Primitive Archer
Main Discussion Area => Bows => Topic started by: DC on December 13, 2019, 11:35:20 am
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I've had a few failures in a row and I'm a bit gun shy. Can you look at this and tell me where you would scrape next. Still on the long string. I would take even scrapes from the whole limb but I'm just not sure if I should be focusing on one portion of the limb.
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pretty profile, is it a lam bow?... assume left is top limb...appears longer.... I would scrap middle of both limbs to get them bending more... looks like bending out of fades already.. I like to leave my tips a tad stiff... I havent done a lam bow... so don't take my advice as gold... gut
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It's Boo backed Yew. Top limb hasn't been decided yet but I put the tentative top on the right. Even length limbs, probably the light, it's poor on the tree. I should fix that :D When you say it looks like it's bending out of the fades are you considering that it's deflexed in the handle?
PS I looked again and I can see the bending in the fades.
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A s u get a little further,,,it will come to u,.. :)
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A s u get a little further,,,it will come to u,.. :)
Especially if it blows up.
I'm not real experienced in that profile DC. To me I think I'd work on the inner third now. I don't think your moving much out of the fades. Take it with a grain of salt though. It seems to me your mid and outers are working nicely. Where have you been having trouble lately?
Bjrogg
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This bow doesn't have quite as much reflex as the last few. The last ones would develop hingey spots mid limb. When I examined them they were actually thinner there. I was scraping to much mid limb. Don't know why I never noticed. Everything seemed to be bending nicely and then, boom, a hinge. I'm wondering if I was scraping more in the middle because that was the highest spot. Anyway I'm trying to keep my eye on that. On another thread BJ and others mentioned starting with the outers first. I got going on this one and had a few doubts about where to go next. Thought I would ask.
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The reflex tricking ur eye
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Here's a pic to show how much it's bending
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Like I said DC. I'm certainly not a expert on this profile. I don't have it to feel it's limbs or watch them bend either. I think your pretty good but To my eye and what it's telling my brain from your pictures. It seems to me the mid is working nicely. I can't see much movement or bend out of fades or inner. Maybe slightly stiff in the very outer yet. I really hesitate to say anything though. I know you've done way more of these than I have and done really well at them. Maybe you want to close your eyes and run each limb bettween you fingers and see what they tell you.
Bjrogg
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The lumps on the Bamboo mess up my finger calipers :D
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The lumps on the Bamboo mess up my finger calipers :D
I never thought of that. I certainly don't want to lead you astray. Interesting delima.
You'll figure it out.
Bjrogg
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that looks good,, better to have it too stiff in the problem area,, so you dont get a hinge,, and fine tune it thinner as you go,,
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Looking at the last two pictures together like that it does look pretty good. It's bending a bit right out of the fades. I'd think you could probably continue with even scraps from whole limb for a bit. Get it that good to a low brace and study it some more. I know you certainly don't want to develop a hinge out of the fades. I got total confidence in you DC. You'll get a screamer out of her.
Bjrogg
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Low brace @ 20" lower(left) is a bit stiff. Second pic is reverse overlay.
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I think sometimes it takes longer for the wood to stabilize,,in those reflexed areas,, we scrape to make it even,, then it moves more than we think,, I think take off less than you think and work the bow a bit more than you think to see what it gonna do,,
maybe leaving it strung longer than you think,, I know I have to do that with the sinew bow sometimes,, to see what its gonna do,,
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Its looking good so far.
I'd leave it braced for an hour or so and mark where the set is compared to rested unbraced. That will tell you with unfailing certainty :)
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I got it out to 40#@28" and it's looking OK. I had a moment when I thought it had gone west but it seems to have worked out. When I was at about 20" or so I checked it against my tracing and it had taken a bit of set. A few scrapes ago it was fine. The strange thing was that it had taken about 1 1/2" of set in the same spot (mid limb) on both limbs. I avoided that spot and continued. When I finished it only has about an inch of set. I didn't know set could be reduced once it happened. The recurves are a bit aggressive(90°) and don't lift off. They are also too long so I have to cut the dead wood off the ends. This will cost me all my reflex. I'll chrono it this morning after the tipectomy.
