bamboo backed Birch

razorback · November 02, 2009, 08:56:00 AM

OK. I have possed this idea before and have seen it come up in a couple of other threads recently, so I think I may just go ahead and see what I can come up with.
What I need now is any suggestions that will help create the most probable design. I don't really care if it doesn't work just wont to see if it can. Also does bamboo backing have to be one piece of can it be spliced in the middle. I think I know but want to make sure.

ron w · November 02, 2009, 09:26:00 AM

I think you can splice the backing as long as you have a non bending handel/fade. But I could be wrong.....

soopernate · November 02, 2009, 11:07:00 AM

I personally would not do anything to compromise the backing at any point.

With that said however, I suppose one can splice it at the handle and then do a thin wood overlay for strength.

TheFatboy · November 02, 2009, 03:48:00 PM

I thought birch was quite weak in compression?

razorback · November 02, 2009, 04:36:00 PM

Thats what I've heard, but you never know what you will get till you try. I have done very little bow building so it will be very educational to do this build. If nothing else I will see first hand what happens when a belly wood is over powered by a backing. You never know, I may get a shooter out of it anyway.

dutchwarbow · November 02, 2009, 06:15:00 PM

Birch is ridiciously weak in compression. It will be crunched almost before you've started to floortiller it. Like backing Balsa with steel cable. Not even worth a try IMO.

Birch backed compression pine gives a nice bow, though.

Nick

razorback · November 02, 2009, 06:20:00 PM

What would constitute "Compression Pine". Have not heard that term before. I am interested in trying several varieties of wood combinations.

razorback · November 03, 2009, 04:31:00 PM

Soooo, if I was to do it anyone got suggestions for dimentions.

Pat B · November 03, 2009, 05:41:00 PM

Real long and real wide with a trapezoidal cross section favoring the belly.

razorback · November 03, 2009, 06:56:00 PM

Would 72"ntn and about 2" wide be long and wide enough.

Pat B · November 03, 2009, 10:45:00 PM

I don't really know. I would not build a boo backed birch bow. If you are learning to build bows I'd think you'd be better served building a bow using appropriate materials. Bamboo is a very tension strong material and birch is marginal at best. Not a compatible duo IMO. If you want to accomplish something build a birch selfbow. Use Paul Comstock's "overbuilt bow" design and you will have a bow, not a speed demon by any stretch, but a bow that will put meat on the table.
If you are just playing for the heck of it, then go for it! 2"x72" should do...but the boo backing that is 2" wide will be way too thick along the crown if you can make it that wide at all and maintain a flat glue surface.

razorback · November 04, 2009, 10:52:00 AM

Thanks Pat. I am toying with several projects for the winter and this is just one. Will check with some local suppliers and maybe get some wood that is more approriate for a boo backed bow. I have to finish a pesky Osage bow first and do one of 4est Trekkers board bows, before another bow.

AKmud · November 04, 2009, 01:04:00 PM

I tried a couple of white birch bows last winter and both exploded without warning during tillering. Mine were unbacked, but the way they blew, I don't know if backing would have saved them...

I'm done with birch!

razorback · November 06, 2009, 07:49:00 AM

I did one Yellow birch last winter and it blew after I had shot it hundreds of times. I got impatient stringing it one day and it went where there was a little wave in the grain. I'm still going to work with it a bit.

soopernate · November 06, 2009, 11:09:00 AM

Now also keep in mind it was just a couple years ago that these old guys said you couldnt back red oak with bamboo cuz it will overpower it and crush the belly. Then comes this guy in Hawaii who builds one that has cast THOUSANDS of arrows. In the Traditional Bowyers Bible VOLUME 4 it suggests that bamboo can work with most any wood if it is NARROWED (not thinned) appropriately to decrease the compression forces on the belly. Personally I have three bamboo backed bows:two with maple bellies which I was told would not work and one of the aforementioned red oak.

razorback · November 06, 2009, 12:17:00 PM

Thanks Soopernate.
A fresh perspective is always good to get. If we didn't try new things nothing new would ever get done.

Dano · November 06, 2009, 01:40:00 PM

"Now also keep in mind it was just a couple years ago that these old guys said you couldnt back red oak with bamboo cuz it will overpower it and crush the belly. Then comes this guy in Hawaii who builds one that has cast THOUSANDS of arrows. In the Traditional Bowyers Bible VOLUME 4 it suggests that bamboo can work with most any wood if it is NARROWED (not thinned) appropriately to decrease the compression forces on the belly. Personally I have three bamboo backed bows:two with maple bellies which I was told would not work and one of the aforementioned red oak."

Keep in mind it's comments like this that are the reason most of the "old guy's" aren't around these forums any more.

4est trekker · November 06, 2009, 02:16:00 PM

Man, what I wouldn't give to sit down and talk to some of those "old guys" I'd love to watch 'em shoot, make shavings, and talk about the good old days! It's amazing what some of those old boys could do with a stick and string! Thanks for reminding us, Dano!

soopernate · November 06, 2009, 03:56:00 PM

I apologize Dano. That was not meant to insult anyone of ANY age range. What it was mean to do was exactly how razorback took it. Encourage people to try new things. I personally love it when guys tell me you cannot back red oak with bamboo because it will overpower it and crush it while I am shooting that example right alongside of them and proving to the contrary.

dutchwarbow · November 06, 2009, 04:24:00 PM

yup.

you could also make a huntworthy bow from balsa. It'll have 2foot wide limbs, but it might shoot.

you could even back it with bamboo, if you take a 1/16" wide piece.

but.

why back birch with bamboo if there are so much more, better suited backings around?

if it's a really bad-grained board, try maple as backing, and trap it additionally. As birch was usually used as backing wood, instead of compression wood, another well-suited wood would be ... indeed, birch.

As birch is so ridiciously weak in compression, you might even want to back it with an even lighter wood, ie. pine. Backing it with lighter woods will make it alot easier to make a high-performance birch bow.

I hope you have some experience with bamboo. I tried a bb-maple, and I just felt how the maple was crunched. the bow took 6" of set after being drawn a full 20".

personally, I wouldn't really give birch a try, exept as a backing on a compression-pine belly, like the saami bows, or as a trapped selfbow.

Nick