it at the handle. When I bent the limb the first part
 of the stroke was straightening it so the lever got longer and then it started getting shorter but the net result was that the lever wasn't as short at full draw. I think the deflexed handle helps because it delays or reduces the bend at full draw. This gives more leverage at full draw. When I start thinking about how this affects energy storage my brain kind of rebels on me. The lever length only changes by a few percent but it's a good few percent. Lots of people probably know this but I thought it was interesting.

DC I really like your bow design and impressed by arrow speed. I think it's faster than fiberglass laminated bow. I want to fully understand what you said and others comments about this bow design but i'm not anglophone so it's little bit difficult to understand. If it's possible could you explain intelligibly or with some pictures ?

I think your bow design is close to modern olympic  recurve bow  is this design better than typical horn bow design ?

and how to make wood laminated bow with your design?

1. for deflex on handle  I think gluing two billets with deflex is the only way. is that right?  beacuase handle is thick so It's hard to put deflex with dry heat or steam

2. how to put reflex on limbs ?  bending with heat or just put on reflex zig after laminate with backing material ?

3. to me it seems there is recurve on tip with large curvature (small radius)   how to bend like that? tip thickness is thin? or  using kerf cut for bending?

4. edge grain is different with quarter sawn or rift sawn wood?

sorry for my atrocious english ~

[PatM]

You can readily deflex a handle with steam by thinning the material and then building it back up after bending.

[DC]

To tell the truth I printed a few pictures from this thread http://www.primitivearcher.com/smf/index.php/topic,62271.0.html

and taped them on my tillering board. Made a bow that looked the same as the pictures and it worked. I've never worked with horn so I can't say. I've also never made a laminated bow, just self and backed bows.

1. Like PatM says there is more than one way to deflex the handle. Choose the one that works for your skills and tools.
2. This bow had some reflex already but you can glue it all in or prebend with steam. I always glue some in just because I read that Perry reflex is good and it has worked. You can heat treat the belly before glueup if you want.
3. Any or all that you mentioned. Yew is fairly easy to bend. I use this method now. I found that I can get really tight bends with this jig http://www.primitivearcher.com/smf/index.php/topic,62668.msg878994.html#msg878994
4. Edge grain is quarter sawn, same thing. It maybe a local term.

Your English is probably less atrocious than my explanations. Let me know if you need more.

[dolgima]

thanks for kind and explicit reply.
I have some more questions.

1. I read about Perry reflex  several times but I still don't understand..   Perry reflex means gluing backing and belly material  without prebending ? If it is, it's just normal way to put reflex for backed bow. isn't it ?   and what's the advantage of it ?

2. The reason why I mention about horn bow was because of it's design not material.  when I see for example korean horn bow profile, when it's unbraced it has only reflex and recurve and when it's braced 5 curves(reflex on handle)   If we compare  this horn bow design with your angular Egyptian style bow  what's the difference ?

3. For wood based backed or self bow, this Egyptian style bow is ideal design  when it comes to energy efficiency, arrow speed  something like that ?

4. If you used bamboo as backing material, arrow speed would be faster ?

5. if you shoot with your hand not on shooting machine, it could be little bit slower ? or not much difference ?

6. role of deflex handle ?

7. http://www.primitivearcher.com/smf/index.php/topic,62668.msg878994.html#msg878994 if I bend recurve like this, it won't tear? why put strip? because wood take less tension thanks to metal strip?  If it is, I must clamp  and vise  tightly so strip can do his role ?


even myself, i can't  understand what i'm talking about...  sorry again and thanks in advance

[DC]

thanks for kind and explicit reply.
I have some more questions.

1. I read about Perry reflex  several times but I still don't understand..   Perry reflex means gluing backing and belly material  without prebending ? If it is, it's just normal way to put reflex for backed bow. isn't it ?   and what's the advantage of it ?

2. The reason why I mention about horn bow was because of it's design not material.  when I see for example korean horn bow profile, when it's unbraced it has only reflex and recurve and when it's braced 5 curves(reflex on handle)   If we compare  this horn bow design with your angular Egyptian style bow  what's the difference ?

3. For wood based backed or self bow, this Egyptian style bow is ideal design  when it comes to energy efficiency, arrow speed  something like that ?

4. If you used bamboo as backing material, arrow speed would be faster ?

5. if you shoot with your hand not on shooting machine, it could be little bit slower ? or not much difference ?

6. role of deflex handle ?


even myself, i can't  understand what i'm talking about...  sorry again and thanks in advance

Now you've gotten deep into stuff that I'm not sure of. I believe Perry Reflex more or less the same as gluing reflex has always been done. Dan Perry explained why it works and so his name got attached. There will be some disagreement about this but that's just my take on it. Whatever you call it, it seems to work.
My bow is 64" long, horn bows are usually shorter so that the horn and sinew are worked harder. I'm not really sure but I think the difference is just the use of different material  to take more strain. I saw a show about Egypt the other night and apparently Egyptian bows were horn and sinew. I'm not really good with different designs, you'll have to ask someone else.
I've made bamboo backed yew and they are also fast. The maple surprised me but I'd hate to bet on the difference. I'm pretty sure it would be slower, I have a very crummy, inconsistent release. I'm not a good shot.
Role of a deflex handle?? Don't know for sure. I think it uses some of the energy that is normally wasted in bracing but really, I don't know.

Sorry you didn't get better answers.

[Badger]

     The two most important things I think a de flexed handle does is allow the bow to hit full draw with less strain on the wood. The wood is in better shape and take less set thus less hysteresis. The other thing I see is that every part of the limb is responding to its respective angle to the string during all parts of the draw and release.  A deflexed limb maintains lower string angles for better energy storage. It also tend to wind back up more cleanly after the shot from the inner limb out getting less vibration and power loss.

   Every shooter is different, from 10 fps slower to 10 fps faster in not unusual. The great majority of shooters will shoot about 7 fps slower than the machine.

   Perry reflex does help to increase performance, lots of speculation as to why but it does help.

  I don't think Bamboo is any faster than other good backings, it is tough and reliable so i like it.

 No comment on the Egyptian bows