Primitive Archer
Main Discussion Area => Bows => Topic started by: JWMALONE on March 20, 2018, 09:10:52 pm
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Hello Guys and Gals, this is what I got cooked up this time. A 64 inch t2t 1.5 inches wide for 8 inches then taper to .5 tips, handle area is narrowed to 7/8ths, 12 inch riser, Hickory backed ipe.
I used what I had just for the practice of assembling a R/D, curved riser, tip overlays and such. I have some good stuff but I'm saving it for the swap and one charity bow. So I had one 1/16 hickory backing and two hickory billets. I left the billets thicker than usual due to the thin backing. They both looked good but the coloring was slightly different. One side kept more deflex than the other, about a quarter of an inch. The tips are 3.25 and 3 3/8ths off the table, I'm sure this is going to cause me a problem. Just noticed that pic isnt very good, that bend is nice and gradual just like the last one. Oh yea belly is 1/4 ipe.
I'm sure its been done before but if I get the correct tip overlay material I can make them look just like flaked stone tips, pretty cool.
(https://i.imgur.com/up4zJH9l.jpg)
(https://i.imgur.com/MVtwOX4l.jpg)
(https://i.imgur.com/3dptBxql.jpg)
(https://i.imgur.com/QqzVFcNl.jpg)
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That looks good and should tiller out nicely, I use long riser sections myself but don't narrow them until I am confident that I won't need to wood. . You are turning into a bow making machine!
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Badger, I wanted 3/4 at the handle but played it safe and went with 7/8ths. Might wish I had left it wider. I'm still confused over the unequal deflex? I didn't use sister billets that may be the culprit?
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Looks good John. I wouldn't be too concerned about .25" difference in deflex. Could be difference in billets like you mentioned or the bottom of your handle could be a little off level causing the difference in measurement.
How thick are your hickory billets, just out of curiosity?
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Ben they were 5/16 tapered to 1/8th. That's all I had to work with. Wanted to see how that 1/4 inch belly worked out.
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That should be enough to get you to a decent weight. Look forward to seeing it bend (with you I'm sure that will be in a few hours, lol)
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Don't know bayou, its strange to say the least. Was going for another #45, we shall see. Decided to glue another piece on the riser area, get on up to 1 5/8ths thick just to be safe. Was 1 1/4.
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Its starting to bend pretty good, evenly any way. The tips are still 2 3/4 ahead of the handle.
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I doubt that little difference in the reflex will give you that much trouble. Trust your best eye on the tillering tree, and it'll likely come out in the wash.
Good luck.
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Springbuck , I over complicated it. I should have let it ride, it will be way under weight. Ill post when I'm through with it, one day I'm sure it will make a nice shooting bow for some young teenager just starting out.
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When I started for some reason I was intimidated by staves, chasing rings, etc... My first, probably 25 bows (?) were bamboo backed reflex/deflex bows. What a learning curve!
I was making each one out of a different wood, starting with boofloo tri-lams, then some ipe, then jatoba, then brazilwood, then osage, massaranduba, etc...., buying lumber off ebay at ridiculous prices..... copying fiberglass bows, basically.
One thing I absolutely learned was that R/D bows feel ridiculously stiff until you get about to full brace height. SO stiff.
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Yes stiff as all get out. I tried to get the limbs even and bending, I never pulled it to weight because there was no bend in the mid and outer limbs. By the time I got them to bend proper it was under weight. Lesson learned.
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DUDE! That's exactly how it happens! Sorry it didn't occur to any of us to warn you. That stiffness is down to geometry, not actual stiffness, though. Of course it is ACTUALLY stiffer, if you did the Perry reflex, than you would expect it to be for thickness, etc...
I actually remember really learning this while making a bamboo backed boofloo trilam. I always glue belly and core, then back into the same form for backing. Anyway, while tillering, I put a string on it that was too long, but short enough that the string touched the limbs for more than half their length, and the bow was semi-braced at about 2" at the handle.
When I tugged on that string it was SO stiff for 5-6" or so, felt like 80 lbs, I swear. Then the tips would come round and sort of toggle over, and you could feel the draw weight drop. When I got a real string on it at 5" + brace height, the bows initial draw weight was actually noticably LOWER than when braced 2", which seemed so weird to me then.
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I learned a good trick. Next time, mentally divide each limb into four segments. The minute you can see ANY bend in that 25% closest to the handle, the deflexed portion, STOP! Maybe catch the stiff limb up to the bending side, but hold it right there.
