Primitive Archer
Main Discussion Area => Bows => Topic started by: Dan K on August 22, 2013, 02:33:08 am
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Finally got my short string on my BBI recurve and found it is way out of alignment.
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_4632_zps6c4cc583.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_4632_zps6c4cc583.jpg.html)
I fear it is caused by the glue up because the Ipe is so flat and relatively easy to tiller. It seamed to pul straight and smooth on the long string. Now, I've never worked with Ipe nor have I every backed a bow so I'm in new territory here. I glued it with Titebond III
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_4631_zps2abef68b.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_4631_zps2abef68b.jpg.html)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_4636_zpsc08a5385.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_4636_zpsc08a5385.jpg.html)
What are the potential causes for this and is there anything I can do to correct it? If you need more pics let me know what you want to see and thanks for any help you can give me.
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Howdy, It looks to me like the limb pointing to the camera is twisting to the picture's left. More over it looks like the twist is in the mid-limb. I'm guessing this is because one edge ( the side the tip twists away from) is weaker than the other. It wouldn't show up much in a straight limbed bow, or be nearly as likely in a narrow bow. The correction is to thin the overly strong side of the limb. Then adjust tiller all over again, then sigh because your bow is now under weight, then....... Well I hope I'm wrong on all that last part. Ron
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Can you show a unbraced side view,and a front profile view and how wide it is? You might be losing lateral stability as well to what m-p stated...
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Is the limb still twisted when you unstring it ??
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Check your side to side thickness for consistency.
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In my experience it pretty hard to fix,thinning one side might work? I leave my tips 3/4" on recurves to the very last so I can trim them if alignment is an issue
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It was prob glued in alittle crooked.if trimming it on the belly side dosen't take it all out ,you could pike it a bit to where you have more meat to work with and move our center over opposite on both tiPs.
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Put some heat to it and start twisting. No good the way it is! Tite-bond glue will take more heat than you think. But it's probably not going to take all that much heat to get it to move. Luck............Art B
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other than what's already been mentioned, you could cut it and splice it back together at the handle or do a takedown. I think the key to deciding what to do is deciding why it's like that:
is it srtaight when unstrung? if so then like others said, you may have one dege of the belly thicker than the other.
is it crooked when unstrung? if so then you maybe glued it crooked?
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Thanks for all the feed back. Bin gone all day and just had a chance to post some more pics.
The correction is to thin the overly strong side of the limb. Then adjust tiller all over again, then sigh because your bow is now under weight, then....... Well I hope I'm wrong on all that last part. Ron
Thanks Ron, It is braced at about 50# so I have plenty to work with. I can start here and see what happens. If it works great, if not, I can try something else.
Can you show a unbraced side view,and a front profile view and how wide it is? You might be losing lateral stability as well to what m-p stated...
Here's some front views (sorry for the mess)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_4640_zps2442609c.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_4640_zps2442609c.jpg.html)
The tip furthest from the camera is the problem. It bends to the right when unbraced.
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_4641_zps57a9df5a.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_4641_zps57a9df5a.jpg.html)
It measures 1 1/4" at the handle and gradually tapers to 1/2"at the overlay tips. It's 13/16" at the base of the recurve.
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_4644_zps17dde293.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_4644_zps17dde293.jpg.html)
Can you show a unbraced side view,and a front profile view and how wide it is? You might be losing lateral stability as well to what m-p stated...
Thanks Blackhawk, can you expand a bit on the lateral stability?
Thanks Joec123able, check the pics, it's twisting pretty bad actually.
Check your side to side thickness for consistency.
PD, I think it's in the glue up not the tillering. I checked the belly and it's really flat and symmetrical from side to side throughout the length of the bow. How far out does it need to be to cause this much twist?
I think your right Bushboy, it was glued up a bit out of alignment. It wasn't as bad at first as it is now so maybe there's a compounded problem. If I pike it, I will lose the recurve so not sure I want to do that...yet!
