Primitive Archer
Main Discussion Area => Bows => Topic started by: Limbwalker on February 16, 2017, 05:17:03 pm
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Good afternoon,
I have a number of good staves and a few that have bad cracks or some kind of defect. Last night I decided to make a bow from various scrap woods and it has snowballed. I'm quite sure there is a great chance I've committed some rookie errors and I was hoping, perhaps if anyone has any ideas or can increase the functionality of this possible bow, I would much appreciate it, I'm all ears. I have successfully made 6 bows so far and they're still in one piece. Though they generally came in #35~#45. I've broken a few as well and I like it. (The process more than the breaking)
I will as clearly & quickly as I can fill in where I'm at now with the bow. If anyone has any interest I will keep posting progress & pictures until it's either a bow or scrap scap wood.
It started with this, a billet of old old Osage, a billet of Mulberry and a piece of Black Locust for the handle. A double splice with two simple V splices into the BL. The BL was thinned to 5/8" and the splices are 2" deep into the BL. The idea was to put a bamboo back on and build up the handle with Osage and BL; which would effectively sandwich the double spliced limbs. I then decided to make the Osage, Mulberry, BL splice the core and add a Juniper (ERC) belly. I had a roughed out Juniper stave with a nasty crack in one limb. I cut ~31" off and split that giveing me two pieces of Juniper for the belly laminates. At this point the bow is a projected tri-lam. This means the core needed to be really thinned down, so I did.
I have never made a bow from boards. I have nothing against boards, I just prefer staves and harvesting my own wood. I really like hand tools as well. I make laminates by first splitting off the part I want, next use my hatchet to thin in anywhere from 1/4" - 1/2" depending on the need. If it might break with the hatchet I clamp it to a 2*4 and keep on with the hatchet. Once close, I clamp it to my flat 2*4 form and rasp with two hands to keep the rasp flat. I use a marker/pencil to make lines in order to see when they disappear evenly. Once I'm almost where I want I switch to my knife and with two hands scrape it smooth and close in on the final flatness. It works well for me and this is the most effective system I've yet to use for making lams with hand tools. Well with the Juniper belly, it came out a bit thin for a belly. ~1/4" leaving me not much room to tiller. And I thought too thin for the power of Boo and the Osage/Mulberry limbs. So I found a messed up BL stave split it as if 1/4 sawn and decided to make very thin lams out of that. ~1/16" - 1/8". I have one done as of right now. I made the BL lams to attach to the Juniper. This will make the belly BL/Juniper. The idea is the thin BL will aid in relieving some of the compression on the Juniper yet still allow the Juniper to preform. I like springy yet slightly stiff BL lams in this position. Also I tapered the core too much I fear. It goes 3/16" - knifes edge. I think the BL with buffer both Belly & core. I might take core down to 1/8", not sure yet.
I am going to put up pics of above to give anyone a better idea of this fun mess I got going on. The BL laminates still don't really give me more tillering room, so I feel like I will hit or miss right out of the gate. I am going to glue up the belly lams first, then add that to the core and finally the Bamboo back. To me it has to be close after glue up. If I don't get this in that small window I think it will fail miserably. I still have not decided on a profile. I was thinking taper the core and back and leave the belly as is. Which will be Juniper 1/4" straight across and BL glued above it 1/8" - 1/16". I'm going to complete this, I feel like I am taking a shot in the dark, but I do know very well the woods I chose helps, but I might be wrong there too. Oh, 62" end to end. If I get to cut string grooves and add a riser, that would be terrific. I'm all ears and if you read all that thanks. Here on out I won't need to explain so much. Alright I'm gonna put up pics,
Cheers,
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Hmm, apparently even one photo is too large of a file. I am on my iPad here and my photos are on it. I apologise, let me try to figure this out real quick. I will get them up though. Thanks.
I don't have a computer right now so I had to get an app to compress photos, quality suffers, but it will hav to do at the moment.
The second pic I'm not quite finished slimming the BL part. It is to give an idea just by holding them together.
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You have my attention, sir.
