Primitive Archer
Main Discussion Area => Bows => Topic started by: upstatenybowyer on February 16, 2019, 06:01:10 pm
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Hi guys,
So I've been thinking a lot about how the outer limbs should look on a D/R bow that has a lot of reflex there. I keep going back to a comment Badger made on one I posted a little while back. He said the FD was about as good as I could get given the unbraced and braced profile. In that FD, the outer limbs looked straight, and others thought they should bend more. I decided to leave them as they were.
To me it makes sense that the outer limbs should look straight at FD if they're highly reflexed while unbraced. What are your opinions on this?
Here's one I'm currently working on that's shooting very fast and holding the reflex very well. Should the outers bend more? my gut says no.
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Hi guys,
To me it makes sense that the outer limbs should look straight at FD if they're highly reflexed while unbraced. What are your opinions on this?
Yes in a general sense. Highly reflexed is kind of a vague term. I think it's tied in with other things like bow length and draw length. The outers on an RD are basically working recurves and how much they unwind depends on how much they were reflexed when you started tied together with how far you pull it and how long it is. A short bow with a long draw length will go past straight and a long bow with a short draw length won't quite straighten out. My 1cents worth. :D
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I’m no expert on these reflex deflex bows. Matter of fact I’m puzzled at times by them. For what it’s worth, that looks damn good to me.
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This is a real common problem when there is too much bend mid limb unbraced. I prefer to see the bend much more gradual and increase more as it nears the tip in the unbraced profile. This design is hard to tiller out. They often get too thin in the mid limb and then start collapsing. You may have to get a little more bend mid and outer limbs.
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Its hard to gauge if the limb is working evenly...I am guessing if the taper is perfect,.the tiller is pretty close...and it will look how it looks,,.
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Thanks all. Steve, That makes a lot of sense. Sounds like I may need to adjust my caul to make the mid to outer limb transition a lot more gradual.
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Your outer limbs aren't highly relfexed. Your mid limbs are.
My advice... read what Badger and Brad said until it really sinks in.
Sometimes, the common problem Badger mentioned about there being too much bend midlimb of the unbraced blank is because it was glued up without pretapering the limbs. But it will still make a good bow if...
You can make it whatever profile you want, and tiller any part of the limb to work more or less as you see fit. But as you judge it, always compare how each part of the limb flexes to how IT looked unbraced. In other words, fight the mind's eye's inherent want to see that classic arc of a circle.
As Brad said, if you are meticulous about accurate width profiles and thickness tapering, in general, the bow will try to show you how it should look as its braced and flexed. You can vary from that a little, but don't fight it too hard trying to make it something else. The more you do, the more you risk what Badger mentioned, getting too thin/weak, causing set, collapsing in the overworked area.
Badger said, "They often get too thin in the mid limb and then start collapsing." They do. But this is not simply because that's where most of the reflex was glued in, but rather because folks try to make it something it doesn't want to be. They try to make the drawn profile look like the drawn profile of a different type of bow, usually a straight bow... and in order to get that 'inappropriate' shape, that midlimb area must be made too thin and weak.
I too prefer the reflex to be gradual and even from midlimb to the tips, or gradually increase.
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Your thoughts are truly appreciated DWS. I am definitely going to meditate on what Badger and Brad said. I've been slowly learning the underlying concept of what you guys are talking about, however, it's the nature of who I am that I end up really understanding something only by doing it the wrong way a million times first (a blessing and a curse if you ask me).
I think the way the bow above looks now is close to as good as I'm gonna get it, but going forward, I'll really try to spread the reflex out from mid limb to tip.
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I've still never tried one of these Jeff, but I find these comments interesting. I think the tiller on this bow looks like how I'd probably make one. I do like the idea of carrying your reflex slightly more gradual and carrying it closer to the tips. I suspect your outers could be working just a bit more than they are right now, but like I said I haven't done one of these yet. Nothing like learning by doing and making mistakes along the way.
Bjrogg
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Upstate, yours is not too bad and still plenty workable, I just think your bend is slightly abrupt. On the plus side if you complete your tiller without a hitch it is a very fast profile. If the other limbs end up too stiff it will be a tad unstable at brace. Builds like this are fun because the pucker factor is high!
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Great advice so far. I don't have much to add there, but when I find myself with a bow like this, where there's an uneven amount of reflex in one spot over the other, I rely heavily on tillering with slow motion video clips. I'll watch the video many times before I remove wood. I'll take a mental snapshot of the part of the limb I'm wondering about, let's say 6" of the midlimb, and I'll follow that part from brace to full draw in slow mo. Then I compare that to other 6" sections and you can get a good idea of how much it's bending regardless of how it "looks".