Put some heat to it and start twisting. No good the way it is! Tite-bond glue will take more heat than you think. But it's probably not going to take all that much heat to get it to move. Luck............Art B
I'm thinking this would address the root cause but not sure if the laminate will make it Art. Have you done this before?
Yep aaron the take down is not a bad option and will be the final decision for sure.
I'm thinking if it's mainly caused by the glue up, I should heat straight first to address the main cause.
Does anyone have any guidance how to heat straighten a backed recurve with out breaking the bond on the bamboo?
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Was it shaped before glue up or was it nice wide lams glued up and then cut to shape?
Del
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From the looks of the unbraced. The glue up is to blame:( sorry buddy.
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Yup...majority bad glue up...try to make sure everything is aligned and in the same plane when gkuin up....also the narrowness at the base of a sharp reflex bend so far from the tips isn't helping things either and making it pull out of line even more because the string isn't tracking true down the center of the bow...and it is causing undue stress now to only the side of the belly over stressing that area...try to make your reflex more spread out and not so sharp confined to one spot...the string has to track dead center with that kind of a profile otherwise it will want to flip the string off(losing lateral stability)....I have made subtle corrections with dry heat on tbIII glue up..but they were osage bellied,and osage takes and responds to heat and change a whole lot easier than ipe...so I can't comment on whether not that will work or not...I know it doesn't respond well at all to heat pre glue up.....
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I've not used the TB glue with that combo Dan. But that glue may be your saving grace here. Like Chris stated, if that were Osage it wouldn't be a problem. Ipe don't respond well with heat. So you may have to hope that you can make the correction by softening the glue and repositioning the components.
I just had a friend make a 3hr drive to do a 5min correction on a bow very similar to yours. However, it was boo backed Osage. I think he was dumb-founded at how easy it was. Course I'm not the timid type when working on other's bows >:D! Art B
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Was it shaped before glue up or was it nice wide lams glued up and then cut to shape?
Del
It was glued up full width 1 1/4" Del.
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Should I heat straighten the limb or in the handle?
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The twist is in the limb... so straighten it in the limb. Hopefully steam won't over heat the glue?
If it was glued full width, maybe it needed exercising before being narrowed too much at the tips.
Sorry if that is just being wise after the event, but anything with reflex can be twitchy.
Could just try jigging it up with a weight pulling the twist out and leaving it for a few days... maybe with some v gentle heat, like a light bulb near to it.
Better to try the gentle persuasion before resorting to something that might leave it MBR.
(Mended Beyond Repair ;) )
Del
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Good advice Del! I'll start with a light bulb and see what happens. You mention steam, what is the best kimd of heat in this situation or does it really matter? Pros and cons?
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The big advantage of steam in this situation is it won't get over 100 dgrees C. A temperature controlled heatgut would also be good for something like that, I had one which wasn't too expensive... I ruined it by switching it off and not leaving it upright to cool... the innards melted >:(
It also might be worth gluing up some scrap timber to test how the glue reacts to steam.
Del
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Howdy, I didn't seriously consider that the stave may have been glued up twisted. I mean, I might glue crooked, fail to check or draw a new centerline and then trim to profile anyway...... but nobody else would do that! Hopefully controlled heating and counter twisting will correct things, but the Ipe belly might resist such efforts. Ron
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I'd do what Art/Del said. I actually have done what Art said, and it worked beautifully (though not with Ipe). Titebond is supposed to soften at about 150 degrees I think, but will be pliable at lower temps. Even at 150 it doesn't just let go (in my experience anyway). Just make sure you don't cook the ipe (if using dry heat, crisco works nicely here), take it easy and be patient (not my strong suit), and it's ok if it takes multiple sessions to get'r lined up.
You might try using a high wattage light bulb as Del mentioned with the bow in the form you used (I worry about losing/changing the reflex profile with heat), but secure the offending limb about as far off center on the other side of where it is now. Surround the whole area with a mini makeshift hot box and monitor temp. Maybe... it could work! ??? ;D
Good Luck!!
