Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: Dustin Gilstrap on May 26, 2015, 10:22:00 PM
-
I am on my second attempt at a bamboo backed hickory belly bow. My first one snapped 4 inches from the lower limb tip. I tried to heat treat it and give it a little reflex to get rid of the set and probably caused its demise. I either over heated it or clamped it too tight after heat bending the limbs. I used smooth on before heat treating and I may have affected the strength of the glue as well. All and all, it was a learning lesson. Bamboo is a weird wood to work with. I think it causes the bow to take a set it seems to want to flex away from the back. Any ideas or tips on heat treating a glued up bow? Any advice on stains used for bamboo? I have noticed the standard traditional stains do not seem to work and I want the back of the bow darker for hunting. Is hickory a good belly for a backed bamboo bow?
-
Osage or ipe
NO heat after glue up
check out tenbrook archery in the classifies
I have some VERY high grade Bamboo and Ipe I would like to sell.
The Ipe is hand selected by me. I usually go through hundreds of boards before I find just the right one. The grain will be very straight and the wood nice and dense. They are cut into 72"x 1.25"x 3/4" pieces. These pieces are a full 3/4+" thick giving you enough wood to do 1-2 BBI bows depending on the desired draw weight.
The Bamboo is the Highest Grade Bamboo Slats they sell and a full 8' x 2". I will chose the best 72" (based on node placement) and cut before shipping.
The picture is just some of my supply. I have a TON of this stuff.
Use this link to checkout: http://www.tenbrookarchery.com/store/c2/Bow_Building.html
-$49 (for one piece of Boo and one piece of Ipe).
-$18 Bamboo Backing Only
-$38 Ipe Only (72"x 1.25"x 3/4")
Thanks [thumbsup]
-
Bamboo is probably the weirdest wood of all to work, because it's not a wood! Technically it's a grass, so everything you think you know can & will be turned on its head. Thanks, Bamboo.
Since bamboo is very-tension strong it needs a compression-strong timber to act against it in the belly. Osage & Ipe are good examples of such a timber.
Hickory is one of, if not the most, tension-strong wood commonly used and makes a terrific backing. It's above average for compression-strength but nothing special. It can be used as a belly wood but my preference would be for something else, particularly with a bamboo backing.
-
Thanks Nezwin and Mark Daniel. Have either of you ever stained bamboo? I am looking to stain this next bow for a less visibility. Nezwin, what kind of cool wood is locally in your area in Australia. I found some Russian olive here recently that I am going to try out down by the river. Any cool local wood there that makes a good selfbow?
-
Bamboo dyes well with alcohol or oil based aniline dyes. It will go as dark as black.
Bamboo doesn't cause set. Any set was most likely due to design and/or tillering.
You should not heat treat a glued up bow. If the blank was cured with heat during glue-up, you can very carefully make minor heat corrections for alignment, but I wouldn't heat treat it.
-
Oh and just for the sake of clarity, a bamboo backed bow, or any backed bow, isn't a selfbow. A selfbow is an unbacked bow... It is self-backed.
-
Aniline alcohol dye works great on boo, but you need to remove the rind first, and don't sand off anymore on the back than needed to remove the rind.
http://woodworker.com/jemosers-alcohol-soluble-brt-yellow-golden-oak-aniline-dye-mssu-845-541.asp?search=aniline dye&searchmode=2
-
What bowjunkie said -- a self bow is one stick of wood -- no other materials, no other wood. What you've made is a wood-wood or wood-bamboo) composite bow.
I've built several bamboo self bows, but they take a seriously thick culm to start from. Mine are built the ancient Chines way -- with the rounded outside of the culm as the belly of the bow.
-
FWIW, hickory can make a nice bow, especially in a dry climate like NM. However, I think everyone here is spot on that hickory is not the best wood to stand up to the beating that bamboo will put on it.
Hickory selfbow or hickory backed hickory would be better. Or as mentioned, if you wanna use bamboo, use Osage or ipe belly for best results. Lastly, you could also trap the bamboo back to reduce the compression on the hickory belly some, that would probably help.
-
You should glue in the reflex to your bamboo backed bows instead of trying to add it later.
I have found that 3" of reflex will give you a shot in bow with straight limbs or 1/2" to an 1" of reflex.
(http://img.photobucket.com/albums/v181/ekrewson/bow%20making/bboglueuptable.jpg) (http://smg.photobucket.com/user/ekrewson/media/bow%20making/bboglueuptable.jpg.html)
-
Originally posted by Dustin Gilstrap:
Thanks Nezwin and Mark Daniel. Have either of you ever stained bamboo? I am looking to stain this next bow for a less visibility. Nezwin, what kind of cool wood is locally in your area in Australia. I found some Russian olive here recently that I am going to try out down by the river. Any cool local wood there that makes a good selfbow?
Check out www.poorfolkbows.com (http://www.poorfolkbows.com) for clear instructions on staining 'boo.
Australia has a bunch of different woods to the Northern Hemisphere, there's still a lot of trial-and-error research going on for people to work out what is usable and what isn't. It would seem we don't have as many options as you fellas but we do have Osage as an introduced species, which is a god-send! But for natives we have -
Ironbark (comparable to Ipe maybe?)
