Looking for a 400 yard shot

[sleek]

Great update Kevin! Looks awesome.

Thanks Ryan! Just trying to beat the bow you built years ago that won the contest for longest draw for its overall bow length! Haha.

[willie]

I think if  the crossection wants to cup, there is nothing you can do to prevent it, but consider a flat back that cups creating high edges. those edges will have a bit more tension than the middle of the back, so if the back is crowned some any cupping might not raise the edge enough to cause trouble.

or just plan around the cupping effect.

[sleek]

If you build a 64 inch version of the bows I make, and pull it to 35 inches, you will absolutely blow way past 264. Arrow shafts will be your hardest part.

can we see the unbraced side view of that design? sounds radical.

It didnt turn out as radical as I would have liked. Its split lengthwise in several spots while tillering which prevented me from applying the heat treat process I typically do. Its kept some reflex but none of the extra ai put into it. I blame the wood being likely too damp and not heat treated enough to hold the shape. It should have held the inch I put in it, it already had 1 inch naturally.

The reduced reflex is hurting my string tension and early draw weight. So, I dont expect much from this bow. But I will finish it and test it, trying again on a new stave.

Hopefully I'll figure out how to stop it from splitting.

[sleek]

I think if  the crossection wants to cup, there is nothing you can do to prevent it, but consider a flat back that cups creating high edges. those edges will have a bit more tension than the middle of the back, so if the back is crowned some any cupping might not raise the edge enough to cause trouble.

or just plan around the cupping effect.

Not bad ideas. This seems to be the only hurdle I have to test this design, so I'll give that a try too.

[mmattockx]

Another more simple idea is to remove the crown completely so its flat as a board on both sides. That may reduce the tendency for cupping as well.

Flat rectangular cross sections cup very noticeably, so I doubt that will solve your problem. I think a slightly crowned back will give you the least amount of cupping, but that is just a gut feeling.


Mark

[RyanY]

Flat rectangular cross sections cup very noticeably, so I doubt that will solve your problem. I think a slightly crowned back will give you the least amount of cupping, but that is just a gut feeling.


Mark

I was thinking the same thing. A very slight crown might help.

How wide was this one? I’m really surprised this would happen in sound wood.

[sleek]

This is 2 inches wide. The wood seemed sound but im not sure how dry it was. It cracked a lot when I put the heat to it for heat treat. That may be a factor. But this is the 3rd at least to do this.

[RyanY]

This is 2 inches wide. The wood seemed sound but im not sure how dry it was. It cracked a lot when I put the heat to it for heat treat. That may be a factor. But this is the 3rd at least to do this.

Yeah. 2” isn’t super wide IMO. If you look back at my red oak board bow recurve, it was 2.5” wide and had a similar bend. That one was super thin. I did crown the back slightly on that one.

[jameswoodmot]

Really enjoying this thread thanks for sharing

[sleek]

I got it back to a full 25 inch draw, the epoxy is doing its job holding it together. However its taken a full inch of set and thats unacceptable for a flight bow. It does shoot a 380 grain arrow 152 fps so its got what I'd call a low average speed. A good target bow or small game.

So, what happened? Too wide for its thickness, bending too tight a bend radius, and I think I had it bending too much in the inner limbs. As well as not being able to heat treat the bow the amount I like due to the glues intolerance to heat.

What am I going to do next? Well, Im going to build another 35 pounder but 50 inches long vs 48. The hope being the extra length will open up the bend radius just enough that it won't split. My normal bow length is 54, so im hoping I can make them shorter and harness benefits from the shorter length.

Here it is at full draw:

[RyanY]

It’ll be stave dependent but I’d go wider. I don’t think width is the issue here, especially in the inner limb where mass movement matters least.

[willie]

So, what happened? Too wide for its thickness,

not sure what you mean about "for it's thickness"

are you thinking thin and wide add to the cupping?

many short working limbed wide primitive bows often have lenticular crossections,

https://www.tapatalk.com/groups/paleoplanet69529/stone-age-bows-lenticular-crossections-questions-a-t68624.html