Recent Posts

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Primitive Skills / A simple leather project
« Last post by bjrogg on Today at 12:57:24 pm »
I’m not very good with leather work.

I’m often afraid to cut up my leather and waste it on something that I don’t have the ability to create.

I found it easier to play around with my scrap pieces.

I find two scrap pieces and staple them together. The staples hold everything in place while I lace it together. One piece is longer than the other. The longer one is the backside and flap. The shorter one is the front side and where the blade will be carried.

Bjrogg
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Bows / Re: Snake bow
« Last post by Selfbowman on Today at 12:31:46 pm »
Guys I agree it’s a candidate for bow of the month but it was a bow blank from JiM Hammer and I won’t be doing the wrap on the handle. I will probably enter the black locust though. May not be as sexy but a faster bow at 10 grains per pound. And I am no photographer!
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Bows / Re: The best shape for a reflexed bow?
« Last post by Selfbowman on Today at 12:24:01 pm »
The design I’ve been using for years is closest to the third design. The speeds are close to what I get most of the time. I have had upward to 186 ft per second. Not often though. Interesting topic thanks for sharing. Notice the farther the tips get in front of the back of the bow the more speed. That’s with the deflex in the handle to help the stress on the inner limb.
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Bows / Re: Snake bow
« Last post by bjrogg on Today at 12:23:35 pm »
Thats a really nice looking bow. Perfect amount of wiggle to it.


Gotta agree. Nice wiggle. Should be a nice bow. Pleasant to the eyes too.

Bjrogg

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Bows / Re: The best shape for a reflexed bow?
« Last post by Tuomo on Today at 12:06:09 pm »
Simk: How do you optimize the front profile, and especially the tapers? The front profile is more of a practical problem, because in the model you can make it as narrow as you want, but in real life stability becomes a real concern. That’s the main reason I wanted to use the same front profile for every bow model.
As for the taper rate, I optimized it with strain distribution in mind. What would be a better approach? The 0.008 taper I used seemed to work well for every model.

Ryan: Yes, energy storage is mainly determined by the unbraced profile. That’s exactly what I wanted to examine, and of course the results of that difference also. All the “bows” had the same net reflex, yet they still behaved very differently.
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Bows / Re: The best shape for a reflexed bow?
« Last post by RyanY on Today at 11:35:01 am »
If we isolate the variables and assume that these bows are all evenly strained and 100% efficient then wouldn’t the difference come down to energy storage alone? I’m not sure what would make the difference just based on the unbraced profile. It’s hard to separate the real world effects that were used to making assumptions about such as strain, limb mass, hysteresis, limb vibration, etc.
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Bows / Re: The best shape for a reflexed bow?
« Last post by bjrogg on Today at 11:34:10 am »
Very intresting Tuomo.

I think I shoot that bow Bob showed and it was a very nice shooting bow.

What would work best scaled down to a 24” draw.

I would be interested in the best performing length and reflex shape for a 24” @ 50 lb natural material Selfbow.

I’ve only done one deflex handle with static recurves . It was more draw length than I could comfortably draw at 28” .

Would the static tips in my bow add to much mass ?

It’s kinda hard to wrap my head around all the mechanics of a bow. Something so simple. Yet so complex.

Thanks for sharing

Bjrogg
I’d like to know the best front profile for it too.
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Announcements / Re: Coming back !!!
« Last post by Pappy on Today at 09:13:13 am »
Glad to see ya back.
 Pappy
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Bows / Re: The best shape for a reflexed bow?
« Last post by simk on Today at 08:03:44 am »
Thanks Tuomo!
I'd say the results are intersting to get a general idea about these designs. The setback handle being worst and the d/r best will will most likely match with reality.
However: Having the front profiles and tapers not optimized will distort the outcome relevant. Especially having the same front profiles on all bows neglects specific advantages/disadvantages of these designs. The recurves need a lot more mass on the outers to stabilize than a self-stabilizing longbow. In my experience the theoretical advantages of recurves and other complex designs over longbows mostly get consumed with the additional mass required. Therefore I would cast into doubt  the "placements" 3-5 and also I think the gap between 1 and 6 is not that big.
 
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Announcements / Special deal for December BOM entrants
« Last post by sleek on Today at 03:21:19 am »
If you enter a qualifying bow into the December BOM your name will also be entered into the end of year giveaway. I really hope to see a huge BOM turnout this month!
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