I all the time used to splice billets at the handle, flatten the back with my power hand planer, and back that with bamboo or hickory. Never have done two splices, and I'm very interested to watch you work out one mullberry and one osage limb.
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Ok cool, I will update this project then. I'm winging it and just going to try to do the best I can. The Osage is questionable and I'm very curious to see how well it does in the core position. It came from a dead log. It doesn't look like Osage. Lost its color. I got that piece and a walking stick out of the 7.5" * 6'log. I did a test sample and it bent well and far. It's real hard and springy. The surrounding wood was littered with bore tunnels and dead dead. I hit it with a hatchet and it would blast shrapnel everywhere. The limb I got, though on the verge, still peeled and was heavy. That's part of why I thought it might do well in a core. I might get some work done tonight after my daughter goes to sleep which is about now. If not tonight I will definitely make progress on it tomorrow.
Open to suggestions too, I like creative ideas from others. Anyway I looked at the core and I did not taper to a knifes edge, thankfully it's sitting at 1/16" hope that is ok. Yeah everything except the bamboo & riser will be spliced. Never done this either. Have good one Springbuck and talk to you soon.
This is the dead Osage log where the one limb is from,
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I'm calling it a night, I hope to tackle roughing out all the laminates for the Osage limb tomorrow. Here are the dimensions after roughing out the Mulberry limb. Lastly I failed to mention, the fades are 1 1/2" and tips are 5/8" wide. After glue up the final dims should be fades 1 1/4" tips 3/8" or 5/16". Does this sound right? Maybe I will glue in some sort of R/D. I might steam bend some sort of recurves into Juniper, BL and heat bend Osage and Mulberry and finish recuses during glueing, in order to store energy from glue up. Maybe 2" of perry reflex and see if it comes straight. All that I will decide later. Goal ~61" n/t/n, 1 1/4"~1 1/8" Fades and 3/8"~5/16" Tips. Shooting for #55 which I've yet to hit on completing a bow. I'm still learning about archery, my draw length is 28" maybe little more, but I've been anchoring at ~27". An archery instructor at a local range initially measured my draw length and that is what he said. I feel more consistent right now at 27" so I will tiller to 27"-28" I might be way off, does this plan look/sound reasonable with this bow? Looking at the tip pic going to thin BL a bit more, I think.
One mistake I know so far is the grain on Juniper. I failed to even think about it. It's just the way it would be as on the bottom of a self bow. Does that make any sense? Can anyone hazard a guess as to how detrimental this mistake is? If it's real bad I have one more scrap I can chop slim thin.
The pics do not have the backing on which would add 1/8" to fades and 1/16" to tips. Finally I left the BL lam a bit thicker on Mulberry side to counter the stronger Osage side which will have slightly thinner BL lam. And the Juniper was left with more meat on tips.
One more last decision. Do I stick with Bamboo back or should I do a one piece Black Locust back? I can do either. A part of me wants both. In the spirit of the bow the BL back sounds slightly more intriguing to me. Anyone want to weigh in? I will go either way if there is any interesting in one or the other. Well until next time, goodnight.
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Pulling a backing out of a stave is kind of a trick. I'd go with bamboo.
I've made elm backings by taking a straight sapling too short to make a bow, say 3-4" diameter, slicing off a slab on both sides with a chainsaw. Like, plunge cutting while the little tree stands, and sawing down each side, then cutting them free. This good for elm, because young trees usually have a slightly spiraled line of pin knots down two opposing sides, leaving two crowned, knotless surfaces 90 degrees to those. It's a pain, though. The natural crowned front makes it hard to machine flat, and I have to clamp the tobacco juice out of them to get them dried straight and flat, AND sometimes I still have to shim and work around little humps, AND I still have to plane, sand and rasp them to consistent thickness. I had no better luck doing it with my bandsaw.
The reason I told you that is in case you plan on doing the BL back. I think your planned dimensions are fine, but if you start too thick you'll lose your belly.
