Selfbow - Dynamic (vs. static) recurves

[PatM]

That is still a substantial amount of possible movement. 

[PEARL DRUMS]

    I think when you ask the question can recurves work or not the simple answer would be that the wood in a recurve can't bend anymore or less that the wood in any other part of the bow relative to its thickness. If it does exceed a certain bend it will take set which would mean all or part of the recurve gets pulled out.

That's how I see it, Steve. I also firmly believe a person cant claim anything works just fine until a bow has no less than a 1500 shots through it. What works and look great for full draw pics doesn't always translate down the road of shooting. I've learned that lesson plenty of times now in many different areas of building bows. Right about the time I thought I had out-smarted something, longevity sneaks in and hits you in the face with reality.

[Pat B]

I've seen static recurves with spined kerfs but not working recurves. 

[gfugal]

    I think when you ask the question can recurves work or not the simple answer would be that the wood in a recurve can't bend anymore or less that the wood in any other part of the bow relative to its thickness. If it does exceed a certain bend it will take set which would mean all or part of the recurve gets pulled out.

+1
To me, It depends on how much work you classify as working recurve. I don't view a working recurve as pulling the recurve flat when you draw it, but rather just ever so slightly unwinding. I also think radius applies a lot. I mean we've all seen working Reflex/Deflex bows were it pulls out straight but effectively curls back when it returns to brace, but that's a much larger recurve radius (so much that it just gets called reflex). I don't think you're going to get much work out of a 2-inch radius recurve without breaking it or getting it to permanently lose some of its bend.

[gfugal]

I also think limb material, and how the recurve was achieved plays a role. Better material like Osage can handle a greater un-bending recurve without getting set per se, this is also why I think it's possible to get completely unwinding recurve out of Cough(fiberglass). But it might not all be set. It's more likely that you're loosing that recurve due to losing the bend you put into it. Some methods may prove more "lasting" than others. Which methods those are I couldn't say. I would think something like boiling or steam would hold better than dry heat but I have nothing to back that up. I also think that the thinner the limb is before you recurve, it will help it stay put. Maybe longer steamings/boilings or even repeated steaming/boiling will allow it to hold better. Who knows? Someone should do a study and experiment with that. I think it's safe to say that Perry reflex holds better than steam, boiling, or dry heat. This is another advantage to those forbidden bows you see in shops, because those curves are not only supported by cough(fiberglass), but also achieve those bends by lamination. So you may be onto something by splitting the limb like that. 

[PEARL DRUMS]

I am single minded when I hear "recurve". To me that means static with 70-90 degree tips. Everything else is simply reflex. That being said, I know alot of folks categorize sharp reflex as "recurves". So, depending on what side of that you stand on, working recurves can be very possible.

[Selfbowman]

Well said Pearl. Arvin

[simk]

Many thanks for all your contributions to this topic, which obviously can't be clearly divided in black/white. But I've learnt a lot...

One thing I'd still like to remark: When a bow looses artificial recurves/reflex it's not becoming "set". "Set" IMHO is, when wood is being overbendt and the structure doesen't return in it's naturally given position. I'f artifiacial reflex/recurves get lost by the time, the wood is returning in it's naturally given shape. It's not the same...artifiacial reflex/recurves are negative set.

And yes, i'm looking forward to present a nice pic of the bow after 1500 arrows.   

Cheers     

[Marc St Louis]

I am single minded when I hear "recurve". To me that means static with 70-90 degree tips. Everything else is simply reflex. That being said, I know alot of folks categorize sharp reflex as "recurves". So, depending on what side of that you stand on, working recurves can be very possible.

 

The old rule was if the string had contact with the limb then it was a recurve.  Anything else was reflex

[Badger]

  Mark, as far as I know that is still the distinction.

[gfugal]

Many thanks for all your contributions to this topic, which obviously can't be clearly divided in black/white. But I've learnt a lot...

One thing I'd still like to remark: When a bow looses artificial recurves/reflex it's not becoming "set". "Set" IMHO is, when wood is being overbendt and the structure doesen't return in it's naturally given position. I'f artifiacial reflex/recurves get lost by the time, the wood is returning in it's naturally given shape. It's not the same...artifiacial reflex/recurves are negative set.

And yes, i'm looking forward to present a nice pic of the bow after 1500 arrows.   

Cheers   

Set is any damage to the wood fibers that cause it to "stay bent" in any degree. It doesn't have to be string follow (which is deflexed limbs that remain in front of the belly, whether deflexed naturaly, by heat, or by set doesn't matter). It's possible to have 4 inches of natural reflex but end up with only two inches in the end. In which case you most likely got 2 inches of set, but no string follow. However, there is another occurrence where a bow can lose reflex and have it not be set. It's just undoing the reflex that was induced so to say and doesn't result in cell damage like set does. However distinguishing between that and set can be difficult. If it returns to its shape after time it's set. However, if it doesn't return it's more likely that other occurance, but it could also still be set. So to summarize again. if it returns it's set, if it doesn't it isn't necessarily not set, but could be the other occurrence (we should make a name for that).

This naturally relates to recurves because recurves are made of wood too. Just because they are recurvea doean't mean they are suddenly above the characteristics of the material they are made of. They can still theorectically get set, break, and suffer from all the other wood like ailments the rest of the limb may experience. Usually they don't because they are usually static and left thicker than the rest on purpose. But if we are going to have a truely dynamic limb then it is no longer static, but a working limb, amd if a working limb bends too much it will get damaged and get set. If the recurve completely un-winds that is a lot of bend that limb has to work for. Hence set can occur. However, I agree that it is less likely to occur than the other occurrence you mention where it just looses the heat induced recurve. So really I agree with you completely, i just didn't want the door to be shut on set entirely when it's still theoretically possible.