Bamboo osage question

[Lee Lobbestael]

I'm starting a bamboo backed osage r/d bow shortly here.  What kind of taper should I cut the osage to before glue up? Is going to be 66" ntn and 1-1/2" wide. I was thinking 1/2" at the end of the fade and a straight taper to 1/4" at the tip. Is this too thin?

[Dances with squirrels]

That's too much taper in my opinion. I usually taper the osage no more than 1/8" from dips to tips prior to glue-up. I generally don't have to, but you could always remove more during tillering if you want more movement in the outer limbs. The bamboo will/should be tapered as well, so keep that in mind since it factors into the overall taper.

As far as thickness, I keep the thickness parallel from dip to dip, and then taper from there out towards the tips, but rarely make it 1/2" thick in the middle. 1/2" of osage, tapered for even limb flexing, can easily make a 70# + bow at the length and width you mentioned.

[Lee Lobbestael]

Hmm I was planning to make my bamboo 1/8" the whole length. This is a bad idea? Not sure I have a way of accurately tapering it

[Eric Krewson]

I make mine 1/16" on all the edges from handle to tip with a flat belly, this naturally tapers it.

[Lee Lobbestael]

So you must cut the profile into your bamboo first Eric? I have only left the bamboo full width until after glue up

[Dances with squirrels]

Yes, flatten the inside of the boo, lay a pattern on there, trace it, cut it out, then thin the boo so that it's no more than 1/16" all around. This 'automatically' tapers it in thickness because of the crown and width taper.

Note: ... no need to cut the front profile of the handle area out until after glue up and any additional handle piece has been put on too... so during this initial thinning process, the boo can be the same width from dip to dip.

[Lee Lobbestael]

Ok so I assume you do the same thing with the osage then huh

[Aaron H]

Good advice above, especially leaving the handle full width until after glue up

[Springbuck]

Hmm I was planning to make my bamboo 1/8" the whole length. This is a bad idea? Not sure I have a way of accurately tapering it

Either way is fine, and guys that taper their bamboo produce some very nice bows around here.       I never taper the bamboo, and it doesn't seem to affect the tips as far as the bamboo beating up the belly.  UNLESS the bamboo is so thick that your belly lam gets ridiculously thin.  Like, I wouldn't want to end up with a tip having 3/16" bamboo and 1/8" osage, right?

As far as the belly lam pre-tapering, don't go that severe.  Half the thickness is too much, esp since the tips will be narrow and have rounded corners, etc... by the time you are done.  Start maybe 1/2" thick and end more like a fat 3/8", esp if you expect the bow to have any stiffness to the tips, which a shorty bow should.

I commonly use a power lam in laminated bows specifically so I can start with less wood thickness, I.E, I can get more lams for my money from a good board.  With 1/8" thick backing and belly that runs even from a fat 3/8" at the fades to 1/4" at the tips, I can get a pretty high draw weight bow, even if 68" long or so, BUT, I am using Perry reflex, I am using  over 1-1/2" of width (since I generally am NOT using osage, rather BL, Goncalo alves, massaranduba, etc. AND I am using a power lam AND reverse tapered wedges (1/16" thick or more).  You'll be sorry if you don't have enough thickness at the fades or tips, for sure.