osage board bows: 2 at once

[adb]

Hey, Scott

Nice looking osage boards!
Also, your yew Holmegaard looks great. The tiller looks very nice. What # did it end up at?

I wouldn't use cherry to back osage, either. Too weak. It does make not bad belly wood. I've made a few maple backed black cherry bows, and they turned out well.

Carry on, you're making good progress!

[radius]

The adb...the holmie ended up around 35#...pretty light...but that's okay since i'm giving it to my son who's 13.

[grantmac]

sure, Grant, that'd be cool!  Yeah, I don't know who gave you those sticks you gave to me, but they are definitely not Osage. 

You coming into town anytime soon?
Scott

I'm probably going to the Langford Windsor plywood sometime in the next few days, they got me some Ipe. Takedown longbow here I come!
       Grant

[radius]

OK ... Question for you guys?

Why do i never hear of anyone using osage as a backing strip?  Osage backed Osage?  It has  such a great reputation....do i need to back it, really? 

I won't use the cherry, and I won't use the black walnut (obviously) but GrantMac has a couple strips of hickory I can pick up sometime this week...but maybe there are other backing options as well....

[El Destructo]

I would not even think of bending that Board without backing it....Hedge wont take it..unles it is edge grained or biased cut....I would at least use Rawhide....but I would say Boo or Hickory as a Minimum

[Pat B]

If you are dealing with an osage self bow from a stave, a backing is not needed unless you violate the back ring or maybe if the rings are very thin. In the case of the rings being too thin, a raw hide or silk backing will be all you should need. A board bow, on the other hand has been sawn and thus the rings are violated. You can add a wood backing(I prefer hickory or boo), a cloth backing(silk, linen), a raw hide  backing or sinew. You could add an osage backing but you will need to saw off an unviolated ring to use as the backing because with osage ring violations are lethal. Hickory can stand some ring violations.
   Each wood had specific designs and working parameters that are appropriate. Some woods are good in compression so they will make better belly woods. Some are good in tension so they are good for backings or as standard self bows. Ideally, you want to match your belly wood and backing woods so you have a compatible combo along with the appropriate bow design.  Pat

[radius]

ok, so i went to the store and bought a half decent stick of bamboo, about 3" diameter with fairly well-spaced nodes.

Splitting it was dead easy with a little prybar:



Here are pictures of the back and belly of the split pieces, cut about 2 inches overlength:




And here is a shot of one end, so you can see what thickness and arc i'm working with:



gotta belt sand these suckers flat...should i taper them somewhat toward the tips, or leave them as parallel strands?  And i'll have to sand the backs, too, because they are dirty and marked up...this should be okay, right?

[Knocker]

Hi Radius,

I am glad you posted these bamboo photos and questions - I am looking forward to the answers.  Brian Melton gave me a nice piece of bamboo that had already been planed, but I would like to know a bit more about how to get there without a planer.

A question for you - Where do you buy bamboo that diameter? 

For other on the list - Can the bamboo be steamed to flatten it?  It seems like if you just shave it down, that it will be very thick in the middle and very thin on the edges...

Keith

[Pat B]

With the boo you want to reduce the thickness until you have a flat surface on the belly side then trace  the shape of your bow on the belly side of the boo and cut it out. Then reduce the thickness at the fades to 1/8" at the crown(the thickest part down the center). This will give you a razor edge down both edges and will also determine the width of your bow. You can also taper the thickness from fades to tips but only after cutting out the bows outline.  Leave the back of the boo(side facing away from the bow) alone until you are ready to finish the bow. The rind that is on there can be lightly scraped to remove it and most of the scars. A light sanding with very fine sand paper or rub down with 0000 steel wool should prepare it for dying or to add a finish. I remove only the corky part of the nodes but don't sand or scrape them. The nodes are the weak link in the bamboo chain. If you try to sand the back smooth there is a chance you will get into the power fibers. Look at the cut end of the boo, the closer you get to the outside, the denser the fibers get. The ones along the outside are the power fibers and that is where the strength is.    Pat

[radius]

Right you are:  check out these next photos:  it is very thin on the edges and thicker in the center.  Keep in mind that these pieces are slightly wider than the bows they are backing, so they will be glued on and then hand planed and this will make the edges a bit thicker...not much, but a bit...

I bought the bamboo at Rona, and i'm going to epoxy it on with G2 epoxy for oily woods...i bought some acetone, but I have this great epoxy so i'll just use that.

The first picture shows the work partway finished.  The second compares one finished backing strip to an untouched backing strip.  The third shows the final shape of both of them.







Now...any answers to my questions?  Here's more:

1.  Should i leave time for the bamboo to change before epoxying it to the back?  Some people say that it will take on moisture on the belly side, and so expand, and that this will cause delamination if not dealt with beforehand.

2.  I was left with a piece about 28" long...This will happen again after I cut more bamboo for my other 62 inch bows....can I join bamboo on the back?  Can the backing strip be 2 pieces which meet in the middle?

OK, gotta go...actually have important real life stuff to take care of today, and I gotta hit the gym if I'm gonna pull some 70# bows!!!

[El Destructo]

Radius....how are you getting your Pictures on here??? What site are you using...I like that you can add topics to your Pictures....I am using Photobucket...and I don't think I can do this...or at least I am not smart enough to do it!!!

[radius]

yank:

I use photobucket.  All I do is click on the image (it says "copied") then i open this window. I type, "Here is a picture blah blah blah," then hit enter twice, press control-V, and then hit enter twice again. 

Pat B:  Thanks for the advice.  Are you saying I shouldn't just laminate the two pieces and then cut out the shape?  That was my plan.  No good?

[Pat B]

You will want to trace the outline of the bow on the belly side of the boo first. Then cut it out to match the shape of the bow and reduce the thickness to the ultimate thickness(approx 1/8" at the crown). Ideally you want a knife edge along both sides of the boo after glue up. This will be reduced somewhat as you smooth out and round over the bows edges before finishing. If you reduce it first then cut it out the tips of the boo will be way too thick. That is not bad for the performance of the bow because the boo is physically lighter than the belly wood but it looks better when you thin it after cutting it out.
   Also, by adding some Perry reflex at glue up time will give you a better shooting bow with little if any set beyond horizontal and probably an inch of reflex after unbracing. I like to add about 3" of Perry reflex. I do this by clamping the glued back and belly to a table at the handle area and raise the tips, backing and belly, on to blocks(I use a piece of 2x4) before clamping the rest of the limbs. Also if you pre-tiller the belly wood first so it has an even bend when floor tillered you will get a nice even curve in your added reflex. Otherwise most of the reflex will be in the handle area with straight limbs.   Pat

[radius]

ok, that makes sense...thanks!

i'm getting the impression you've done this before...

so, i put the bamboo, as you last saw it, by the baseboard...i'll leave it there today...when i get back from town i'll probably be unable to stop myself from scraping away at the belly wood of these osage staves.  Not sure how much time i'll have during the coming week...first week of the month is always busy for me...but when i do get back to it, ill take your advice, trace out the shape of the bows, cut them, and then thin them again.  You know, they are pretty thin already!!!!  but you say an 1/8 th at the crown is what i'm looking for...then, alright, i'll look for that!

[Pat B]

I have made a few but to me they are more work then they are worth. I prefer a good self bow myself or hickory backings; which is as simple as it gets.      Pat