Primitive Archer
Main Discussion Area => Bows => Topic started by: RT on May 11, 2014, 11:53:45 pm
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Would like to tap the thoughts on all bowyer ideas and experience when building a all-wood-bow with boo backing.
When you hit a "hinge" who do you do?
1)removing wood from the stiff area?
2) Knee bending on the hinge area?
3)heating that stiff area?
4)..........
Please share your experiences, much appreciated...
RT [Wink]
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Remove wood where it doesn't bend enough and leave it alone where it bends too much - to (roughly) quote Tim Baker (I think) :D
EDIT: It was actually Jim Hamm, but I'm sure Tim has said that also. Stumbled across it while reading last night.
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And use a tillering gizmo! It makes your life a LOT easier.
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I say build a time machine and go back to before the hinge appeared. Always works for me. Though the future has a way of correcting itself....
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Sometimes removing more wood every where but the hinge drops the draw weight too much. An alternative is to add wood over the hinge area by glueing on a thin strip or even tying on a strip of wood. I've even done it with a piece of split bamboo with a spiral wrap of strong cord. cheers fiddler49
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Bow building is all about solving a preventing problems. A hinge is a problem that a easily preventable if you go slow and keep a good eye on your tiller. Just like having a smooth and finely sander back prevents splinters from lifting(for the most part)
If for some reason you come upon a problem like an unexpected hinge. Depending on the severity remove wood from the stronger parts of the limbs and continue on.
If the belly is flat, and your in jepardy of coming in under weight if removing wood from the other parts of the limb, simply laminate a strip of cow horn to the weak spot.
A simple patch when done correctly can do wonders.
or
Start a new bow:)
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Once a hinge is apparent it's prob' too late.
Like most tillering it's a little of A with a bit of B and a dash of C.
I'd pencil a bit L (for leave) on it. Continue tillering, if the bow ends up under weight, maybe shorten it or heat treat the belly.
If the hinge is due to a problem in the wood or has chrysalled the maybe a belly patch will save the day.
It's all an opportunity to experiment and try new skills.
Del
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The best solution to a hinge is to cut bow into 12" sections where they fit nicely into a trash can. If you don't care about the looks we have a lot of solutions, wrap the area with something like linen for instance, sometimes you can inlay the same type of wood you have on the belly and continue tillering. I prefer the trash can method most of the time.
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I think removing wood everywhere other than the hinge would only be a problem if you've either ignored/not noticed the problem for the majority of the tillering or you've done something drastic during the final stages and caused an unsalvageable hinge.
Seems best to take it really slowly and get advice from people on this forum (NOT me :D)
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Depends on how bad the hinge is, small I do what others have suggested ,larger most times I use the Badger method. ;) :) The key is to get it gone,if you miss weight so be it, give it to someone that can use it and build yourself another. :)
Pappy
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I mark a big X where the hinge is and leave that area alone. Remove wood from above and below. Retiller the other limb.
To prevent hinges don't use power tools for final tiller. Once I string it, I'm using a scraper like tool. Also, remove wood in long strokes going past the target area by a little. In addition, take your time. No hurry. Check tiller frequently. Work thewood in with a few partial draws.
Jawge
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Make a kid happy , tiller it out for a kids bow and start another .
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Depending on your belly material, there is a good chance you have frets forming. Once you notice a hinge with a boo backed bow the damage is usually done. Boo is a very, very potent grass.
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Is this a hypothetical question? Or do you have a boo backed bow in progress with a hinge? If the later can you give specifics on the bow like materials(belly?),and stats? And even better pics will help a whole lot more,and folks here will be able to give you the right advice....otherwise everyone here is just pretty much guessing....vague questions receive vague answers that might not even answer the question or solve the issue...
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And use a tillering gizmo! It makes your life a LOT easier.
I have to say that unless you are building a perfectly uniform board bow, stay away from the tillering gizmo! when using a stave there is always going to be some profile character and the gizmo will tell you that there is a stiff spot when the wood may actually be bending too much! STAY AWAY FROM THE GIZMO if your bow has any character, it is meant for glue ups and board bows!
Cody
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And use a tillering gizmo! It makes your life a LOT easier.
... STAY AWAY FROM THE GIZMO if your bow has any character, it is meant for glue ups and board bows!
Cody
And straight staves.
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It's best to just try and avoid them all together, or at least catch them early. Before you get a hinge you will get an area or areas on the working limb that bend more the rest of the working limb. Mark that are and do not remove any more wood from there. Remove wood from stiffer spots until when it's bent the whole of the working limbs bend uniformly.
Too low weight, if your not a self bow purist, Nothing stopping you from gluing on a belly and/or back lamination. You then have more wood with which you can work the hinge out and not end up under weight.
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After reading the original post by RT, I'm not sure if he's talking about a 'hinge' he created or a 'hinge or dogleg' in the stave. He started this thread then has gone silent. I think he needs to speak up and fill in some info.
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We need pics!
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Sometimes to preserve your ego, you need to admit to yourself that the hinge is the only part of the bow that is built correctly and all the rest is just WAAAAYYY too stiff!
Screw up a few staves more than you can afford in money and time, and you quickly learn to go slow in the earliest stages of tillering and even a bit slower as you get closer to finished. Experience is a good teacher if you are willing to learn from mistakes.
Good luck!
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Thank you all for the feedback and sharing with me your experience.
I have my photos of the hinge stored in Dropbox.....I need to upload to photobucket and paste the URL so that you all can see the pix correct?
Pics will follow shortly.....
