Author Topic: On width profile and tiller shape.  (Read 1938 times)

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Offline Selfbowman

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Re: On width profile and tiller shape.
« Reply #15 on: January 28, 2022, 11:21:35 am »
Ryan I’ve said for some years it’s in perfect diminishing mass in my opinion. Ive ask lots of smart guys to give me those weights on a bow limb for years in 2” increments . The handles of my bows come in at about 7 oz on a fifty pound bow . The limbs on 67” ntn  with a ten inch handle weigh about 16 oz. mass is mass when it comes to wood. Less dense wood takes more wood in the limb. Hickory bows are bigger in actual size than Osage for example. The sooner you guys figure out perfect diminishing mass for a bow limb I think it will help you with distribution and where to put it in your designs. I could be all wrong on this but I’m not smart enough to figure it out for myself. I can only build bows and try. If you work with 8 oz on a 28” limb for example and the perfect diminishing mass that would be a startling point on a fifty pound bow . Then take those numbers to design the thickness and width you can play with a perfect diminishing mass on the computer. Just an idea from a not so smart guy. Arvin
Well I'll say!!  Osage is king!!

bownarra

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Re: On width profile and tiller shape.
« Reply #16 on: January 30, 2022, 01:33:15 am »
Ryan the reason the elb design would show the elliptical tiller more is that they are narrow to start with. The ipe elbs I make are generally 1" wide at the handle. This design doesn't have much room to taper in width - so they end up with a steep taper in the thickness. My rate of taper is around 0.009". A parallel limb flatbow may be around 0.003" and a pyramid 0.001! - 0.002" (per running inch).
If I don't get enough bend in the outer limbs you will get handshock. Or conversely too much bend middle/inner limbs will lead to a good thump. If the limb timing is off at all it will be significantly worse. The elb is a good bow to show somebody tillering 'mistakes' as the length accentuates any issues.

Offline RyanY

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Re: On width profile and tiller shape.
« Reply #17 on: January 30, 2022, 02:52:24 am »
That makes sense Mike. I didn’t consider idea of relative width of a given bow since it is proportional to draw weight.