Primitive Archer
Main Discussion Area => Bows => Topic started by: ionicmuffin on September 02, 2012, 06:44:28 pm
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This stave i just received last Thursday! This stave was gifted to me by Bryce, so a big Thank You to him! I have run into a small problem that i would like the communities opinion on. There are several bumps and lumps on the back of this stave, and i am not sure how to remove wood from the belly to maintain a balance between the thickness of the limb and between each section of the limb i remove wood from. My idea is to use my finger to trace along the back of the bow while on the sides i use a pencil to translate the bumps on the back to the sides so i can remove the proper amount of wood.
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More pics
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I think you've got the right idea. You want to follow the back as best you can. I use the method that you described with the finger and the pencil. it works pretty well for me. then once you get the bow roughed out you can also check the thickness taper with some outside calipers if you feel like your fingers are deceiving you.
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Yep that how you do it.
Vine maple is tricky like that.
It can make for a tricky tiller.
In fact I forget the tiller tree and get it right from a thickness stand piont.
Spend most of your time BEFORE you string it, then exercise, exercise, exercise.
Also VM often has a propeller, it can give ya false readings on a tiller tree. Make sure you view the bow from many angles.
If your thickness is good trust that, not your eyeballs.
I recently did a VM just like described, never touch a tiller tree/stick.
Started 4" reflex, 100+ shots later, 3" reflex and the crazyiest tiller you've laid your eyes on...
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This stave has 4" of reflex atm. it is only 60" long though and i have a 30" draw, so i will be flipping the tips to avoid any stack. even if i cannot get it to 30" draw i will still be happy with 28". I just went ahead and thinned the limbs and will repeat now that the whole stave is at least 1" or less thick. i will be repeating until it is about the thickness that it needs to be.
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Is this bow going to bend through the handle? If not I think you are asking alot of this stave to bend 30". Flipping the tips will effectively shorten your working limb, adding more stress and inducing even more set. I'm not sure you can afford it with such a short stave and such a long draw length. I'm not an expert on what shorter bows can take but those are my suspicions.
Are you sure your drawlength is 30"? I don't mean to doubt you, you could be a very tall person but most people tend to overestimate their drawlength and are often quite surprised when they measure it accurately. Put a clothespin towards the end of a long arrow and draw the bow to your normal comfortable anchor point so that the pin slides along the arrow at the back of the bow, measuring your draw. take the arrow off and measure the distance between the inside of the nock and the pin. Do it several times so you can throw out the measurements where you were overstraining. A friend of mine just did this recently and found his drawlength was a full 2" shorter than he had always thought.
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i plan to have it bend through the handle a bit, i was planning to have all but 2 inches at the tips doing work, also, i will check my draw, at first i had thought it was 32" but i was wrong. Time to remeasure, we will see what it is and i will re-post.
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I know a guy that has a 32" drawlength but he's one inch shy of 7' tall. :o And I think that's his compound bow drawlength which tends to be a little longer than a longbow drawlength.
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so i have concluded after performing the described method above, that i have a draw of 29 1/4 most constantly(like 5/8).
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Hold off on flipping the tips.
The finger and the pencil thing is how I do it. Sometimes with a T square.
Off to a good start.
-Bryce
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2 more pics of areas i had been working on to follow the lumps
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In my limited experience I have found that it is better to leave a little extra meat around those lumpy knots. I think it is a good idea to establish your thickness taper with the pencil/finger method, but don't get carried away trying to dish out the belly side of a knot. I think the treatment of lumps in the second picture you just posted looks great, but the first one I would be a little worried I was dishing in a bit deep behind that knot. that said, pictures can be decieving, so trust your gut over anything I have to say. :D
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good advice so far. i use calipers to judge the thickness taper in lumpy VM. If you leave too much extra meat on the belly side , you are effectively shortening your working limb by making that area stiff. It's hard to jusge how much the lumps are bending- so as someone else stated, make sure to get the thickness tapering throughout the limb. Here's another trick: draw a straight line on the side, right at a bump. bend the bow a little on a tillering tree. now hold the straight edge up to this line and see how much it bent. Do this every 6 inches along the entire bow for an almost foolproof tiller! good luck!!
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oops in those two photos, i am showing 2 different sections of the bow, but you get the idea. the blue tape arrow on the straight edge helps measure the bend.
