Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on July 03, 2019, 04:36:20 pm
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I've had this or at least a similar problem with a few bows so maybe you guys can help. I got this bow out to 40#@14" on the short long string. It was looking good and I was starting to think about bracing it. I decided to exercise it some so I pulled it a few times to 14", stopped and now it was 38#@14". I compared it with my tracing and it had around an inch of set. I thought I would take another look on the tree. I pulled it to 40# at 16", next pull was 17". I thought I would brace it so I put on temp nocks and an old string. Braced it and now I have a bow with a bit of hinge that pulls about 35#@26". It was like it just collapsed. I don't think the hinge can account for it all. Like I said I've had a similar thing happen with previous bows but I somehow saved them. This was like four pulls and it lost 10#. Any idea what went wrong? This one was doubly disappointing because it was part of my small supply of Plum.
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Did some of your reflex pull out?
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My first thought is wet wood. This is not your first rodeo so...must be something else.
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Quite a bit of reflex Don, those limbs have to travel pretty far to get braced, one small weak spot I can see being amplified with a design like that. You could shorten it, deal with the hinge and see where your at?
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Did some of your reflex pull out?
It did when the weight started going away but it was almost no set until then.
My first thought is wet wood. This is not your first rodeo so...must be something else.
It's had a year and two heavy heat treats so I don't think so.
Quite a bit of reflex Don, those limbs have to travel pretty far to get braced, one small weak spot I can see being amplified with a design like that. You could shorten it, deal with the hinge and see where your at?
Yeah it's kind of a stupid amount of reflex. I've used that caul before and never got that much reflex. I wonder if Plum holds it better than some others. At least until it doesn't.
Is there a possibility that having the limbs too thin and too wide would make tillering a little more touchy?
It's still got a lot of reflex so I could lose about eight inches of bow. It would be about 58" and have an inch or so of reflex. I'll do that. maybe six inches first. If the recurves are pretty much straight up like this and you pike it, basically just cutting of the recurves, does it have the same effect as taking the same amount of length off a straight bow?
Sorry for the blurry picture :)
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There's a good chance I just messed up, my minds kinda been on horn bows the last week or so ;D
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Don,
Looking at the updated picture it looks like just the reflexed outers pulled out...Don't see any set in the inner limbs...
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Rub a quick finish like oil, into the belly and look for chrysals. You may have simply found the elastic limits of that wood.
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Simple answer is you were asking more than the bow had to give. Once the reflex starts taking set all that extra reflex becomes counter productive even if you finish with a bow that has a decent amount of reflex. The bow will have more hysteresis. What was the target weight of the bow? Especially on that type of design not pulling full target weight from the start can set you up for a sudden collapse.
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DC, I had this same thing happen with a black locust bow. I didn't induce as much reflex as you did but I did heat treat in about 4 inches. Everything was looking great and even and I was exercising the bow and all of a sudden I had a hinge form in one limb.
Yesterday I tried to salvage the bow by significantly reducing the weight and not touching the hinge. There ended up being significant chrysals. Looking back, I think I did not draw the bow to target weight early enough. I should note that I had and still have an even taper throughout the limb with the hinge.
I am glad you posted this because I have been trying to figure out how this happened on mine too. I thought you may like to know you aren't the only one that had a sudden collapse recently.
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No sign of chrysals so that's a plus. 40#. I always pull to draw weight unless I'm sorting out a problem. This "all of a sudden" seems to be associated with RD's. And ,yes, I agree that this much reflex is excessive. I should have heated some out when I first steamed it in. I'm just so used to reflex pulling out that I got a little greedy. I've got two more pieces of Plum. I'll be more careful with them. :D
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I have the same thing happen on RD's more often than I like to admit. The string angles change pretty radically as the limb starts coming around. Best thing is to leave those outers just barely working until they have full come around to where you can see them with max leverage against them
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I've been using a longer long string for the initial tillering so that it does pull on the outers a bit. It seems to help some. I shorten the string as more and more of the string lifts off. Maybe the key to solving my problem lies in that area. Or like you say don't tiller anywhere the string is touching.
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If I'm going to pike and correct the tiller on this is there a preferred order. Would it be better to correct the tiller first and then pike it or vice versa?
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DC, thank you for posting this,, very informative,, (f)
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If I'm going to pike and correct the tiller on this is there a preferred order. Would it be better to correct the tiller first and then pike it or vice versa?
Honestly, I dont think picking will help. If you want to improve the bow, use heat to reduce the reflex. The wood has already been damaged by overly compressing it. The heat may help with more heat treatment, but you need to reduce the reflex to have any gains. Or, leave it as a short draw bow. You could also glue on a new belly....