So, even though your juniper is pretty thin, juniper is good stuff, and your "stack" is already pretty thick. Most of the compression force is felt at the surface of the belly, and i make finished bows all the time with less than 1/4" thick belly lam. I don't think you would be helping the ERC with a 1/8" locust lam, maybe hurting it. BL is STIFFER than ERC, but not as ELASTIC, so I think you'd just be putting the locust in danger of fretting.
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" The idea was to put a bamboo back on and build up the handle with Osage and BL; which would effectively sandwich the double spliced limbs."
A power lam should handle this, but if you have enough thickness, it may not be needed. splices atre pretty strong. Guys on here splice stiff recurves on all the time, both plain and under a backing.
You did right to thin the osage an mulberry, but since they are the core or middle lams now, they will be 90% loafing. Concentrate on good glue lines, protecting the splices with stiffening, and a decent backing.
Bamboo can be amazingly thin as a backing and be effective, as long as you have not flattened or gouged the back or nodes, and if it's consistent. With almost all woods, I trap to a bamboo back.
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Thank you springbuck,
Really helpful answers to my questions. So on average your saying I'm already pushing too thick? I always wondered how deep the compression forces run into the belly wood. The Mulberry feels a bit floppy at the current thinness. Would a thin layer of something help with that in terms of spring back, to reduce set? Compression forces are mainly on the surface is good info, I thought it crept around the sides and up toward the middle. I'm assuming the compression congregates in the handle region when the bow is drawn?
No I don't grind any nodes or decrown any bamboo. I only remove the rind and carefully get the bamboo back smooth to avoid those little splinters. When you say trap to the bamboo back do you mean the bamboo doesn't run along the edges of the wood? Meaning bevelling the wood a little to meet a strip of bamboo running down the back? Or trap the belly? If you can expand on that, that would be great. Again, really appreciate your time and thoughts. I will revise my bow plan per your great advice.
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One more thing to consider, this is the piece of BL I was thinking about for the back. If you can take a look, I took a couple photos and if the grain doesn't show up I will take another layer when I get home. I'm going to split a bamboo piece off for the back. I can walk outside and cut bamboo, I virtually have unlimited amounts of it. I get about 3.5" diameter pieces of bamboo which I can stretch to 1.5 or little more for a backing.
I'm not disagreeing with you at all, and please keep the thoughts coming. If you can take a look at the BL back I split yesterday and tell me what you see. You know what I do for work, so I have a stash of BL, covered, two years old for fire wood, which I give to family/friends. When I started making bows I hit up my stash and got a few real nice staves, no knots or twist. They have been in my basement for four months and are ready to become bows. Anyway I didn't just try to split a backing piece and cross my fingers, I scored the split all the way down and stayed ahead while splitting it to make sure it left a straight grained 3/8" thick slab. Take a look.
Springbuck I will show you th bamboo too, I have some dried poles. I am going to process that and I will post a picture. If you still have a bad feeling about a BL back, I will hold off on processing the pic below.
If I, and probably will, use bamboo like Springbuck suggested, I think I understand trapping to the bamboo, I understand trapping. See what I can find out. Thank you sir
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Sounds to me like the mighty knight who arrived on his white charger to save the day, and promptly rode off in all directions at once.
You have changed course so many times I can't imagine how you can remember what the effects of those changes might be.
You certainly are willing to put in a lot of work making those laminations with hand tools. Unbelievable.
For future reference, you can save a lot of guess work by making a pyramid design, which does not need to taper in thickness. Each lamination can be the same thickness end to end.
As for juniper, though I have never used it but have only heard of it's being good with a sinew backing--the sinew storing the energy.
Guess you are really honing your hatchet skill, at least.
Jim Davis
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Hey man, I understand this whole thing looks like a ten car pile up. The idea is to try and use otherwise scrap pieces to make a bow. Except the backing. I think I was just worried the bow would be too light and/or the bamboo too strong, but I really don't know till I try. I'm not going to use the locust pieces, like Springbuck said. I will just have to tiller it accordingly. It doesn't take too terribly long to make the laminates. Prepping the split and reducing them with the hatchet really makes them go pretty quick, unless I screw up and have to start over, which may happen :)
I guess I had things backward in my mind when I was thinking of a two piece belly with a thin stiffer portion above the Juniper, but you guys have the experience, which means you have the knowledge, I don't.