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before you cut it off,, do you think you could draw it further,, :NN
so the tips can lift off,, it gonna shoot hard,, if it dont blow,,
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It's already got some set. Pulling it further will just make it worse I think. That plus my shooting machine will only go to 28". Since my goal is as close to 200fps as I can get with a 40#@28" I don't think there is any point.
Anyway here's a pic of the final tiller. I'm pretty pleased with it. I chronoed it and got a disappointing 180 fps. I think the lack of reflex and no heat treating this time killed the speed. I'm starting to run out of Yew so I'd better get my act together. I've got one piece of primo Yew that I'm saving for when I've figured my design a bit better.
I'll try again :D
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do you think the bow might be a bit long,, even with taking some set,,I am just thinking out loud,, and may be off about this, ,but if you drew it to 29,, it would tell you about the design,, if the bow is slightly overbuilt,, it would not take much more set and probably shoot harder than 180,,, if you are right on about the design, then pulling it to 29 would be a wash,, and no point as you suggested,, :)
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I pull 28" when all is said and done I like to pull past that like 29" or so. If she blows she blows up, but a good solid bow should be able to be pulled an inch past the desired draw length. Don't coddle it work it..!! ...........pull it like your life depends on it.
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Like I said, the machine only goes to 28. I can't draw 28 and even if I could I couldn't get consistent results with the chrono. I decided I would try something and I heated the bow to pull some more reflex into it. It went really nicely, just heated the belly until it started to move and cranked it down to the caul. No sign of the epoxy separating. I got both limbs done and then had company drop in so I have to wait until tomorrow to see if it will pull out or not. I'm half expecting it to pull out :D
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I couldn't wait and it all pulled out. I may try heating the back and see if I can get the epoxy to let go. Then re glue it with more reflex.
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The bow looks really good, if it is starting to take some set the added reflex will only make that worse. I would go a tad wider on the next one and look closely to see if you can get any inner limb wood bending more. You get a lot of inches of draw from the inner wood and it really helps to fight set if you can get the max out of it. But it can also backfire if you go to far because inner limb set is very bad.
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I tried scraping the inners and it just seemed to want to take set. I finally made the fades a little shorter and got a bit more working limb. It was an eighth of an inch wider but I trimmed that off because I thought the limbs were getting a bit thin. The original plan was wider and thinner but that went away somewhere in the build. I'm kind of limited in the width by the diameter of the bamboo. I can use the fat end of the log but the nodes are only 6" apart. I just measured and this one is 1 1/4" wide. The limiting factor on the next one is the width of the yew(if I use this piece) but I might get 1 1/2" wide.
I'm also thinking about making it longer. It's 66" or less on the last couple of bows before bending the recurves. Is there much to be gained by adding an inch? Two inches? When does mass raise its ugly head?
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66" to 68" seem to be the best number
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Maybe not as much recurves angle. Let them come off so it thinks it's a longer bow. Might help with the set?
Bjrogg
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I just stripped off the bamboo on one limb. Used the heat gun and carefully pushed a long wedge under it while heating. Once I got it started it just peeled off. took 15 min to half hour. I lose track of time :D. I can heat treat the belly this time. It's only about 1/4" thick so I should be able to get a good heat treat. I'm going to reduce the recurve angle then. I think it will just take a light sanding to prep it for re gluing. I'm going to go for just a touch more reflex than my best bow.
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Watching with interest. I'm not qualifies to give any kind of advice on these lam bows, but I think it looks pretty darn good from my perch.
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Sounds like a great plan (f)
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66" to 68" seem to be the best number
Thanks Badger. I'm not ignoring your advice. All will be incorporated in the next build. I just thought that this bow was a good opportunity to try tearing the back off an epoxied bow just to see if it can be done. I have so many bows like this that never get shot that tearing apart one may/will teach me something.
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Watching with interest. I'm not qualifies to give any kind of advice on these lam bows, but I think it looks pretty darn good from my perch.
If I stand back and really look at it it is a nice bow and a couple of years ago I would have been very happy with it. 180 is no slouch. I don't sell bows and have a wall full of them so if possible I'll recycle them to try and learn anything. I only have 10-15 years max left so I have to learn all I can if I want to hit 200. I really don't think I'll make it though, it's a pretty lofty goal.