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It definitely could be a lost cause and a new belly crossed my mind. I'll have to see if I end up with some thin strips of Plum. I did tie the string to the bow to see how much the weight went up and I was surprised. I'll get some numbers here in a bit.
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Not as dramatic as I thought. I just pulled it to 22" to maybe save what's left.
At 22" it's 23.5#
Piked it 3" off each end and its 27#
" " 4" 30#
" " 5" 33#
5" of each end leaves me with a 58" bow that might pull 40# at 26". I think I'll put it in the COS until I see if I can find some Plum lams. COS is getting kind of full :-[ :-[
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Hate when that happens. Especially on something like plum.
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Pulled this out of the COS cause I couldn't stand to see it there. I couldn't come up with some Plum to use for a new belly so I used Yew. I tillered the Plum portion down to about 25#@28" then glued on a 1/4" strip on edge grained Yew. I was leary of putting much reflex in because I think that's what caused my troubles to start with so I just glued it up as it wanted to be. In the grand scheme of things I should have glued in some reflex as the limbs went straight. So I wound up with a deflex recurve with about 1 1/2" total reflex. It turned out sorta OK because when I tillered it by the time I got down to 40#@28" there was only about 3/32" of yew left. If I'd put reflex in the limbs it would have been heavier and I might have ended up with bits of Plum showing through the Yew belly. I did side tiller a bunch, took about 1/4" off the width. Next time I'll thin the back down a lot more.
Anyway I chronoed it when I hit 40@26 and 3 shots got 172,171 and 173. Then I continued to 40@28. When I pulled it back on the shooting machine the arrow fell off just as I was releasing it. Nice clean dry fire from 28" >:( >:(. Didn't appear to be any damage so I squeezed the nock together a bit and tried again. I got 3 175's. Not much gain for 2" more draw. Maybe the dry fire screwed it. It does shoot nice and I think it's going to look nice also. I'l post some more pictures when I get it tarted up.
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And the FD. The second picture is Gimped to flip one layer to compare the limbs. There is a little reflex in the tip of one limb that makes it look a little stiffer but I think they are close.
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With these sort of bows you should deflex the handle. A deflexed splice is better than deflexing the fades. This reduction in necessary tip travel to brace allows you to have the reflexed outers for the energy storage. Parallel limb for a good distance which means you have plenty pf thickness taper again allowing more reflex to be kept by the outers (thinner wood can bend further).
I've just finished a similar elm bow. It is hitting 185fps with 10.5gpp arrows @ 27" It should be good for another inch of draw without breaking down any, it's 64 ntn.
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DC, when you say you pulled it to 16" on the long string, are you talking string movement or tip movement.
If you are talking tip movement, keep in mind that in a finished bow tips only move about 3".
Jawge
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DC, when you say you pulled it to 16" on the long string, are you talking string movement or tip movement.
If you are talking tip movement, keep in mind that in a finished bow tips only move about 3".
Jawge
Do you mean 3" of movement after its braced? I never knew that.
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With these sort of bows you should deflex the handle. A deflexed splice is better than deflexing the fades. This reduction in necessary tip travel to brace allows you to have the reflexed outers for the energy storage. Parallel limb for a good distance which means you have plenty pf thickness taper again allowing more reflex to be kept by the outers (thinner wood can bend further).
I've just finished a similar elm bow. It is hitting 185fps with 10.5gpp arrows @ 27" It should be good for another inch of draw without breaking down any, it's 64 ntn.
It is deflexed in the splice. About 5-6°. I normally do 11° but thought I'd try a little less on this one.
DC, when you say you pulled it to 16" on the long string, are you talking string movement or tip movement.
If you are talking tip movement, keep in mind that in a finished bow tips only move about 3".
Jawge
It was on the short long string so it kind of meaningless out of context.
I'm with Nasr here. I thought the tips(braced) moved about 1" for every 3" you pull the string. That would put the tip movement at 7-8" on an average bow.
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I think these Mark St Louis style bows will eventually dominate at the flight shoots when more people start showing up with them. My fastest bows have always had deflexed handles.
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They've sure worked for me. I've just got to wrap my head around tillering them. The first half dozen or so I made went really well. The last bunch have not gone well. Maybe I'm trying too hard. I should go with the Force ;D ;D
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? If you put say 12 degrees deflex in the handle and 4” of reflex in the last 6-8” of the limbs and make the bow 54-56” long with a 8” handle. What would a draw length be for this design with out pushing the limits to much? I have some great billets 31-33long. Been saving them for three piece take downs. Arvin
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Arvin, you can easily get 28 from that. The trick is width for your draw length at that point. How wide are they?
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Probably all at least 1 1/4 to 1 7/8 already rough tapered. They came from the bottom cut offs of my 69-72 inch pyramids. Real clean. Arvin
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I am not sure how many of this type of bow Mark has made from osage but I suspect it would really shine in this design.