So where I'm at now is this. I got the core all done and set aside. I asked about the grain orientation on the belly, because I felt like I made a big mistake by not paying attention to that. So I made new Juniper belly pieces from my last Juniper scrap and I like them much better. They are only a tad thicker in the mid limb and thinner toward the tips. No more Juniper scraps so they are it. I just need to double check the glue lines and consistency to finalise them. Probability tomorrow.
After that there is the back to finish. Only if I get the BL near perfect, I will use it. Any second guesses I will go with very thin bamboo back. I have a lot off bamboo and kind want to do something different, that's really why and to satisfy me curiosity.
After I have the back done, I'll do several more dry runs and finalise the profile, glue, add riser and that's it.
Nothing too different tonight. Springbuck tomorrow I will post how the Juniper and the core go together. If you see something you can tell me, if you want. Asharrow I think the Juniper will hold up as long as I get things distributed right. We will find out how I do on all that soon enough. I'm not in a rush to glue it up and I am taking time with glue lines and back. Good to know about the pyramid design, makes sense. I guess it's an efficient design. I don't dislike the look of them, but I kinda dislike the way they look. I know, not a good reason probably. I'm going to try for maximum efficiency on however this design ends when all is said and done. I surely do not want to overbuild. I worry about that a lot and really don't like over building, I have a hunch, that is why all my bows have come back too light so far. It's only my preference, I'm not being critical at all.
My goal is to understand the bow and all of its energy, might take the rest of my life? I want my bows to work, every part to be there for a purpose and not have extra wood hanging on gumming up the works. Reading here has answered many questions I have had and I'm grateful for that, I feel though that doing is the only way I will truly learn anything. People operate differently and I like that. There is so much to learn about bows I just have to make my mistakes and keep trying. I posted this project hoping to learn more than if I just did it, and I have. Thanks for that.
One of these days I might get it right. I will try not to ramble, I will wrap this project up soon. In real life I don't talk, introverted and I think, I can see a lot of what I write is taken the wrong way, I will work on that, it's hard to gauge a voice through writing alone, I also write fast simply because I have limited time. I try to come back and edit spelling sometimes, no time to proof read unfortunately. Thanks for the comments, Until next time,
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I admire your energy and drive :) Keep it up!
When making a laminate bow it is always advisable to use the best materials possible.
Backs can be made from any tension strong wood but some are more suitable than others, generally woods with interlocking grain are used, hickory being the prime example. This will allow you to use a piece with a little grain violation. The most commonly used woods for backings are hickory,ash,maple,elm. Of course bamboo works as well but not all bamboo, moso and Tonkin are commonly used.
A core wood should be not too heavy s,g,, glues well, diffuse porous (so it stands up to sheer forces well) and easy to work. Maple is the core wood but many others will work.
Belly woods need to be elastic and compression strong. Osage, ipe, pau amerillo are my favourites but again many others will work.
The outer most surfaces are what do all the work. Maybe only the outer 1/16th. So your two piece belly isn't a two piece belly! It is another core. The core basically only keeps the back and belly the correct distance apart for your draw weight.
As for your combo. I would have gone with a boo back, juniper core and osage belly.
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Thanks mikekeswick for taking time to say all that. It helped clear up a couple things for me. I got rid of the two piece belly idea per Springbucks' suggestion. it will be Juniper. The osage is too far gone I think to handle compression, but I think it will handle being the core. I say this not because I think I know about bows, I'm not a bowyer at all, you are. I've made a few bows and always played it safe with typical combinations and I will continue that. This bow is scrap wood and I'm not gonna play it safe :) Forcing myself to use only scrap pieces limits my options on purpose. If I wanted to I could use a nice piece of Osage for the belly and a cherry core backed with bamboo or hickory, maybe next time. I don't know why I do this but, it doesn't stress me out at all and I enjoy the puzzle.