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youll make it for sure,,, :BB
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DC...for what this is worth...I thought you were a youngster when you first came on. No particular reason other than you came across to me that way. Young spirit I recon. I'm not so far behind you. I have more behind me than in front of me, but I still enjoy the process. I hope for another 20, If I can talk my back into coming along with me.
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youll make it for sure,,, :BB
You have more confidence in me than I do ;D ;D
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DC...for what this is worth...I thought you were a youngster when you first came on. No particular reason other than you came across to me that way. Young spirit I recon. I'm not so far behind you. I have more behind me than in front of me, but I still enjoy the process. I hope for another 20, If I can talk my back into coming along with me.
Probably because I ask so many(dumb) questions ;D ;D
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It broke when I tried to reflex it after gluing and wrapping with rubber bands. About 6" from the tip there was a little knot. It didn't like all the deflex, heat treat and then trying to reflex it. So I'll try to keep that in mind for the next one.
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Pike it and make kid's bow or a short person bow? :BB
Hawkdancer
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No, I'll save the bamboo for another try.
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Dam shame she broke, but been thar dun that Scenario, those experiments are what they are, learn and move on to the next. My best bows have broke it seems that way anyway. In cast, smoothness of draw looks and performance..!
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good thing to document things they dont like,, easier to avoid next time,, :)
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It occurred to me that there was only about 1-2 hours between heat treating and reflexing/breaking. Might be able to write this one off to stupidity. I just got caught up in the moment and forgot.
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DC, Can you look at the glueline to see if any delamination happened?
As for me, the break at just 6 inches from the tip would not be a big deal. I would simply glue on a siyah. With modern glues, we don't even have to wrap it.
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It happened when I was doing the glue up. The glue was still wet.
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It happened when I was doing the glue up. The glue was still wet.
I see. I read about it and forgot. As you said, it was way too soon after heat treating. Unless I am steam bending, I wait several days before I bend heat treated bows. Good luck with your next one.
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It occurred to me that there was only about 1-2 hours between heat treating and reflexing/breaking. Might be able to write this one off to stupidity. I just got caught up in the moment and forgot.
That was one of my first thoughts DC. Might not have mattered who knows. Might have been better to heat treat on a caul and put your Reflex in at the same time? I do appreciate when guys post their problems to.
Bjrogg
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If I'd pre reflexed it I wouldn't have any Perry Reflex. I actually deflexed it a bunch. At rest, before glue up, it looked like it was almost full draw. I was pushing the envelope.
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Pre heated reflex,..could have Perry reflex,..if you reflex it more at glue up...I was assuming that is what Marc meant
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Even though I can't figure out how PR works I'm assuming it does work. If it does work and a little is good, then a lot is better, right? ;D ;D ;D ;D I'm also making the assumption that more deflex before gluing will be the same as a thicker limb. That I'm not really sure of. :-\ :-\
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I dont think you want to heat the core to shape before. a Perry reflex is supposed to be all glued up stress. Including the core.
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I dont think you want to heat the core to shape before. a Perry reflex is supposed to be all glued up stress. Including the core.
Not sure if you're answering my post but I was deflexing the core to add even more stress to the glue up.
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You want to heat it into reflex and add a bit in the glue-up. You're putting an effectively shorter backing strip on either way but heat treating the core into reflex is better than just bending it backwards.
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You want to heat it into reflex and add a bit in the glue-up. You're putting an effectively shorter backing strip on either way but heat treating the core into reflex is better than just bending it backwards.
Do you not think Perry Reflex works or do we just have different opinions on how it works?
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I think it works, ,and there seems to be a difference in opinion on how it works,,
Marc stated that he got better results reflexing the stave before putting the backing on,, either way, would work,, but some seem to think reflexing the stave , then putting perry reflex into that would give a better result,,
I made some 25 years ago,, I just had a straight core,, and then bent it into reflex when I glued the back,, with good results,,
if I was gonna do one now,, I would heat the core into reflex,, then put more reflex into it when I glued it up,,
then the chronograph would let me know if that was a good idea or not,, )P(
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You want to heat it into reflex and add a bit in the glue-up. You're putting an effectively shorter backing strip on either way but heat treating the core into reflex is better than just bending it backwards.
Do you not think Perry Reflex works or do we just have different opinions on how it works?
It works but likely not the way you think. Heat treating the belly into reflex as well just adds to it. Deflexing first and then bending the other way to glue up makes no sense.