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Yes I noticed ;)
I meant more deflex. The other points I mentioned are also key on this design.
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11° seems to be the magic number for me. I may try more on my next experiment but that would be getting to the point of no difference between braced and unbraced.
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11° seems to be the magic number for me. I may try more on my next experiment but that would be getting to the point of no difference between braced and unbraced.
I am kind of thinking as I type so I might be wrong here. But I would think with 11 degrees it would have a strong tendency to bend first right out of the fade so the wood would be a bit thicker in that area, a little more taper in thickness. The thicker wood could not bend as far as the thinner wood so it would work out ideal for not taking set and taking advantage of the low string angles that are maintained longer when a bow bends out of the fades. Really the best design there is I think.
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11° seems to be the magic number for me. I may try more on my next experiment but that would be getting to the point of no difference between braced and unbraced.
I am kind of thinking as I type so I might be wrong here. But I would think with 11 degrees it would have a strong tendency to bend first right out of the fade so the wood would be a bit thicker in that area, a little more taper in thickness. The thicker wood could not bend as far as the thinner wood so it would work out ideal for not taking set and taking advantage of the low string angles that are maintained longer when a bow bends out of the fades. Really the best design there is I think.
Certainly is the conclusion that I have come to after years of building shirt bows and studying them. The merits, reasons, science, and techniques of how to build them is what I'm taking notes on for the book I was talking to you about Steve.
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11° seems to be the magic number for me. I may try more on my next experiment but that would be getting to the point of no difference between braced and unbraced.
I am kind of thinking as I type so I might be wrong here. But I would think with 11 degrees it would have a strong tendency to bend first right out of the fade so the wood would be a bit thicker in that area, a little more taper in thickness. The thicker wood could not bend as far as the thinner wood so it would work out ideal for not taking set and taking advantage of the low string angles that are maintained longer when a bow bends out of the fades. Really the best design there is I think.
That's what I just said :)
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11° seems to be the magic number for me. I may try more on my next experiment but that would be getting to the point of no difference between braced and unbraced.
So what would you do if that was the case?
We appear to be going in circles haha, I have told you how to maximize this design :) Do what I've said and you will get the most out of this design. I think I made my first of these type of bows around 4 years ago and there have been quite a few since. The elm bow I quoted above is pretty much a perfected version of this design that incorporates all the things I have mentioned and i'll say it again - 185 with 10.5gpp @ 27 inch draw. I would have thought those numbers would speak for themselves ;)
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Bownarra those are great numbers without a doubt.? . I agree with the deflex relieving the compression on the inner limbs that forms set. But also what deflex is put into the limb takes some cast away. A straight limb bow with reflex that does not take set should store more energy. Correct me if I am wrong! Arvin
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11° seems to be the magic number for me. I may try more on my next experiment but that would be getting to the point of no difference between braced and unbraced.
So what would you do if that was the case?
We appear to be going in circles haha, I have told you how to maximize this design :) Do what I've said and you will get the most out of this design. I think I made my first of these type of bows around 4 years ago and there have been quite a few since. The elm bow I quoted above is pretty much a perfected version of this design that incorporates all the things I have mentioned and i'll say it again - 185 with 10.5gpp @ 27 inch draw. I would have thought those numbers would speak for themselves ;)
Those are rookie numbers. You gadda get those numbers up.
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11° seems to be the magic number for me. I may try more on my next experiment but that would be getting to the point of no difference between braced and unbraced.
So what would you do if that was the case?
We appear to be going in circles haha, I have told you how to maximize this design :) Do what I've said and you will get the most out of this design. I think I made my first of these type of bows around 4 years ago and there have been quite a few since. The elm bow I quoted above is pretty much a perfected version of this design that incorporates all the things I have mentioned and i'll say it again - 185 with 10.5gpp @ 27 inch draw. I would have thought those numbers would speak for themselves ;)
I'm listening and I appreciate your advise. I just have to try things. It's in my nature.
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11° seems to be the magic number for me. I may try more on my next experiment but that would be getting to the point of no difference between braced and unbraced.
So what would you do if that was the case?
We appear to be going in circles haha, I have told you how to maximize this design :) Do what I've said and you will get the most out of this design. I think I made my first of these type of bows around 4 years ago and there have been quite a few since. The elm bow I quoted above is pretty much a perfected version of this design that incorporates all the things I have mentioned and i'll say it again - 185 with 10.5gpp @ 27 inch draw. I would have thought those numbers would speak for themselves ;)
I'd like to see this bow you mentioned. Also, what are its stats?
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Very interesting!
Just had the same with poor ringed BL, I braced it higher and higher and lost more and more reflex...
Very good thoughts here, helped me to continue - seem to stabilize now.