Are all limbs the same shape?

[O.L. Adcock]

Jeduffy, you ask tough questions! I think if you took 10 sets of limbs, ranked them by shooting qualities, all that subjective stuff, and performance, laid the top 3 side by side, you'd see very little difference between them. You have to figure there has been a lot of sharp people working on optimizing the GM geometry for 20-30 years. When locked into a single riser geometry there is only so much you can do to a limb that isn't lipstick and polish. Until they figure out how to use high quality carbon (requires a different design) and/or find another material with a higher stiffness to weight ratio, target recurves have about as fas as they are going to....O.L.

[JohnK]

Well, the geometry Earl Hoyt came up with has been modified quite a bit, especially recently. You only have to look at the differences between some of the currently available risers and limbs to see that.

As for that double curved limb shape, I remember discussing Greenhorn's attempt with a very skilled bowyer. I asked him whether or not the points in the limb where the curve changed sharply wouldn't act as focal points for stress, and he said they probably would. I'll stick with a smoother, gradual recurve, at least on a target limb.

[O.L. Adcock]

John, Are the limbs from 10 years ago interchangable on todays risers?? If so, the geometry hasn't changed, the limbs are set at the same angle in relation to the grip/riser. Cosmetics only have changed.....O.L.

[JohnK]

Well, by that argument the geometry changes all the time, because you can adjust the angle by turning the limb bolts. Also, some risers (e.g. the Best Zenit/Border Talisman) had a wider range of adjustment than others.

Also, the centre point of the bow varies between risers. You only have to switch limbs from an Intrepid and X Factor riser to see that.

[O.L. Adcock]

Those are small insignificant changes. Case in point, the best FITA limbs today don't perform any better then ones 10-15 years ago. Bows of different geometry will out perform FITA bows by 10+%....O.L.

[jeduffey]

OL - I checked out your website. I was very impressed by your limb design. One of the hallmarks of a good design is that it seems simple enough that you look at it and think it should have been thought up years ago. With 'and' in mind it makes me wonder how something like a Hoyt Trykon, specifically the split limbs would behave if the design of limbs was combined with yours, plus the power of cams. I'm not saying cams make everything better, just what happens when this 'and' that are put together?

Admittedly, most of this postulating was brought on by a read through of the BowyersJournal.com design contest rules. I scribbled out a drawing and some specs that sound nice. Having never made a laminated bow, I haven't the faintest clue if any of it would actually work. I'm certain that I'd get a bow that shoots, but with who knows what qualities.

That being said, I was also wondering how the ACS technique would work in two other modified versions. 1) would natural lamination materials tolerate an ACS formation? The BJ contest rules state natural materials. 2) If one were to start with a small enough limb of a suitable tree, such as osage, how would it perform if, after carving the back down to one growth ring, the belly was carved down to one single ring too? Keep in mind that on a sufficiently small tree limb, 6" diameter or less one single growth ring on the belly should generate a natural imitation of the ACS design.

-JeD

[JohnK]

Originally Posted by O.L. Adcock

Those are small insignificant changes. Case in point, the best FITA limbs today don't perform any better then ones 10-15 years ago. Bows of different geometry will out perform FITA bows by 10+%....O.L.

I don't buy that, but then you knew that already.