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Just to make sure I'm clear, I can heat and check for results and if it hasn't met my expectations it's okay to heat again repeatedly. I'm not sure about heat bending past the twist because this really isn't a bend its a bad glue up. Don't I want to heat and straighten to location and when the glue hardens again it should hole in that position? I just don't want to switch the problem from one side to another.
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Dan, you're going to have to go way past straight to accomplish what needs done. Heat it, twist it, and pull it out and look at it. Do not leave it in place. For example, I like to see my correction stay a little past straight, and it if holds there, I've bring it back to where it needs to be. That way there's no question of any spring-back and having to reheat and do again.
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Okay folks. Here's a picture of my set up with the lightbulb and weight pulling the twist in the opposite direction.
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/null_zps269a319e.jpg)
Looks like it will work as long as the bulb gets hot enough. 100watts. If I'm doing this wronged me know! Thx
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Hope it works, Dan. If it doesn't I would shorten the bow, shorten the handle (or eliminate it), and go from there. MOo
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The light bulb worked! Thx Del.
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/null_zps5760df71.jpg)
The limb in my hand is not the bad end although I'm going to straighten it too now that I now how.
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/null_zps2211a47c.jpg)
now to scrape the rind off the boo and tiller. I was told to be careful and not damage the nodes. How clean do you need to get them and how do you know if you scraped to far?
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Hey Hey......Happy days are here again......LOL.Nice when a plan works.Congrats.
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you might just want to leave it.
But just scrape a little until it isn't smooth- the rind is a consistant color, the fibers look like effingglass.
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Cool, I will have to remember this one for sure! Nice save, is that light bulb a higher watt one?
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Well done Dan :).
It may be worth repeating the treatment, to over bend it slightly, in case it tries to relax back?
Del
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Cool, I will have to remember this one for sure! Nice save, is that light bulb a higher watt one?
100 watts
Well done Dan :).
It may be worth repeating the treatment, to over bend it slightly, in case it tries to relax back?
Del
I did and went a little too far. Had to bring it back in and let it set for a couple days to stabilize. Put the short string on and it stayed true. I'm thinking once I get the weight down it will reduce the lateral pull on the recurve areas. Hopefully it will fling an arrow!
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Nice save.
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Glad it worked for ya!! Best of luck with the rest of the project :)
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Thanks for all the support! I'll keep posting progress just for grins.
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I know some folks are out there learning along with me and wanted to share some information. Did some research and found that when you glue up a BBI (probably any laminate for that matter) you don't want to have all your clamps on one side. This could put your limb in a twist! Went back and looked at my pics and sure enough...I had most of my clamps on the same side. Can't say for certain this was the cause but makes sense. Some others with experience can add to this but I think you should stagger your clamps side to side every other one.
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_4497_zpsbde8493c.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_4497_zpsbde8493c.jpg.html)
Now I need some help. My upper limb, the one with the twist that I was able to get out, is no longer symmetrical with the bottom. In the pic you can see it lost some of the deflex and gained some reflex.
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/null_zps3788274b.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/null_zps3788274b.jpg.html)
Should I try to heat bend the reflex and or deflex to match the bottom keep tillering?
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_4718_zpsd6fdb15a.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_4718_zpsd6fdb15a.jpg.html)
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We'd some help here folks! Not sure what direction to take with this recurve. I'm thinking I should due some more heat straightening but not sure if it may even out with tillering. ny help would be appreciated.
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Tillering R/D bows is a tedious and iffy... Heat bending IPE has never worked for me but it's said there are like 100 species of trees whose lumber goes by the name IPE. Maybe the glue creeped a bit due to the heat? Since it worked of sorts the first time, I'd try it again but on the other limb since tillering out that much difference and that much reflex in the limbs is going to be pretty touchy.
