handle shaping through boo backing

[armymedic.2]

I see on here a lot where the handle area is slimmed down to be comfy on the hand, but when you do that through a backing, and make it slimmer than the limbs, i really don't understand why it doesn't break the bow.  aren't you cutting through the sacred back, and allowing places for failure?  i know you need to do it with care and not too much, but it just seems like it would take away the [point of the back on the outside edges of your limbs, because its fibers run up and down, creating a spot in the middle of the bow that has not support whatsoever.  can someone explain this to me please?

[Justin Snyder]

It is a lot safer on non bending handles.  If the wood isn't bending there chances of failure are slim. The farther from the bending areas, the safer.  I do like to keep at least some of the grain running all the way from one end to the other. If the handle is bending you are asking for trouble to narrow it to much.  Justin

[adb]

I'm not sure I completely follow you, but I think by your meaning that the only important thing is not to violate the backing throughout it's entire length. The bow's profile may widen or narrow, and usually does at the grip, but will remain very strong, as long as it's intact. As long as you don't cut through the back anywhere, it's OK. Also remember to keep things smooth. Try not to create sharp edges or abrupt tapers anywhere... they create weak spots.
Justin is also exactly correct about bending through the handle.

[Justin Snyder]

Here is an example.  The handle is completely rigid.  I had one just like it let go because it bent ever so slightly.

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[armymedic.2]

wow, that is an amazing riser.  ok so i guess what you are saying is that as long as the backing is not completely cut through, it is ok.  i was thinking that by narrowing it, you are cutting into, but not thru the backing.  i guess i was thinking that cutting into a backing that is fiberous, like boo, would render the length of the fibers that were cut into to be compromised, even though there may be a section in the middle of the backing that was not cut into.   simply rounding the back of the bow was what i was referring to, to do that you cut into the backing, but not through it.
 however that means you cut through the fibers that run along the outside edges of the limbs....making any sense?  clearly if that bow holds that you showed me, it is not a concern, but i was wondering why.   
so if the handle did not bend at all, technically you could cut through the backing completely  in the center of the handle, and it would not matter because no stress is appplied there.....so you could actually back with two strips of boo, meeting in the middle of a nonbending handle, and it would back the entire bow fine?   am i reading it right?

[Justin Snyder]

I wont say no stress on that part, just reduces the farther away from the bend it gets.  If I used two pieces I would wrap the center where they meet with something.  If your riser is long enough, it would probably work. Not a chance I am willing to take.  That handle I showed you actually has no fibers that run from one end to the other. But there is a tie between them to help hold the pieces from popping up.  Justin

[kayakfisher]

I agree with Justin on that the first few bows I built were Hickory and Bamboo backed bows .I used Resorcinal glue to laminate them  ,where the two ends of bamboo where joined together on the riser during tillering process one end lifted shattered the limb . We looked and looked for the missing limb couldn't find it .Finally found it ,it was fourteen feet up,stuck in the side of are Mulberry tree.Had to get a ladder to retrieve it. When I do bamboo backed bows using two pieces of bamboo I DUCT tape them  when tillering,then wrap with leather or put an overlay on the joint

[Ryano]

I've made lots of bows with the backings spliced in the middle.  Theres really nothing to it, just make sure its not bending there.

[tom sawyer]

Really the same thing holds true for selfbows with wide limbs that narrow in the fades.  You have fibers ending where you go from wide/thin to skinny/deep.  The key as everyone has said is to prevent bending into the fades.

Having said that, I've even made some semi-bendy handled bows that had slight narrowing in the handle area and also some movement.  So I think you can get away with a little bit, due to the support of the main section that is continuous.  My example is a 1.25" wide bow with a 1" handle, it stayed together just fine.  I also think this is less of a problem with woods that have significant cross-grain, you know the ones that are hard to split because of all the hairs you have to chop through.  This cross-grain holds thing together.  Hickory has significant cross-grain, so does osage, while ash and oak have very little.  Its why I like to split ash or oak for firewood, you aren't fighting every piece apart.

Finally, I must say that I've had a couple of bows pop on the tiller tree due to bending into fades.  The outer limb just splits back from the fade, leaving you with a ruined bow.