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http://s43.photobucket.com/user/robt188/libra
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(http://i43.photobucket.com/albums/e356/robt188/2014-03-30121802_zps440844b2.jpg)
(http://i43.photobucket.com/albums/e356/robt188/20140326_204155_zps48cf2b65.jpg)
It is badly hinged in both fades. Especially the right fade is not just hinged, but almost looks as if it's broken. Very bad tiller - I'm sorry. No way to fix this, IMHO. Start a new one and focus on floor tillering before you put a string on it.
What wood is the belly? It appears to have a palm handle, right?
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A good rule of thumb is that if you see a hint of a hinge at brace, it won't go away if you draw it back farther. >:D
Part of the problem is that you are using natural materials to make a pretend glass bow. That rarely goes well.
The belly lam has to be thin to make the curve in the fade and once it is thin enough to be squeezed into position, it's too thin to hold up when asked to bend in the draw.
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Im not seeing the same thing you are Jorad. Im seeing a fine left side and slightly weak right side.
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I don't know Pearlie, The right side almost looks like the back is bulging up in that fade.
Keep in mind there doesn't even appear to be enough wood in the fades to support the stress of a full draw even after the mid-outer portions are reduced.
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The outer two thirds of the left limb is not bending at all. All the bend is localized in the first six inches after the handle. But the right limb is the most worrying. It has a severe hinge right next to the handle. Exactly what PatM said: looks likes a bulge almost.
Jorik
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I was thinking that bulging area may be a poorly placed node?
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Still repairable in my eyes. May not make weight, but salvageable Id say.
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Hard to see the bulge on my little phone screen, but if its there its toast. If not, just getting the rest of the limbs working will make those hinges go away pretty quick. Obviously I don't want any hinges to work through, but given the choice i'd rather have it start to hinge on the inner limb than the outer. Inner limb hinges (usually ) can be eliminated without losing much draw weight. Outer limb hinges (especially whip tiller) mean a lot more wood and draw weight will have to be sacrificed to fix. Some closer pics of the suspect fade would help a lot on determining the approach on this one. Josh
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A good rule of thumb is that if you see a hint of a hinge at brace, it won't go away if you draw it back farther. >:D
What doesn't kill me makes me stronger....does NOT apply to tillering limbs!
Yeah, that hinge on the right is pretty grievous. The left limb would be salvaged, though losing a fair amount of draw weight. But to catch the rest of the bow up to the hinge at the right fade out is going to cost a lot of draw weight. Ok, life will go on. I say keep working on it, nothing worse can happen from here. Just understand you may be "fixing it to death" ultimately.
Before you go any further, go over the bow with a fine tooth comb and critique your glue up, the design, the execution of the design, any fine detail you can think of. Learn everything from it you can. Every bow should be a graduate level educational experience, even if it doesn't survive the process!
Good luck, brother!
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The handle area looks much to wide. How far have you got between the fades?
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It looks to me like the back of the bow actually dips slightly (almost like a small dent) just on the edge of the handle there on both sides. Not sure what that's about.
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http://s43.photobucket.com/user/robt188/media/Mobile%20Uploads/2014-05-07140505_zps2b9c8516.jpg.html" target="_blank"><img src="http://i43.photobucket.com/albums/e356/robt188/Mobile%20Uploads/2014-05-07140505_zps2b9c8516.jpg" border="0" alt=" photo 2014-05-07140505_zps2b9c8516.jpg"/></a>
This is the correct pics , left limbs where there is a maskin tape is the hinge area, left and right of the tape are the weak area.....
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Wrong pic all along? lol.
What exactly happened to cause those little divots? Power tools?
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You initially just posted the link to your PhotoBucket library (well, the link is almost working). I just had to guess that the most recent upload would be the bow that you were talking about. Since it fit a boo backed bow with a hinge, I presumed that is must have been the bow you were referring to. Wrong assumption.
The new picture (link to pic) shows a much better tiller. But there is still a complete lack of accurate information, RT. We need to know more info about this bow and your methodology before we can give you detailed advice. As you can read in these three pages, everyone is just guessing and making assumptions. So I'll refrain from giving you any advice about the tiller of this bow before we receive more information. Wood species? Unbraced profile? Technique used for laminating? Powertools yes or no? How did you tiller? Width? Draw weight? Is the belly flat?
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sorry for the confusion guys, i am new to posting pictures on PA linking it to photobucket.....
My reply #33 at 5:08:09 pm is the correct pics......regards... ;D
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Hi DarkSoul, the materials use are boo backing, maple core, riser and belly in boo......no, belly is raw boo backing thus not flat. bow is 59" NTN and form is 4" reflex after the glue dried. The core is pretillered before glue up and belly and back boo is 1/8"
all these are built using hand tools. hope i have cover almost all details.. ;D
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The problem is that the chosen glue-up is basically un-tillerable after it's glued up. Have you done some regular bows first?
There are a couple of guys on here or Paleoplanet who specialise in boo back and belly bows that can better help you with this type of bow. You really need to work out your tapers.
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Ok, well, we are getting some more necessary info. Boo belly huh? You didn't tell us that important thing before! :P This requires a totally different approach than a "all wood bow". Bamboo is not wood, by the way...
Since this bow has 4" of reflex, I still need to see an unbraced picture before I can judge the tiller. If the reflex is located AT the presumed 'hinge', you have a problem. Unbraced profile should match the full draw profile of any bow. 59" is also pretty short, at least for a 28" draw length.
As PatM said, since there is round, raw bamboo on the belly, you cannot tiller this bow the conventional way. You can only side-tiller a little bit, but not much. With such a bow, it is essential that you pretiller the backing, pretiller the core, AND pretiller the belly bamboo! You must pretiller all laminates before the glue up.
A build-along can be found here. (http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=001887) Read all you can about the subject.