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I like that tiller trick.
I never was on for a 'tiller gizmo', most of the bows Ive made are just to wild for it to work.
Your method is a great alternative.
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Be carefull around those dips you will hindge if not paying close attention. I would recommend ignoring the dips and get a good arch, then go back to those dips and remove weight from those areas carefully.
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alright, i have just barely got it bending right now, it would probably weigh in at 50 lbs at 8-10 inches if i could get it that far. so i still have a LOT of wood left to work with.
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looks like it is nearly floor tillered, the over all thickness is 3/4" at the fades, it tapers to 1/2" at the tips and then there is about 1"-3/4" thick at the last 2 inches of the tips. looks like its going to be VERY fast because there will be nearly no mass when im done.
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just weighed it and its now 21oz and will probably drop quite a bit more when its fully tillered considering that its just gotten to floor tiller.
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So, i just weighed the bows draw, at 12 inches with a loose string its hit 30#. and my goal is 50# @ 28"
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If you need help with the till just throw some pics up with it in the tillering stick and it will be easier to help.
-B
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alright, i have just marked out 1 inch sections along the limb, then i marked it if its too think, and if its the right thickness then i don't mark it, then i can remove wood from those sections thus giving me a taper.
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pics of it at rest and then front, then back. Tell me what you guys think, I will say, it is pulling 45# @ 15" of draw.
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Bend looks pretty good, but I wouldn't put much in the weight at x draw length, when you have a long string on. At the point you are at I move to a low brace to continue tillering.
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when you use a long string, make it as short as possible- yours is a bit too long.
i think you may still be too stiff for a low brace.
i would take down the tip thickness- you won't need all that thickness, even if you do go for flipped tips ( which i think you should not flip the tips).
good job so far!
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So by tip thickness you mean the last 2 inches that i left thick right? I have found a brace height that is considered low brace and will use that tomorrow to help me tiller it.
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I just found my way over and I think the build is going very well. I agree there is more tillering to be done before risking a low brace string up, but I do think you are on the right track and are doing well. Keep a close watch on those areas where the "lumps" are close together. One of them looked like a prime candidate for a hinge. I'm not saying there actually was one there but I can certainly see it happening.
- Mike
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Looking pretty good so far,as far as tapper I usually let the tiller determan my tapper especially on a piece of character wood like that one. Like others have said shorten the long string as short as you can get it,it will give a more realistic look at the tiller. 30 inches is going to be a lot to ask of that piece of wood. :) but I get surprised every day around here. ;) :)
Pappy
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at this point yes about 30, though i will do my best to not draw that far. Ill get to work on it now, plenty of time to get a good portion done today ;D
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OK, i have a problem. I removed too much wood here at the tip :'( I assume i can fix it because there is still wood that i can remove nearer to the handle. I am not sure what to do at this point. i wont work on it further till i know what i should do. I imagine that this bow may have to come out at a much lighter draw because of this.
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i was just thinking, what if i heat treat the belly portion that has the hinge, since there is less wood i would need something to make it stronger in compression. either that or add more wood?
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Let us see it on the long string with a gentle pull until hinge shows. Looks like it's still 1/4" thick. Go sloooow tillering the rest of the limb.
Don
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Here are pictures of the hinge... and the other limb, which looks great.
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Thats the reason you don't try to follow the dips while tillering.
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I hate to say it man, but I think that one is gonna hurt. The amount of wood removal needed to fix that hinge is gonna seriously drop your draw weight. Heat treating is an iffy fix, it may provide a short term, local solution at the hinge, but my opinion is that it's unlikely to solve this problem.
Gabe
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A thought....That should be the static part of the limb at 3 inches or so from the tip. Should have been left thick to start with, but...glue a belly lam to the tip. I have an Osage bow at 64" inches that I nearly snapped the tip off when heat bending. I took Eastern Red Cedar (very light, good in compression, grows everywhere here) and fashioned a belly lam. Actually 2 of them so the tips would match. Sanded, glued and and thinned it as needed. The bow has shot hundreds of arrows over the years. You can't tell there was ever a problem.
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well, what wood should i use? i dont have much else other than some plumb or maybe rhododendron wood which is tough as nails, or just some of the original wood. What do you guys suggest i try?
