Primitive Archer
Main Discussion Area => Bows => Topic started by: WoodBenderDW on November 20, 2017, 09:42:07 am
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I had a reliable source tell me that bamboo backed hickory is a bad idea because the back will overpower the belly and cause the belly to fail. Yet, a lot of people people make bamboo backed hickory bows. Is there any truth to that? Is there anything that should be done differently? Should the back be trapped? Should the belly be hear treated? Will bamboo allow a shorter piece of hickory to work the way sinew would? Will a hickory stave that's 61 inches long work for a stiff handle recurve bow if backed with bamboo or is that still too short and better to bend through the handle? Thanks folks.
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Bamboo is very strong in tension. Hickory is also strong in tension but not so strong in compression. IMO, it is not a good combo. A short hickory stave is even more susceptible to compression failure if backed with bamboo, a recurve would add more stress to the hickory belly.
If I were to make a boo backed hickory it would be long and trapped with the hickory belly being wider than the boo backing.
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I have made a few BBH bows. all 3 of them were in the 65 in plus range and pulled from 40-55 lbs . All of them took a lot of set. and 2 of them have real bad compression fractures to the point where I didn't feel safe shooting them anymore and they got burned.. I think Bamboo is too strong in tension for the hickory. Ipe works great, I bet osage and any other pretty high density strong in compression wood. Keep in mind that I have limited experience with these materials
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Hickory is so strong in tension that for a 61" long recurve it would hold up better without a backing! Then if you insist on backing it, it is better to back it with maple or ash or even hazel because these woods match the level of compression for hickory better than bamboo.
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Yew back boo...so good they even made it rhyme :0)
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I have made 3 or 4 bamboo backed hickory bows, all were really sorry, poorly tillered hickory bows that other people had. I made a mistake and opened my mouth about how bad they were and the immediate response was "can you fix it ?"
I would take these awful bows and bamboo back them, all made really nice bows, none of them failed or developed frets. All were in the 40-50# range and at least 64" NTN. I made them all about 1 1/4" wide with very narrow tips and a non working handle. I would add a couple inches of reflex on the glue-up.
I found bamboo backed hickory to be almost as zippy as a BBO.
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Any backing and belly combination needs to take the qualities of each material into consideration, and change the ratios of thickness of both, bow length and bow width.
For strong backings likely to overpower the belly: make the backings thinner, and make the bow wider, and thinner or longer (so as to strain the belly less). Wider bows have more mass, so shift the most bending limb portions towards the handle (pyramid designs for example), so the mass is placed most where it has least negative effects.
Hickory is good enough in compression at very low moisture levels (5%). Toasting the belly will help (as heat-treatment reduces the equilibrium MC).
Bamboo-backed hickory bows can be exceptionally good, if designed very well. See for example Traditional bowyer's bible vol 3, chapter on "bows of the world". Plenty of examples there, and concrete suggestions as for ratios of different types of backing to core/belly wood.
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I have a Boo backed Hickory bow that is 7 years old and shoots great and I can't see it not lasting another 7 years.
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If I where to try,i would pre tiller to about 20lds at your draw,heat treat the belly and after glue up trap the back heavily.
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I ment glue a narrow strip of bamboo down the middle for the trap and adjust from there.
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Lots of opinions of what you should or shouldn't do from people who haven't made a BBH.
A few of us have made good bows from the combination, like any other bow making endeavor, design and dead on tillering is the key to success.
I have never trapped a bows belly in 20 years of bow making although I have seen it suggested quite often.
I have made a bamboo back oak bow that failed on the tillering tree but I suspect it was the gorilla glue I used on the glue up to see if it would work, it didn't
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Lots of opinions of what you should or shouldn't do from people who haven't made a BBH.
A few of us have made good bows from the combination, like any other bow making endeavor, design and dead on tillering is the key to success.
I have never trapped a bows belly in 20 years of bow making although I have seen it suggested quite often.
I have made a bamboo back oak bow that failed on the tillering tree but I suspect it was the gorilla glue I used on the glue up to see if it would work, it didn't
I guess you have a crystal ball or other means to determine someone's context!wish I had such marvelous powers!i have glued up several and reported my findings only to be little by the likes of you!by the way,the back is trapped not the belly!