The reason I might use BL for the back is to kind see how it works or doesn't work. I haven't found much info on it, except I found a little thread. The guys with experience thought it could work. I had made a quarter sawn lamination and in the thread someone (can't recall screen name) with tons of knowledge thought plain sawn would be better for a BL back. Indeed I think he was right. I made two 1/8" samples of each and the quarter sawn piece broke plain sawn did not. I was very impressed with the PS piece. It had ~25% more tension than the other as well. If anyone wants to see the test, take a look.
The QS piece broke just before the point you see the other bending. No didn't tiller my samples :)
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Thing is, if an experiment is to result in new knowledge or confirm a hypothesis, it is necessary to change ONE variable ONLY. You seem to have several unknown's in your formula and won't be certain why the bow breaks if it does--did hidden compression failure cause a tension failure? Did the core fail in shear? was there a hidden weakness in the back?????
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"Really helpful answers to my questions." No problem, this is exactly how I started out! Intimidated by staves and ring chasing, I started with bamboo backed bamboo flooring bows. I had no tools. I remember rubbing down my first bamboo backing from 3/8" to 1/8" thick from Three Rivers on a long, flat board with a 40 grit sander belt, glued to it. Took HOURS.
"So on average your saying I'm already pushing too thick?" I don't know exactly, but I quickly learned while making laminated bows that I was starting way too thick on most of them. A 68-70" R/D bow with 12" fade to fade ends up less than 1/2" thick and from 1-3/8" to 2" wide with most woods like ipe, osage, BLocust, massaranduba, brazilwood, etc... ERcedar, yew, and juniper might be thicker. They are lighter, less strong, less stiff, but as, or more, elastic.
"I always wondered how deep the compression forces run into the belly wood." Generally, deeper than the tension forces do, but in (very) broad terms, the first 10% of thickness on the back, and 20% on the belly do almost all the work. The rest is feeling only a fraction of the strain.
"The Mulberry feels a bit floppy at the current thinness." Floppy, thin lams don't "fight the form" But a thin backing can hold a lot of stress from a thick belly., if it's sound.
"I thought it crept around the sides and up toward the middle. I'm assuming the compression congregates in the handle region when the bow is drawn?" Middle of the bow feels the highest forces total. I don't understand the other part.
Trapping: Yes, I mean the bamboo is skinnier on the back, than the core is on the belly. Narrowing the belly is reverse trapping.
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I think you COULD use locust for a backing. A perfect quartersawn-style clean-faced split would be the exactone to use, too. My thinking is that thin BL belly/boo back, the locust is unnecessary, unhelpful, and too thin. BL as a backing is a sketchy unknown, too thick, and too heavy. EITHER of those start to add up to a very thick stack.
Heck, looking at that BL, split-off pic, I'd say clamp that straight smooth it and find a backing for it!!
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Ok, couple of criticisms just to keep it on the rails for next time! ;D
Yes, the BL QS backing was doomed. I could tell you by looking it wouldn't hold because of those dark lines where knots wiggled the grain.
Juniper is different than the STRONG woods Asharrow mentioned. ERC and juniper is ELASTIC, not bend resistant, in compression. However, I looked at your juniper belly slat a bit closer, and I'm not entirely convinced of its grain structure.
Yes, osage and mulberry are both heavy and slightly underutilized as core woods. No big. But, thin slat of softer wood (juniper) on the belly, with mediocre grain might be too much for the belly. Keep this core thin and belly lam thicker.
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Springbuck now we're getting somewhere, thanks so much for the no bs answers. For the record when I talk about what I 'think' or 'thought', I m not necessarily disagreeing with you, I am thinking about if someone is just starting out, five years from now, and reads this, that they get they're answers. Make sense. Just discussing ideas and experiences is helpful. Then you come in from behind and one by one, knock the questions out. Thanks. I'm regrouping and I will show you the new stack and you can tell me what you think, I did get rid of the whole double belly a while ago, thanks to you. :) I have a feeling Asharrow is smart. You see I didn't go to school, I paid my dues in other ways.