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Thats the reason you don't try to follow the dips while tillering.
depending on your skill level slimbobs idea would work, i think i'd just pike it and build a young boy or girl a bow and chalk this one up as practice, Bub
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Thats the reason you don't try to follow the dips while tillering.
depending on your skill level slimbobs idea would work, i think i'd just pike it and build a young boy or girl a bow and chalk this one up as practice, Bub
Well, i guess i could, just to let you know, this bow is only 60 inches long anyway, so thats pretty short, The other thing i could try if non of these things work, is to remove enough wood to put a full lam on. Maybe thats what slimbob was talking about.
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Any wood should work. Keep it lite so it doesn't slow the bows performance. I would think even something like spruce would work since you can adjust the thickness for strength. Looking at the picture, I don't see why it won't work. Might be a little tricky getting the two surfaces to mate up well, but you should be able to get 'er done. Leave the lam thick so you can come back and thin it as you need. I simply feathered both ends and sanded till I had a good fit. I used epoxy, but someone may suggest another type of glue.
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I assume epoxy because it has a high strength bond. That makes sense. In any case, i was just thinking that if its only at a little less than half draw(before this happened) and it was about 40-50 lbs then maybe if i were to tiller the rest of the limb i wouldn't need to do anything with it. I will most likely however glue up a lam just to be on the safe side, but its still very heavy for its draw length. which is about 12 inches, maybe 14. Id rather be on the safe side of course, but just thinking here, make sure to shoot down that kind of thinking if its no good. or reaffirm it if its good to think that way.
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Nope. Just a lam to cover the static part of the tips. Way easier than a complete belly lam. Look, it may not be worth the effort to some, but it's your baby. What I described is really pretty simple and it saved a bow for me. Take it hunting every year!
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Agreed. Belly lam the last few inches should do the trick.
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In case you decide to try it, here is a picture of what I did. Granted you have some humps and hoop-d-doos to deal with, but I would sand it flat (on the belly) or at least flattish, and feather it in.
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sounds good, thats what ill do!
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If you are going to put any recurve in the tips, heat and bend before you glue the lam on. I don't know what you are going for in terms of design, nor do I know what kind of experience you have, so I'm just making sure you've thought about it. Few thoughts, don't bend the bow until you get the hinge fixed. What kind of tool are you using to take wood off? Looks like a rasp??? Too aggressive at this stage. Use a draw knife if you have one. A nice sharp knife of any kind will suffice otherwise (6, 8, 10 inch blade). Take little paper thin slices off (holding the blade at a 90 degree angle to the wood and scraping) as opposed to big chunks. If you use the rasp, I would stay with the flat side. Your wanting to get the belly board flat from handle to tip. Worry about following the contours once you have it closer to finished.
***Don't get it too thin in ANY spot. If in doubt, leave it thick and move up the limb.
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now to be clear. i remove a 1-2 inches of wood around the hinge area so that its flat so i can glue up a lam correct? i will go get epoxy if that's whats strongly suggested. if not i will use something like tb2. I have never done this before, however, it seems strait forward enough. Let me know what glue and if i should remove wood.
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Well, the last 6 inches or so should be static, so feather the lam out just short of that 6 inch mark. You don't want the lam to have to bend. The bend will end where the lam begins (close). So there-in lies the answer to your question. 1 to 2 inches seems to short. I would make the lam 4 -5 inches long, so the flattened area on the belly should be 4 to 5 inches as well. Something to consider. If the limb is too thick where the lam begins (handle side) you will have hell with it. Get the thickness close to where you want it before you glue up. You can always scrape some of the lam and glue off if you need, but get it close tiller wise.
I think any good glue will work. Your not asking the joint to bend, but use good gluing technique. TB, epoxy, hide glue, knox gelatin, carpenters glue. Any of these should work if applied properly.
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so even with a REALLY short bow i can still make 6 inches of tips static? if so i will need to apply another lam to the other side to make sure that the othe side doesnt bend as well...
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I have no experience with vine maple. I don't know if 60 inches is long enough for the species. You do need to keep the last 6 inches or so stiff to keep it from stacking on you regardless. Go 4 inches if your concerned about it. Might want to back it with raw hide just to make sure. Hey, it's just an experiment at this point, but I think it will work.