Spotted Gum (again, closest species you have might be Ipe. Works well with a bamboo backing)
They're basically compression timbers that rely on their density for strength as opposed to any inherent timber properties.
There's also -
Queensland Silver Ash
Sydney Blue Gum
Celery Top Pine
But they're a bit untested, to a degree. Not commonly used enough for surety, I'd say.
We also have access to Hickory, Red Oak, Rock Maple, Ipe & Lemonwood in board form, which makes life easier. All shipped in from abroad, ofcourse, so they're not cheap (except the Red Oak, which is still more expensive than over in the States).
Up in the tropics there's a bunch of other timbers suitable for selfbows and there's people who reportedly have done well with a few Wattle species but we don't have the population (or camaraderie!) of North America, so there's less knowledge sharing. Shame really.
I read on one forum where someone had suggested that, maybe, there's no need to chase rings on a few native species... If that's true, then we would have a lot of very cool & easy to work timber species :)
Best bloke to answer this is BigBob though. He's based in Queensland, I believe, and he's been making bows way longer than me.
-
Thanks for the responses all. I am new to this but very exited about turning out a few bows this year. Thanks for the advice. I decided to not do a stain and leave the bamboo natural after all. I will post a few pics here in a bit.
-
It shot really fast. Still trying to mess around with arrow weights/nock point. Seems like the arrows are not flying as straight as I wanted but turned out pretty good overall. I will try a different belly next time with the bamboo.
(http://i.imgur.com/vTlPBCS.png) (http://imgur.com/vTlPBCS)
(http://i.imgur.com/XSJooOd.png) (http://imgur.com/XSJooOd)
(http://i.imgur.com/NqGFjqK.png) (http://imgur.com/NqGFjqK)
-
Nice job. It could use a tad more bend right outside of the riser ends. It will most likely want a lighter weight spine arrow, like 10# lighter than the draw weight.
-
How thick is your bamboo?
Hickory should work well if it is good quality and you properly design and craft the bow.
But you need to get the bamboo thin. Do this by cutting out the profile of the bow on the bamboo before glue up. Then thin it so that the side thickness is less than 1/16" all the way around. Then glue in 2-3" of reflex on a 1/2" (or less) thick slat of quality hickory.
Get Dean Torges' video "Hunting the Bamboo Backed Bow" bowyersedge.com
-
As an alternative to Ipe and some of the others suggested, what about using bamboo flooring for the belly?
homebru
-
I wouldn't advise it. It's not great in compression.
A bamboo bellied bamboo backed bow can be great but isn't really a beginner's design as you need to pre-taper both pieces or use a tapered core.
If you wanted to go down that route you use the outer crowned surface as both the belly and back. Heat treating the belly piece BEFORE glue-up.
Personally though for ease I'd recommend bamboo backed ipe. A really great combo :)
-
x2 what mike said,
but as a matter of interest check out a BBB bow that wood carver 2 built
cheers
wayne
-
The bamboo is 1/4 inch thick. I think it may be too thick. I will check out the vid. thanks john
-
It should be 1/8" at the handle and 1/16" at the tips.
-
check wood carver 2 swap bow.
certainly a pretty advanced way of building a bow- but well worth beholding!
-
I don't know about it being an advanced method, but it will for sure frustrate you and make you wish you were building with glass. ;)
I started building them after I saw one built by Forest Trekker posted here.
Through trial and error (lots of error), and advice from the Gang, I have come up with this:
bamboo backing is 1/8" tapering to 1/16" at the tips. Flatten this piece, cut it to the bow's profile, and then bring it down to it's final thickness and taper.
For the core, 3/16 tapering to 1/16 should get you into the 40+ pound range.
Flatten the belly lam then heat treat it before final flattening and thinning. I use a torch, going over the boo carefully to avoid burning it. You will see steam coming out of the ends and you'll notice that it cups backwards from the heat. I see this as a good thing as I can now get it really flat and thin. Again, 1/8" tapering to 1/16". It can be thinner if you can manage that. I use a jointer and two push pads, but it's still an adventure. A belt sander will work too.
I also prefer a width of 1 3/8" for these bows.
Good luck and post pictures.
Dave.
-
That's what I thought. When you have too high of a proportion of bamboo, your belly slat gets too thin and compresses under tension. Also, you invariably end up with too much mass at the tips and therefore get a doggy shooting bow.
Get Dean's video. He was responsible for the education of most of the folks who make bamboo backed bows, either directly or indirectly and stands as the master of the craft.
He also has a companion tillering instructional that you should get. His selfbow book "Hunting the Osage Bow" should be required reading too :)
-
I'll second everything John says, plus it bears repeating that the tool of choice for the final thicknessing of your bamboo backing, or belly for that matter, is a toothing plane with the blade every so slightly crowned. Of course, thinning bamboo can be done with a rasp and scraper or power sanding equipment, but none of these can do it as precisely and as quickly as a toothing plane. If you take pride in your glue joints, get a toothing plane and learn how to use it. :thumbsup:
-
Those last couple of posts harbor some very good advice and I concur 100%.