Asharrow, I hear you, I do. I admit my scientific process is no process at all. Been winging it from the jump. Your right. How will I know who the culprit is if it breaks? For a while I was kinda talking to myself here, until people chimed in, so I was working it out. My mind has changed since the beginning. I tossed an idea out about the double belly thing and it was shot down more than once, I'm over the idea, it's dead.
So should I be building two bows at once with one being the control? Joking, you don't want twice as many questions do you? lol. I have learned a lot so far and if stopped now it would have had value for me. I'm not going to stop obviously, but that's why I'm messing with the BL and doing samples. I know I need to do muipule samples to get a real accurate average. Not enough time.
Mikekeswike said it's important to use a backing with interlocking grain. Here is a thread about BL back https://www.primitivearcher.com/smf/index.php/topic,29125.0/nowap.html Since BL does not have interlocking grain, I'm concluding this is why it is better plain sawn.
The bow is a trilam, that will not change, done, backing undecided, I made new bellies with better grain and am processing a bamboo and a BL back and will decide soon. I just have to get e glue lines and triple check the thickness on the sides of belly lams; I don't want any twist now. When I complete that, I will post a pic, you and Springbuck can tell me what you think if you want. Anybody for that matter. Quick question, two Knots on one belly lam, issue? Not on the edge and I very well might work right past them.
So I have the core and Belly established. I would like to glue them up first. Then glue the back on that last. Because I may want to add reflex/deflex or just flip the tips w/steam/heat to the core and Belly first and then try to store more energy by tightening it all up with the back. I do like to keep my options open. I produce the best results not being tied to plan and then missing an opportunity because I was hell bent on a plan.
In closing I feel like the core and Belly kind of already have been proven to be sufficient in the past. Adding a BL back would be stepping more into the unknown for me. Oh the splices, I have learned a ton so far about that too. I feel like if a splice fails it would be quite obvious. Ashjim, your saying if the back fails I won't be able to distinguish because they may all break and which one went first kind of deal?
I appreciate all the thoughtful responses and helpful tips/answers. I do not want to rush this next bit, but I do want to put the poor thing out of it's misery as well. Soon enough. Well, good evening and please, ideas; thoughts
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I decided on the back and it will be Bamboo. I have a couple other staves I feel will be fun experimenting with a BL backing. I have a white oak stave that had checked all along the back so I had to violate the back of it to remove the checks. So I with be doing a plain sawn BL backing on that another time.
I haven't had time to work on bows the past few days, but tonight is free and I'm going to be getting things in order. This bow should be glued up by the end of this week. Thanks for all the helpful advice so far.
Springbuck, I'm going to do exactly as you said and trap to the bamboo. I will post pics of a dry run as soon as I touch up glue lines and finish processing the bamboo. Any additional advice for the bamboo? Before I narrow it to dimension and thin it?
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Update, I am finishing up the Juniper belly laminates. I decided I'm going to have the tips flipped and some deflex off the riser, which will be done when glueing up.
One of the Juniper belly pieces cooling off, dry heat bent.
The tips will be static, so after things are glued up and the bow is shaped the tips are going to be as narrow as I can get them and not bend. I have already prepared underplays if they are needed. If I can get away without them, I will.
Another thing that changed is the core is now 5 pices spliced together. My daughter 11 was messing around with it and she broke 4" off of the Mulberry tip. She said she was bending it, I certainly was not mad, it became a good opportunity to let her learn a bit about wood. Now she wants to make her own bow. She picked one of my Osage staves of course. I gave her a yard stick & pencil, lets see what she comes up with :)
Anyway, I have another much better old old Osage log that I have split up and found some scraps from it and made a new tip on the Mulberry side and did the same on the other side to match. In the end, that hard Osage will aid in keeping the tips static so oppritunity lies in every little "accident"
Be well, until next time.
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can someone help me out real quick? How much does the wood variety matter in the power lam? I can use Osage, BL, Mulberry, Juniper, Hickory or Ash.