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ok, so im wondering then, is rawhide as good as flax at keeping it from failing? i was reading the tbb1 and i read that flax can make a bow last even if it wants to break it cant.
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I've never used flax. Rawhide will do the trick. You have to get it tillered right first.
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yeah, so where can i get this rawhide? i will be putting the lams on tomorrow, and if necessary getting some epoxy.
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This forums trading post. You can also buy a rawhide chew toy. Soak it to soften it up.
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ok, so basiclly any form of rawhide will work so long as i make it soft?
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Pretty much. I like the thinner stuff, goat or deer. You may not need it. Maybe someone with some experience with Vine Maple will chime in and answer that question.
You asked if you need to do the other side as well. I did. I wanted the bow balanced, so I duplicated the stiffener or lam on both sides. You'll have to make that call.
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I have to disagree with slimbob's advice- if you make both tips static by gluing on belly lams, you will have less working limb which will make it harder to get your 29+ drawlength. Static tips would reduce stack a little, but in my opinion any short bow will feel like it's stacking- it's just physics.
also these lams will prevent your plan to flip the tips- heat will kill the glue.
my advice is to tiller out the hinge and just accept whatever weight it comes out at.
What is the thickness at the hinge? My 50 lb bows are only about 3/8 thick 5 inches from the tip.
how did the hinge develop? What tool were you removing wood with? were you using a caliper to measure and compare thickness? When i tiller lumpy VM i check the taper with a caliper often. I tiller with a rasp and follow the lumps in the back from the very start. if you dont follow the lumps, each one becomes a stiff spot, reducing your working limb.
you can use a crescent wrench like a caliper, or even carefully measure with a ruler. In my opinion a caliper is the #1 tool for achieving good tiller in VM. Using this tool to create an even taper results in an evenly bending stave at first low brace. I have been working VM for over 15 years.
have you tried drawing the lines on the sides to judge bend as i suggested earlier?
beware of the drawknifeit can easily tear up splinters on this type of wiggly grain.
caliper, rasp, caliper , rasp, caliper raspcaliperraspcaliperrasp. repeat.
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Aaron,
Interesting I have been working vine maple for 20 yrs, never used a caliper once. I suspect it could be helpfull, but really over thinking it in my opinion. You could add a belly lam, but a lot of work with iffy results. I would get a new piece of wood myself. To the guy thats building this bow....STOP trying to follow the dips any more than is needed for a rough tiller....then go back, and remove wood from the dips, yes you may need to remove wood from some of the dips prior to your final tiller. You also have to factor in natural reflex (if this is a factor) top, and bottom limb can have slight reflex, while the bottom straight to slight deflex. I can't see how calipers can help at this junction??? I have built well over a hundred vine maple bows.
VMB
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the thickness at the hinge is 5/16 of an inch thick and its 3-3 1/2 inches from the tip. as ive said before, there would have been a LOT of near-handle and mid limb wood removal to get it to 50 lbs at 29 inches. thus it could be that ive removed all the wood nececarry from that part and just have to remove all over the rest of the bow. for all i know it could be that since it is shorter and since the limbs will be thin anyways(currently they tapper from the handle 1" to pretty close to 1/2" near the hinge.) Let me know what you think. When i was pulling it at low brace it was reading 45 lbs at 12-15 inches.
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vinemaple bows- yeah, the caliper is not the only way to do these, just my favorite way. The caliper is just my way of checking what you probably do with just eyes and hands. I respect your opinions and ways- you seem to know what you're talking about .
ionic muffin- if you have 5/16 at the hinge, then you might just get it tillered out . as you say here " thus it could be that ive removed all the wood nececarry from that part and just have to remove all over the rest of the bow. for all i know it could be that since it is shorter and since the limbs will be thin anyways"
I have a bow about like the profile and length you have there, but it's at work. what is your width at handle and at fades? how wide at the hinge?
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3/4 inch wide at the hinge. Fades are 1 3/8 inch wide, and handle is 1 inch wide.