It only takes a tiny amount of bend in the deflexed portion to make this style work. Tape it off or whatever, but leave it alone. Move on to the next 25% until you can see it move WITH the first section, etc.... This will help you keep from bending the middle too much. About the time the first three segments are bending a bit, you can get a string on it and start perfecting the tiller.
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I really like your tips on that one John !
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Thanks guys, The first came out great #45. I sort of had the same problem. I think if had more experience I could have got #40 from this one. But I will book mark this post or wright it down for the next one. Thanks Springbuck.
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Yes stiff as all get out. I tried to get the limbs even and bending, I never pulled it to weight because there was no bend in the mid and outer limbs. By the time I got them to bend proper it was under weight. Lesson learned.
This is one of the reasons I put the bow on the tree when it is still far too strong, like 100# or so. Right from the beginning I am pulling to full draw weight. You can't hurt the bow if it is too strong even if it is uneven. R/D bows can still be finicky doing it this way but they are very difficult to finesse in to proper tiller. Every part of the limb responds to the angle of the string according to its own angle. On an R/D bow you have several angles going on at once, when it starts to break over your angle suddenly changes and the limb will start to cave in on you.
Once any area of the bow starts to bend too much you have no other option but to lower weight.
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I have a slightly different approach to tillering R/D bows. I guess it's sort of cheating, but I've had that exact thing happen to me countless times, and I can't for the life of me see the right tiller on these style bows. The more I mess with the tiller, the more I screw up the tiller.
So, I take detailed notes on every build. My goal it to get pretty close to final dimensions at glue up, maybe leaving the belly 5 or 10 lbs heavier than target weight. I get my thickness taper very precise before glue up. Once it's glued and I have all the edges rounded and the width taper correct, I start pulling to target weight on the long string. From here, I'm just cleaning up a couple flat spots and evening up the limbs, then reducing weight to reach my goal. I let the shape take whatever shape it wants to be not what I expect it to be. I know some may disagree with this method, but it has worked for me.
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Ben, I like that method if I could get it to work. Every time I try it I end up with a weak spot.
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I've only done a a dozen or so BB hickories/pecans/osages in a D/R forms but whenever I went tillering past flat in the reflexed area it was no good.The bow lost it's zing.The proper way to tiller these is to work your way from the inner limbs out?
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I've had the same experience BowEd with the reflexed areas. That's why I now "let it be what it wants to be". When I say I remove the flat spots, I'm talking about a handful of scrapes here, a handful there, not much at all. If I thickness taper precisely, I should have a nice gradual transition from deflex to reflex. I'm only looking for abrupt changes with my gizmo. I try my best not to make one whole area move one way or the other that's when I get into trouble.
The downside to doing it this way is that there's a lot of experimenting involved and you can't make changes to your design without starting over with experimenting. I probably have 10 experiment r/d bows that came in under weight, overweight, had wrong design, wrong materials, etc...
I'm not the person to answer your question on the proper way. Maybe one day I'll have seen enough of these and I'll develop an eye for the correct shape, but for now it's experimenting till I get it right.
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Ben, I like your method. Once you nail it down I think you will find you can apply it easier. I still look at every R/D bow as an experiment. I started staying away from the r/d and just went into a gradual reflex. I think the r/d is a slightly superior design when done right.
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Badger: "On an R/D bow you have several angles going on at once," Yeah, this is it, too. They are interrelated and at different stages from resting to brace to draw they effect each other.
BayouBen, that doesn't sound like cheating to me, but good planning. Probably took me longer, but I do the same. I thickness taper my belly or cores on a table I made using my power hand planer, then add kind of long reverse wedges to the tips. MY biggest problems came from bows that were WAY stiffer than intended draw weight so that by the time I got it down under ridiculous, I'd messed up somewhere.
Ben, what do you recommend for thickness taper? I never got very scientific about it, but say I take a healthy 70" long x 3/8" lam and I'm adding a 1/8"-3/16" backing and a powerlam. Do you taper it to half the thickness? Or, until it bends evenly to an arc?
I'll leave a foot untapered in the middle (so my fades will come off about where the limb taper starts) and thickness taper from there to just under 1/4" thick at the tips. Then, I may add back 1/8" tip wedges 10" or so long. Can you add anything to improve my method?
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I can PM you or we can start another thread. I don't want to high jack John's topic any more than I already have.
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Either. Thanks. I have a method, but I love learning more.
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No keep going, this is why I post all the stuff I get into.