Primitive Archer
Main Discussion Area => Bows => Topic started by: Rcdeer on April 08, 2015, 10:31:15 pm
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have a #50 lefty longbow,,today the (maybe??) bamboo backing cracked,,not sure if hickory cracked but cannot see any sign,,, bamboo crack is on one of the "ridges"? the joint? and not sure what to do..hate to do anything to make it worse if its repairable..so haven't drew it full draw but what draw I've done,seems #'s are still there..any ideas? dang!! that makes #9 !!! bows broke or---disabled and this wasn't even at full draw! maybe 20" of 28" disheartening...... :'(
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Whether you can fix it depends on how bad the splinter is. If it's not too big you can try gluing a rawhide patch over it and wrap over that with thread. If it is bad you can remove the backing from the belly and replace it.
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Bamboo has high tension strength. Hickory has weak compression strength. Bamboo backed hickory is not really a good combination of materials. The glue line could have separated, but my guess is the bamboo node caused the hickory belly to collapse and splinter of the node/glue line.
If I'm reading correctly, that's 9 broken/disabled bows in a "row"? Take about 3 steps backward and make a "simple" design bow, maybe several of them, to get your confidence back and to hone your skill level. We're routing for you. :)
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Thanks guys,,, Gordon, the crack is not much more than an inch long..all the bamboo is there just split in seems two places..was thinking thread wrapping but rawhide won't hurt..thanks!
Gordon,,none mine! I haven't made one ,,these 9 are from 4 different builders, 5 snapped cracked ..3 lost tiller on one side thus #'s. and this one.... yet to be determined! it's tough breaking others without breaking my own,,not sure I could handle it!
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Fill the crack full of superglue and pretend it isn't there, I have done the same a bunch of times, node cracks are pretty common on bamboo and seldom fatal.
As for hickory not being a good candidate to back with bamboo........I have made 6 or 7 bamboo backed hickory bows and none ever had a problem of any kind. What surprised me about the combination is I could see no difference in performance between bamboo backed osage and bamboo backed hickory, I thought hickory would be sluggish in comparison.
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As for hickory not being a good candidate to back with bamboo........I have made 6 or 7 bamboo backed hickory bows and none ever had a problem of any kind. What surprised me about the combination is I could see no difference in performance between bamboo backed osage and bamboo backed hickory, I thought hickory would be sluggish in comparison.
Well there you go. What should or shouldn't work "on paper" is not always the case in real life. :) Because of the properties of hickory, I would have never tried this combination. One of the things I love about this site, I learn something new every day> :)
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I had the same issue because I sanded down the nodes too much. I wrapped each node with silk thread, and have shot the bow for the last 3 years, no issue.
Not sure how bad the crack is, but I started seeng the edges of the bamboo lift by hand. You can also use some long elk sinew which I prefer. Bad news is the bow needs to be about tillered before you can do this.
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thanks Eric..gonna try the glue,,the cracks really are not bad tore up .i jus wanted to see what i should do while it appeared minor..i don't believe hickory is involved in crack..i hope!!
big country,,thanks! like that idea of wrapping..still (omg!) thinking of taking bow down a little in pounds,hopefully the bamboo will hold while---if I try to do this....then, thread.......thanks!
Question! exactly what does the bamboo backing do? just for strength? or does it add #'s? thanks!
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Bamboo is used for backings because it is very strong in tension, and a bows back is under a lot of tension when drawn. Instead of protecting the back like rawhide or linen, it is the back. Bamboo is almost always added very early in the process, before tillering. To say it adds draw weight would be misleading at best since the bow would be designed with the bamboo in mind.
I'm sure someone with more experience can elaborate or correct me if need be, but that's the way I understand it. I hope it helps.
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Bamboo is very light in comparison to osage or hickory, you can get a higher poundage bow with low limb mass which equals better performance.
You can also glue in reflex or reflex/deflex in the bow making process to further enhance performance.
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okay..thanks! just to get it thru my head.... if a bamboo backed hickory bow measured #50....the # measure would be a lot less w/o bamboo backing? or the "strengt(durability) of the bow be less? sorry...seems with these bows everyday is a learning day...
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If you thin bamboo to the recommended thickness(knife edges) it is actually about the same weight as Hickory or Osage if not heavier.
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Number 9... it wasn't just the bamboo, I glued the bamboo..wrapped in sinew..5 pretty good shots then CRACK. dang,, :(
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Does the word 'rudder" feature in these bows anywhere?
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umm.. Number 9... By Rudderbow..thru Signature. first Rudder I've had.....just, maybe...maybe 40 shots thru it...
I've checked and rechecked everything I''ve done or do..had good shooters watch me..talked to many very experienced shoots and bowyers..all said, it's not me, but after 9 broke/unusable... I'm ....yup..disheartened.. to put it forum friendly terms.. best I just stick with my lil osage.. and hope my new holmegaard sticks around fer awhile..thanks guys!
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I have a Boo backed Hickory bow for over 5 years and never had a single problem with it. When I started to make another one I noticed that the bamboo was sanded all the way to the edge and the other edge was 1/8 thick and for a backing strip that was supposed to be flat it wasn't. I will never buy one from that company again. I don't own and power tools to be able to totally rework my materials before I start, sp from now on I chop down a tree.
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Bamboo specific gravity varies from the upper 30s to mid 80s, hickory is in the lower 70s and osage is in the lower 80s. Bamboo specific gravity varies wildly with age and grain structure. What I use is from 3 or 4 year old clums, definitely not hard and dense, so in my case my bamboo is light and strong and not near as heavy as the wood I back with it.