Like Brad mentions, if you know your taper is where you want it because you meticulously prepped it, and you are close in weight, let the thing come out like it wants. Preconceived notions of what these should look like should be thrown out the window IMO. There's too many variables from the form you used, to the amount of heat you used, the wood, amount of glued in reflex, bow length, etc, etc, etc, etc, etc, etc.....
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Good thread, good input here!
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Sounds like a book in the making Steve, "The Pucker Factor." :D
The video idea makes a ton of sense Ben. I try to do as you described while I'm pulling on the tree, but that doesn't leave a whole lot of time for careful consideration.
I've spent the last 24 hours redesigning my caul, attempting to even out the reflex, put it right where it should be, and making sure each limb is as close to a mirror image of the other as possible. Not sure if you see what I do from the unbraced pic, but the two limbs do not look the same to me. The reflex looks more gradual on the left than on the right.
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The video idea makes a ton of sense Ben. I try to do as you described while I'm pulling on the tree, but that doesn't leave a whole lot of time for careful consideration.
Yeah it's just easier to sit down and only focus on that area of concern and how much it's bending; not having to worry about pulling the rope and blocking out the rest of the bow profile.
I'm often surprised at how much that "stiff" spot at draw is actually bending through the draw cycle.
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Jeff, do you bend both limbs at the same time? I have a one sided caul that I made so I can bend different length bows. I sometimes bend the limbs one side at a time so that I can overlap the backing. Anyway I find that if I do one limb at a time I have a hard time getting them even. I get way better results(as far as eveness goes) when I use my adjustable caul and do both limbs at the same time. However with the adjustable caul I have a harder time getting more curve toward the tips. My adjustable caul is just a 2x4 with three posts(one fixed in the middle and two movable ones at the tips) and I use clamps to pull the limb down to make the reflex. Oh, all of this is for backed bows. For self RD I use a single limb caul and steam bend.
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I'm not really sure about this so take it with a grain of salt. I've had trouble with tillering some RD's where "all of a sudden" I have a weak spot. You've probably heard me whine about this before. I think I've discovered what causes it. I believe that if the string is touching the bow(hasn't lifted off yet) there is very little(if any) bending effort being placed on the part of the limb that the string is touching. With these highly reflexed bows if you are using a short "long" string and aren't braced yet this can be a good portion of the limb. More than half in a few of mine. You can carry on happily tillering, scraping the whole limb, and everything looks great. What you may be doing is scraping too much off the outers and don't know it because the string is touching the limb and there is no bending force on it. As the bow starts to bend and the string lifts off, "all of a sudden" there is a bunch of bending force on the weakened limb and you're in trouble. The work around for this is to use a "long" long string so that the string doesn't rest against the bow. This way there is close to full bending force on the limb the whole time and you can see what's happening. You have to keep in mind the problems associated with using the long long string and leave the tips a little stiff until you get it braced. For a normal bow the short long string is still the way to go but I plan on using a long string on my RD's from now on.
I may be out to lunch on this but I've had too many "all of a suddens" with RD's and I had to try something. I've used the long string on the last couple of bows and had no problem but not all RD's gave me trouble. This "all of a sudden" thing has only happened with RD's though.
OK thick skin turned to "max"
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That's interesting thought DC. I've never ran into that problem but never tillered that type of bow. Only static recurves with a very even gentle reflexed profile of a inch or two. It makes sense to me for whatever that's worth.
Bjrogg
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I've had trouble with tillering some RD's where "all of a sudden" I have a weak spot. You can carry on happily tillering, scraping the whole limb, and everything looks great. What you may be doing is scraping too much off the outers and don't know it because the string is touching the limb and there is no bending force on it. I may be out to lunch on this but I've had too many "all of a suddens" with RD's and I had to try something.
This is very interesting indeed. I've had this happen a number of times. I need to chew on this a while...
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Jeff, do you bend both limbs at the same time? I have a one sided caul that I made so I can bend different length bows. I sometimes bend the limbs one side at a time so that I can overlap the backing. Anyway I find that if I do one limb at a time I have a hard time getting them even. I get way better results(as far as eveness goes) when I use my adjustable caul and do both limbs at the same time. However with the adjustable caul I have a harder time getting more curve toward the tips. My adjustable caul is just a 2x4 with three posts(one fixed in the middle and two movable ones at the tips) and I use clamps to pull the limb down to make the reflex. Oh, all of this is for backed bows. For self RD I use a single limb caul and steam bend.
I heat/shape the reflex one limb at a time, but when I glue up I do the whole bow on a full-length caul. The problem is I wasn't meticulous enough when I made it and I think the two sides aren't totally the same. They will be though...
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Some may be wondering why all this fuss about the D/R design? The reason I've been so obsessed with it lately is that so far, no design I've made has even come close when it comes to speed.