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??? No experience with glue up, just reading and following. ;) :)
Pappy
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Wow! No belittling, just giving my experience with the combination, yours has been different and your input is a good thing. What I a saying is bamboo backed hickory can be done, I have done it a bunch of times, just offering a different perspective. There is no way I can predict what another person's outcome will be as we all make bows differently.
I was referring to the people who offer concrete advice like it is the gospel but with no actual experience, real common here.
I know what part to narrow while trapping, been doing this bow making stuff for 20 years, made a lot of bows. I think I am up to 154 that I know of and no telling how many that I didn't put down in my log book.
How many bows do you have under your belt?
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You can trap either side depending on your combo. I made two bows to establish that. ;)
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I was referring to the people who offer concrete advice like it is the gospel but with no actual experience, real common here.
I don't mean to be disrespectful, but allow me to disagree nevertheless on the question whether or not everyone without first-hand experience should stay shut.
The greatest advance in human culture was the invention of the script. Suddenly, being able to read meant you could gain information (=second-hand experience) from people you never met, and who may have lived hundreds of years before you. What's more, we live in an era of global communication. We also have access to all that information. All of us have learned to make bows by reading what others wrote, virtually none of us invented any aspect of bow making from scratch. This forum is the proof that second-hand experience is worth an awful lot.
I have never made a bamboo-backed hickory bow. I don't need to make one to know that it can make a great bow. Others have made great BBH, and have explained how, why and have the proof to show it. Others have studied in depth what bow designs are required to make good BBH. I'm merely transferring that information. I don't need the actual first hand experience to transfer this information, without it becoming less reliable. Even if I had made ten of them, that limited experience would be worth less to answer the question "can you make good BBH?" than all the combined experience on thousands of bows made by others, and recorded in writings.
That's the power of the written word.
And if that information came from the Traditional bowyer's bible, we can consider it "the gospel" on this forum, no? ;)
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Once I learned the bow making craft from experience and a lot of failures I was surprised at all the misinformation in the TBB series, some of the information in print is blatantly false from my experience. I call it fluff to fill pages.
Because the bow making world is so full of old wives tales and and misinformation I think we should pass on our actual experiences, not something we read and think is correct. This forum will be a much more reliable source of factual information if we do so.
This isn't bow making but an example of how quickly bad information spreads; On one of the M/L boards a guy is singing the praises of a gun cleaning product called Gunzilla. 5 or 6 guys chime in and say it is the best product to ever come out for cleaning a black powder gun, it gets everything, black powder residue, copper and lead and has no water in it so it won't ever cause rust.
I bought some and put it to the test; it gave the appearance of doing a mighty fine job, that is until I put my bore camera down the barrel. It looked like a coal mine in my barrel, black gunk I could get out in one pass with water was clinging to the rifling and breech plug.
I bet Gunzilla sold thousands of bottles from that one post. I bought into the myth, it wasn't until I had some actual experience that I found out it was bunk.
I bet the guys singing its praises don't have a bore camera.
My point is; actual experience trumps the written word by a mile.
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Are those pieces of info in TTBB based on the experience of another person?
Keep in mind you are passing on your experience through written word.
For every bowmaking "fact" passed on by anybody, some will fail and some will succeed. So what you found false another might find true.
And yes, errors in TTBB do exist and have been acknowledged by the authors and readers.
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Well.i guess I don't have the bow building experience enough to dispel other people's insight as pure fabrication .
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FWIW I have made several BBH's (after a number of failures). What I found to work is gluing in abuout 2-1/2 to 3 inches of reflex, trap the back so that it is roughly 60%-70% the width of the belly. I typically was shooting for a 45-50# bow and made them 63"-65" NTN. Basically a shortened stiff handle about 7" fade to fade, 1-5/8 to 1-7/8 wide for the first 8-10 inches then taper down to 1/2" with about 5-6" straight tips. The bows were tillered per Badger's mass method and never drawn past desired poundage. Typically they all ended up with about 1/2" to 1" of reflex left. I did make sure that I had both parts of the bow rough shaped and within about 1/16"-3/32" of finished dimensions before gluing up. (This doesn't include the trapping which I found about impossible to do before gluing). Also, as best as I could estimate, he Hickory that I used had an SG of .7 or better and flat sawn worked much better than quarter sawn.
Ken
PS - I typically tillered to 30" draw since I pull 29"+