Primitive Archer
Main Discussion Area => Bows => Topic started by: campx on September 26, 2013, 03:34:56 am
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I found a pretty decent elm last year while out hunting, so it came home with me. Rough cut it out with bandsaw, and it cured all winter in my basement, no checking, no warp or twist.
So.....I like the idea of a lever-type bow, kinda Molly or Holmgaard'ish. At first, I drawknifed the limbs to 9/16ths-5/8ths thickness, at 2" wide, all the way down the limb to the lever. I went with a 7" lever, no reason why, not really close to the true Molly/Holmy ratios, just cuz. The lever tapers from 1" thick down to 5/8", 7/8" to 5/8" wide. Handle is 6", with 2" fades. 67"NTN.
Put a long string on it, tried the tillering tree. WAY stiff. So I decided to taper off the last 11" or so of limbs, blending them into the levers.
Managed to get a shorter string on it, at zero brace, threw it on the scale and tiller tree. It is pulling 50lbs at 20 inches, and the tiller is looking pretty symmetrical to my eye. This is where I am getting twitchy. Having built the grand total of 2 bows before, one of them being a vine maple jobby that I abused and built all wrong, but still shoots sweet at 42lbs, I am not sure exactly my game plan to get to a target weight of 60 lbs.......am I gonna have to scrape a bunch more wood from the belly of the limbs, or should I narrow them down? I am assuming that this thing, as is, would pull WAY high at 28".
What to do?
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If you are 50 @ 20 then you haven't got far to go.
Decide on a finished draw weight.
Pull to that weight or stop early if any problems.
Correct problem areas.
Pull to finished weight and assess again.
If your bow hasn't taken any set out to 23 -24 (assuming a 28 draw). Then yes narrow the limbs some. Narrowing increases strain if thickness stays the same. You should be aiming for around 3/4 to 1 inch of set any less and the bow is understrained.
Post some pictures and you might get more help.
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Yup...not far to go...if your concerned with it get some pics of it on here,otherwise were takings stabs in the dark,and have no clue where you need to scrape to get there? ??? If you think both limbs are perfect then its just a matter of ten to twenty scrapes full length of the limbs then checking weight and tiller and exercising it down inch by inch until you arrive at your desired weight
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Not sure where or when the idea came about that straight limb bows were "lever" type bows. In the old days it was always understood that recurves were lever bows
It would depend on what typed of Elm you have but I generally keep limb width to no more than 1 3/4" and if the Elm is very elastic then I go down to 1 1/2". In any case narrowing the bow by 1/4" at this point would not do much. If your tiller is looking good then keep exercising the bow and slowly extend your draw length. If the tiller starts to shows sign of going off then do the necessary adjustments. Once you hit your target weight, at whatever draw length, then you can focus on maintaining that draw weight by light scraping.
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You guys rule. Thanks for the quick reply. I'm working 12 hour shifts at the moment, I'll try and get some photos up in the next few days. This is the only photo I have at the moment, no tillering shots, sorry.
(http://farm6.staticflickr.com/5342/9918951473_b27819d98c_c.jpg) (http://www.flickr.com/photos/backinthecroft/9918951473/)
IMG_20130924_063410 (http://www.flickr.com/photos/backinthecroft/9918951473/) by CampX (http://www.flickr.com/people/backinthecroft/), on Flickr
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(http://farm8.staticflickr.com/7379/9951387373_be298f9377_c.jpg) (http://www.flickr.com/photos/backinthecroft/9951387373/)
IMG_20130926_063256[symmetrical] by [url=http://www.flickr.com/people/backinthecroft/]CampX (http://www.flickr.com/photos/backinthecroft/9951387373/), on Flickr
Threw it on the tillering tree and took this photo before I stumbled off to work this AM.
I heat-treated the last third of the working limbs last nite, and apparently it stiffened up one side..... it was a lot closer to symmetrical last nite before I went to bed!
More tillering to be done when time allows........
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Lookin pretty good just stiff on the right limb
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is the left limb the top limb?
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Zion, both limbs are same length from center of handle, so I haven't decided top from bottom yet.....
Speaking of handles or grips, what are your thoughts on angled grips ( I've seen photos in here where the grip is angled maybe 15degrees off of vertical) Pros and cons........ I still have a block of wood almost 2"X 2" to build a grip from.
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Did some tillering.
Sorry if this a not-so-great photo, I'm in a rush to post this and get to bed......
64# at 28 inches. I think I just tillered my first bow, PROPERLY, and by a method (TBB1).
Waddya all think?
(http://farm8.staticflickr.com/7443/9976674173_d1009f7fd6_c.jpg) (http://www.flickr.com/photos/backinthecroft/9976674173/)
IMG042_1 (http://www.flickr.com/photos/backinthecroft/9976674173/) by CampX (http://www.flickr.com/people/backinthecroft/), on Flickr
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It looks a little flat around the outer bit of the right limb, and maybe just a tad right in the middle of the left. It's the right one I'd worry about though; it looks like your inner limb is going to end up overstressed.
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You run a tillering gizmo on that and you'll see about your bend,but pretty good man,Your first bow and looking like that from the book.Congradulations.You've got a future in bow making son.......LOL.Have fun.
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Looks like there is a little twist in the right limb.
Eric
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A good clean shot of the bow ubraced can tell you as much as the fd.
Where is it taking set?
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Looking pretty good. I agree the right limb is a tad stiff in the mid-to-outer part of the working limb. Another thing you might want to do is radius the edges along the back. Elm is tough stuff, but leaving square corners like that is just asking for trouble, because the stress concentrates there.
When I see a bow on a tiller stick at full draw for a photo op, it makes me cringe!
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Thanks guys!
There is a slight twist in the right limb, very slight. I may try and get little more bend like you say, in that portion of the limb....or I may just say 'good enuff', no more tweaking, and just shoot 'er like that. Tomorrow I shape the handle.....