BJ, I'd love to see what you come up with if you ever decide to give it a go. They are a ton of work, and not the most primitive, but the one's I've made shoot 20 fps faster than any of my selfbows. Still nothing like a selfbow though. )P(
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Jeff I was really impressed with the one Paulsemp shot at Elm Hall. My Simply Orange is a pretty flat shooter, but Knoll, Paul and I shot the money bear I think it was called. I forget the yardage exactly. Maybe 80 or 90 yards. Knoll and I both couldn't believe how flat Paul's R&D shot. Never seemed like a good fit for me with my short draw, but it got me wondering if I was wrong with my thinking. I could probably make a pretty short bow I'm thinking.
Bjrogg
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I have made some self bows holding some reflex that would shoot pretty close to 180 fps,, is that design really faster,, our you just like making it more,,,give me some numbers so I can appreciate what you are saying,, I dont doubt you,, I know I have heard of them shooting really well,,,,, just remind me,, :)
DC,, I think you are right about the tillering,, thing,,and I think its a bit difficult to see the tiller on that shape profile for me,,
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BJ, you could definitely make a shorter one. 8)
Brad, I guess I should clarify a bit. I've made some selfbows that have held reflex pretty well, and shot around 170, but from my experience so far (I am certainly not making any universal claims) no bow has ever held it's reflex as well as a tri-lam D/R. It must be all that glued-up surface area. It loses some, but with Steve's no-set tillering it's very little. The one above is only my 3rd successful tri-lam D/R, but all of them shoot in the high 180s. Not only that but I'm always shocked at the early draw weight factor. The string tension is crazy when braced. And then somewhere around halfway you can feel it get easier to pull. It's really cool.
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I think there is a stepping stone thing here. First there is a straight self bow. Then a backed straight bow will be a little faster. A self RD will be a little faster. A backed or lam RD faster again and I've found a backed RD with static recurves has been the fastest for me, so far.
I think the backed or laminated hold the reflex better because as PatM said a glued on back is shorter. I'd be willing to bet a nickel that the reason you lose some(I do to) is because the glue creeps a bit.
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Cool....thanks for explaining,,.those are nice shooting bows....
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Jeff Im enjoying your D/R fetish mine to ,whats not to like great performance smooth shooting I personally think the excellent performance comes from the early draw weight & superior string angle, as counter intuitive as it sounds I have found the designs with more deflex that are still holding positive reflex are the fastest ones I have made by a fair margin, I really like the design having a long draw it allows me to shoot a shorter bow with a superior FDC , but there is always trade offs in any design and there is some guys here that have made some highly reflexed static leaver bows that are ringing the bell at the same numbers ,I think the long bow shoots heavier hunting arrows at better speeds but for 10 gpp & under its hard to beat the D/R design !
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I'm just finishing the tillering on my lastest DR. It started as a Yew branch with about a foot of reflex. I cut it in half and spliced in about ten degrees of deflex. This gave me a DR with about 3" of reflex. I used the long string I mentioned above and started tillering. It's a knotty piece so it was mostly rasp and scraper work. I got it so the tips were a couple of inches past the brace height mark. In this time it had actually gained about a half in of reflex. I've had this happen with Perry reflexed glue ups but never with a natural stave. I decided to brace it even though I thought I had lots to go. It braced really easily so I went to full brace. Gave it a little tug and it felt real light. Put it on the tree and pulled. It went right to 40#@27". I was really surprised, I figured I had another hour of tillering to go. Measured the reflex and somewhere in the bracing process I had lost 1 1/2". Fortunately the tiller was good and all I had to do was tidy up the tool marks so it should be OK. Even though I used the long string the "all of a sudden" thing still bit me. I think the long string helped keep the tiller even but even so I came "that close" to coming in under weight. There is still something I'm not doing or doing wrong. Maybe the string was too long. Anyway just a little report on trying the "long" long string.
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u just didnt string it soon enough,, (lol)
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DC, I bet your bow also read 40# @27" on the long string. I always brace them 4" or 5" before target draw length. Your long string will measure just like your braced bow instead of watching the tip movement.
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I decided to brace it even though I thought I had lots to go. It braced really easily so I went to full brace. Gave it a little tug and it felt real light. Put it on the tree and pulled. It went right to 40#@27". I was really surprised, I figured I had another hour of tillering to go.
I would be surprised by that too. Bracing is always one of the most, if not the most difficult part for me. I'm shooting for 65# at 27" and I usually get the string on around 65# at 20" (although it feels like a heck of a lot more than). If I get to this point and the tiller is even, I'm usually home free. From there it's just even removal till I get to my target draw.
Looking forward to seeing that bow Don. :)
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You know, I kinda think you're right although I don't usually pay enough attention...
I went out and put a long string on and pulled it to 37@ 27. Lost a bit in the clean up, I guess. Then I put the proper string on at full brace and it was very close to the same. I noted the tip position with both strings and it was about and inch less on the long string. This is going to take some serious thinkin'. I've heard you mention this before but I never had the need to actually bend and measure.