I'm going to go with BL unless that is a bad idea, thanks
Never mind on that one, I know what will work just thought of it.
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About any wood will work between the belly and back. hardly any energy storage there. Lighter is better, since that layer is just along for the ride. "Power lam" is just a hype term, probably originated in some sales department.
Jim
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Thanks Jim, that frees me up to pick something pretty much based on color alone. My main concern was stiffness to thickness ratio and if a stiffer wood was better, but after research what I read is congruent with the above answer. I do need one because the belly wont be thick enough to start the fade into the riser. Thinking about the function of the PL, I would think as long as it's not incredibly brittle anything will do.
I have a about a century old scrap piece of Osage that will slightly accent the bow, thanks again Jim
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Its not a hype word derived in an office, Jim. They use the term "power" because it is meant to stiffen up and strengthen only a certain section of the bow.
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I wanted to double check something, I've used bamboo before and from my understanding, after the rind is removed it is a tan color, correct?
I don't want to harm the good fibers; it can get concerning because I'm noticing two color changes as I remove the rind. I suppose leaving the rind on is an option, but I would like it gone on this bow. I put bamboo on an Ash bow before, but I think I didn't get the rind all the way off in that one. I gave it away so I can't remember. Doe my question make sense? I have searched the web and read contradicting things. Anyone with experience please feel free to let me know, thanks
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Almost
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I glued up the belly and core. I planned on that for reasons I said days ago. I'm glad I did it this way so far because it gives me a chance to better tune the profile. Since I'm working with laminates I made from scraps, they are not the same. I will sort of floor tiller it before I put the bamboo on. That's the best way I can describe the next step. Basically I'm going to get each limb closer to final before I put the back on, but not too much, just a couple spots. I have knots to deal with on belly so it's been a process this far.
I will have pictures soon and after the bamboo goes on, I will do the final tiller and that's that. The final tiller will take time, I'm not in a rush. Juniper can't be rushed. It took time and convincing to heat bend the Juniper, but with patience I was able to do it and it will be the same drawing the bow.
I am going to temper the bamboo. Wait I shouldn't temper the bamboo if it's the back. I'm going to do it and I will tell you why. There is a report done by for bamboo rod makers about this subject. Rod makers have to deal with elasticity and set as well. After years of testing a report was finally made and if done correctly, tempering at no more than 200C (392F) increases MOE by about 2-4% but increases resistance to set by a much higher percent. Also there are some good tips in there about water reduction in the bamboo, things I never paid attention to. I'm going to be sure to seal the ends of it immediately after tempering it. The article is 30 pages and if you use bamboo and can get through the article, read it. I will leave it for anyone to read. There is good info in here https://www.dropbox.com/s/edxnj4ujc0qdtnz/Bamboo%20in%20the%20Laboratory.pdf?dl=0
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Here is a pic gluing up the belly and core, I added a few wedges after I took this pic. 8 pieces of wood so far. I did this two days ago, glue lines came out very well. I will add pics when I glue the back on maybe later today. Note this is not the final profile of the bow. Working my way there.
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Its not a hype word derived in an office, Jim. They use the term "power" because it is meant to stiffen up and strengthen only a certain section of the bow.
But it only stiffens the section by making it thicker. Internal layers add almost nothing to stiffness by virtue of the material used. That's why some bows can be and are made with foam cores. The foam just adds thickness. So one kind of core material or internal lamination can really only be better than another if it is lighter. Not be cause it's some proprietary material.
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Power lams aren't in limbs, they are situated in the handle and fade section only to stiffen it up, or "power" it up, if you will.. Foam would do no good in a riser as a power lam. Works great in a limb as a core.
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But as I said, they only stiffen it because they thicken it. It's just a cute way of saying the material makes the handle thicker.
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But as I said, they only stiffen it because they thicken it. It's just a cute way of saying the material makes the handle thicker.
Much like trolling is a cute way of saying contentious. ;)
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Ok, then you come up with a less flashy name that you approve of, let me know what it is and I will start using it instead of power lamination. I kind of like "material that just makes the handle thicker" better than "power lam". But that's just my opinion.