Did you tiller/thin the limbs any before you took that last set of photos? It's counter-intutive but reflex can increase due to thinning the an area with reflex- especially with a belly that isn't tillered before glue-up . Lots of exercise to register the change sometimes helps.
Some tips to avoiding limb twist when glueing-up:
1) Those rubber strips used to wrap a bow can cause twist. The diagonal wrapping can prevent the belly from evenly seating on the form. Hopefully this is shown in the attachment. I like 4" wide stretch wrap like shown in the attached pic.
2) After getting a bow glued and clamped to the form, use winding sticks at different locations along the limbs to check for twist.
Please post on how it goes!
c.d.
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I'd like to put a close to this event, show off a little and thank you all for your help. After I took it to full brace the twist came back. Thanks Gordon for showing me how to tiller a twist! It worked! I lost a little weight (the bow that is) but string aligns close to perfect and has stayed true for over 400 shots now. Tillered to 48#@28.
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_8376_zpsa5cd18be.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_8376_zpsa5cd18be.jpg.html)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_8386_zpsa6ad8fce.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_8386_zpsa6ad8fce.jpg.html)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_8397_zpsfaa6a4c8.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_8397_zpsfaa6a4c8.jpg.html)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_8394_zps96e66d9d.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_8394_zps96e66d9d.jpg.html)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_8392_zps594e8206.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_8392_zps594e8206.jpg.html)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_8382_zpsde84d5ce.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_8382_zpsde84d5ce.jpg.html)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_8384_zps5b7c66cf.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_8384_zps5b7c66cf.jpg.html)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_8381_zps3fd9c057.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_8381_zps3fd9c057.jpg.html)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_8377_zps13c7f663.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_8377_zps13c7f663.jpg.html)
(http://i1303.photobucket.com/albums/ag157/dankirkpatrick/IMG_8380_zpsd230b4eb.jpg) (http://s1303.photobucket.com/user/dankirkpatrick/media/IMG_8380_zpsd230b4eb.jpg.html)
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That's a fine looking bow! Way to save that one, Dan. Can't wait to see it in person.
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As you can see though it still isn't straight!
Lesson for the next one - make 100% sure you don't induce twist when doing your glue-up.
Also be mindful of the crown on the bamboo when preparing it.
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Thanks Weylin, being a lefty you can shoot this one. ;)
Thanks Mike and you're right. It is a bit off but shoots straight and smooth all the same. Ill be watching closely though for any movement. I'm happy for my first attempt and learned so much along the way to add to the next one.
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Looks very nice, Dan.. Congrats I'm sure you learned a lot on this one and the next bow will be even better.. Roy
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Wow, thats one sexy bow right there. Can I ask you what finish you used? It looks great! Yeah, I hate twist. Only thing I do is remove wood on the stiffer side (the side pointing farther away from the bow) until the sting is centered. Yall ever have a bow where the string is centered, but then the outer limb is twisted, to where you can't really do anything? Thats always fun too, :). Very nice bow, looks fantastic!
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What Roy said.
I shot this bow yesterday and it flung my 650 grn arrows nicely. Its taken just enough set to show that it is operating very efficiently. The performance and workmanship is way advanced for Dan's experience level.
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Part of your twisting problem has to do with the shape of your bow, your outer limbs are pretty straight and the curves starts quite a ways in from the end and is fairly abrupt. On the next one if you can get just a slight more curve in the outer limb and make your mid limb bend just a tad gentler it wont have quite as much tendency to want to twist.
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Thanks Badger, I thought the same thing. I lost some reflex in my tips during tillering. If i moved the bend out a bit and tightened it a bit I think it'd perform better and not give me as much trouble.
toomanyknots -The finish is shellac but it's only the base coat. I plan to finish it with tru oil but the overlay (orange wood) is Padauk and bleeds really bad with oil. Shellac is a fantastic sealer. Thanks for the complement.