Happy Friday everyone.
Been makin' em and breakin' em for a while now. This forum has been an invaluable resource in my journey. I look up to all the amazingly talented bowyers on Primitive Archer. Another invaluable resource has been the Traditional Bowyers Bible series and Bows and Arrows of the Native Americans. I've got a small handful of long-term shooters under my belt, most of which were given away to family members and friends. One recent development that I've been having trouble with is pyramid bows that break at the fades.
The three that have broken recently let loose after shooting in, finishing, and 500+ shots. One was a rift saw oak board at 55#, and I can see where the grain orientation might have caused that break. The other two were a decrowned hickory stave pulling 90 pounds, and a flat saw hickory board pulling 70 pounds.The lower weight bow had a slightly bendy handle and the heavy ones have glued on handle risers. I leave plenty of thickness near the handle, and have never had one pop off, so I'm sure the riser area isn't bending. I've only used rift saw or flat saw boards and decrowned staves up to this point. I haven't got any seasoned staves ready for a single ring back just yet. I use an eliptical tiller. I try to keep the first 6 inches or so out of the fades bending minimally, majority of stress focused in mid limb, and the last 6 inches near the tips stiff.
I broke enough of them due to bad tillering in the beginning to have a pretty good general idea of the tillering process. I'm not developing crysals or hinges anymore, so as far as I can tell my tillering is satisfactory enough to keep them together. (I don't have any tiller pictures of the bows that have broken as I'm out of town for the weekend)
Here are the 'general' specs for the lighter bows:
64-68"
2 inches wide limbs straight fading to 1/2 or 3/8 tips
4 inch handle, 1-1/2 deep
2 inch fades, with the fade going into the working part of the limb and always past the widest portion
Here are the specs for the heavier bows:
66-68'
2.5 inches wide taper to 1/2 or 3/8
4 to 6 inch handle, 1-1/2 deep
2 inch fades, same principal as above
They're lifting massive splinters that are half the dept of the limb and 6-8 inches long, always right on the top limb's outside points of the fade. All three in the same spot and all three rendering the bow useless.
I've borrowed a photo I found on google that's linked to PP to show the tiller shape I use, so I hope no one minds my borrowing it for illustration purposes. I'm also drawing up a sketch of the breaks which I'll post in a moment. Hopefully once I've got the illustrations up you guys can give me some guesses as to what's happening. I'm clueless.