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To clarify...If you can tiller the hinge out yes, tiller it out. You never had a problem to start with. I offered up a solution to a problem...a hinged limb 2-3 inches from the tip, assuming it can't be tillered out without dropping the weight to an unacceptably low number. As to the tiller profile, you got 2 options with with the end of a bow limb, bendy or stiff. If bendy, it will be wide, flat and heavy which will rob from the bows cast. The problem will be compounded by the whip tiller which will shorten the bow at full draw, increase the string angle and add stack weight, further diminishing cast. If stiff, your tips will be lighter if done correctly, increasing the bows efficiency. It will be effectively longer and it will have a lower string angle, decreasing stack weight. All of these are are advantageous qualities. The only question in my mind then, is can you design a bow, made from VM, 60 inches in length, with stiff outer limbs? I don't know! I stated earlier, I have no experience with VM other than second hand info. It is supposed to be very strong in tension, very elastic and an SG over 60. My opinion, stiff outer limbs should not be a problem at 60 inches. I have made countless bows with stiff handles from 48" to 54" range. Some from lesser wood than VM, and all with stiff outer limbs of some percentage. The call is yours muffin man. I simply offer a way to resurrect that stave if it's needed.
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alright, thank you for all your advice. i think that i will see if this stave can be further reduced before i make any drastic mesures like lam and backing it with rawhide. if it does turn out to be a problem and a perm hinge then i will go with some lams, otherwise wish me luck :)
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well, its over :'( she snapped near that hinge after all the reducing i did :'( oh well, if nothing else i could try for a 15-20 lb kid bow from the left overs.
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Sorry man. Doubt it will be the last one you break, if you keep at it. Think about what went wrong and use that info on the next. Good luck.
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yes, i learned more than i thought. now more than ever i will go ever so slow to make sure i do it right.
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bummer- better luck next time!
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I have a sneaking suspension that the bow failed because the MC was too high. I didn't think much of it at first, but the stave had 4 inches of reflex before i started tillering, then all of the sudden it had 1inch. I guess i should have see that as a sign that it was still not dry enough.
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I think it is a mistake to blame the MC for the break. High MC will cause the bow to take a lot of set but it wont make it break. It is common for vine maple bows to start with alot of natural reflex and have much of it pullout during tillering. That's not to say that your wood wasn't too wet or that your design wasn't overstressed but I don't think that's what caused it to hinge and break. I think the clear culprit was a spot that was too thin which caused the hinge and the break. I had nearly the exact same thing happen to me on the only vinemaple bow that I tried to make and I think it was for exactly the same reason. I was getting to aggresive on the dips and wasn't paying enough attention to the overall taper. I think Vinemaplebows has the right advice. He's not saying to ignore the bumps on the back forever only to leave them thick to start with and gently reduce them down to get them working after the bow is braced. If I had done that I probably wouldn't have broken my bow. Vine maple is a little trickier than it first appears between the reflex and the rollercoaster bumps it has some challenges for newer bowyers.
Here's the link to my blown vine maple bow. http://www.primitivearcher.com/smf/index.php/topic,26421.0.html
Good luck on your next one. :)
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Thanks for that, it looks like a similar problem. I am getting some hickory soon, and i hear that it can take a TON of abuse before it breaks. The only problem i've been reading about is that if you live in a high humidity area you may be prone to having higher MC and since i live in Washington i think that it may be a small problem.
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It is a consideration. I live in Western Oregon so it's the same deal. I have a hickory bow that has been fine BUT I don't shoot it in the winter when it is damp. So it is a good dry weather back-up bow but I wouldn't consider it for your primary/only all year shooter. If you can keep it somewhere consistently dry inside then it should theoretically be fine. In the time it takes to go out for a day shooting it's not going to take in much moisture with a good finish. It takes day/weeks to significantly change the MC in a sealed bow. But making sure it wasn't soaking up moisture in the house would be the trick. You should give hazelnut a try. it dries as fast as vinemaple but it doesn't have as many tillering challenges. Another good local wood is oceanspray (ironwood). it takes longer to dry (a year or so) and has a tendency to check but it makes a sweet bow. And don't give up on vine maple, it's a really solid bow wood it just has some quirks that we have to figure out.
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I think i will step back from vine maple till i have a few more stave bows under my belt.
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the other thing, you mentioned wood, funny that i only have Black locust and plumb on my property. Other than that ive never seen ironwood, oceanspray, dogwood, ect
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To bad ,but could see it coming,I doubt MC had anything to do with the break,set yes but if the MC was to high it probably kept it from breaking sooner. :)
Pappy