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How about just saying add a lamination (even lam if you like) to thicken the riser?
Doesn't matter, I'm just practicing my curmudgeonlyness. Guess I'm getting good enough at it to go professional. :(
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Here is a picture of the fade/lower limb area; I added the SFP lam, I used a scrap piece of really old Osage. The Bamboo will most likely be put on tomorrow. Nothing is sanded or in its final shape, only rasped, and more rasping to do. The bow will be completed fairly soon, I hope, I have a couple others I'm working on too. I still have used only hand tools and wood from my junk pile. Taking my time and having fun with it.
Forgot to say, the riser section is more like a self bow design and there will be no arrow shelf, the bow is relatively short, (The handle goes on after Boo) I like thinner deeper handles anyway and the profile is working out for really nice arrow placement.
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How about just saying add a lamination (even lam if you like) to thicken the riser.
This is for neither Pearl, or Asharrow, who both know what they are talking about. :laugh: But for anybody else........
The term came about maybe 18 years ago or so over on Stickbow.com/Leatherwall, along with "flipped tips" and the term "boofloo" to designate bamboo flooring, etc....somebody used it and it stuck. It doessn't really add power, and I'd make one out of any wood I had handy that would make an kind of bow.. So, not pine, but definitely walnut, hickory, elm, etc....
Specifically, it has been used to refer to a shortened, tapered-out lamInation between backing and core, or between laminations, as opposed to an extra lamination just added to the belly under a riser block or stack.
It was found back then that if you glued a 1/8" backing to a 3/8" belly lam, that was plenty for the limbs, but if you glued on a handle block it would often just pop off, regardless of glue used.
If you started with a 1/2" thick belly lam, and worked the fadeouts into the thickness of the limbs, that worked, but wasted wood. It might cost you making four lams instead of six out of a nice, expensive ipe or bulletwood board. But, using scrap, the power lam would get you six.
Some people have had success dping it other ways, BUT, the BEST way seems to be a power lam that adds thickness under the backing, at least 1/16"-1/8", but a lot more than that is unnecessary. I only go thicker if I need to splice a backing . The tapers can be easily done on a tablesaw, bandsaw, beltsander, or with a hand planer and jig. With effort it can be done with hand tools.
That's how I remember it.
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I dig it so far. Be fussy about the glue joints. I'm a tad nervous about the 5 piece core; eAch joint and splice is a place for gremlins to get their fingers under.
And, if you NEED any stiffness or thickening at the handle, a power-lam under the bamboo would be the way to go.
Last thing about bamboo. Watch where the nodes go. The nodes are necessarily thicker than the rest of the backing. Not an issue per se, but if the stiff nodes line up with the wrong spot, you can compound your troubles. About 8 years ago, I built a BEAUTIFUL bamboo backed goncalo alves bow for a friend that pulled almost 70 lbs. Somehow, the node placement fell such that about 2" past both fadeouts there sat a bamboo node, making a transition from stiff fade to weak inner limb (highly strained area) to a stiff node in about 5" of the limb. I couldn't SEE it in the tiller, but I must have BADLY overstrained that 2" spot, because the bow fretted badly over the first 1000 shots or so. The belly was scribbled with little fractures, the bow took all kinds of set, and lost its cast.
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TTT, just cuz I'm watching to see how this goes :P
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Quick updat on this bow,
The bow is fine and I have yet to glue a backing on it because my time has been needed elsewhere. The time I have spent on bows; has been spent harvesting and processing staves before spring is in full swing. Lots of Hackberry, Redbud and some Osage, BL and Mulberry. Removing sapwood and sealing backs has been taking up a lot of time, but it will pay off down the road.
Another thing with this bow, I have gone through ~10 bamboo culms. There seems to be a disease or pest influencing my bamboo for the worst. From testing the Boo, I'm not happy with it. I will be using something other than bamboo and I'm processing that right now. So I will get the back glued on in the next few days and down to final tiller. The bow is very light weight so far (Literal weight not draw), it will be interesting to see how it turns out.