I just had my 3rd BBI break. The first I felt that I had not done a complete job with the tiller as I had the tips stiff about 12". The second and third were tillered to perfection working careful with the gizmo and really taking my time getting it right. All 3 shot well until they snapped with zero sign of failure until.... The first snapped about 8" up the top limb and the last 2 same distance down the bottom. My question is , does an BBI bow need to be longer than a BBO. That's the only thought that I have left as the ipe was very clean with very good bamboo.
Hard to say without pictures to see what may have caused your problem. The shortest Ipe I have used is 65" n2n 1 3/8 wide in a gull wing style.
Did the ipe give or did the boo fail?
I built an BBI that is ended up being under 60" tip to tip and is 70#@28 and have been shooting it off and on for about three years now. Its an inch and a quarter wide at the fades. So I don't think the length has to be any different than your BBO's. But I also had one that I built that was 62" tip to tip and I thought I had the tiller perfect and then it started forming compression fractures. Did the ipe from all three of your bows come from the same board?? There may have been a weak spot in the whole board if that is the case. Ipe is super tough stuff though.
Agree w/ the possibility of a flaw in the board --- just had two hickory bows develop hinges at the same spot from one board, so switched where I was cutting out of.
Different boards. Not even from the same source. The Bamboo held with no problems. I built a straight limb that I have shot most of the summer and is still holding together.The only difference is the 3 that failed, I tried more of a radius belly and not so flat as the one that is still alive. The third failure happened last night and I caught it before it snapped. I'll take some pics.
Here is a pic of the last mishap.
(http://i942.photobucket.com/albums/ad269/Onehair/98C03C04-F0F9-41A2-A2E6-77BDD63A0AAE-6264-000008524FC9217A_zps39dc4902.jpg) (http://s942.photobucket.com/user/Onehair/media/98C03C04-F0F9-41A2-A2E6-77BDD63A0AAE-6264-000008524FC9217A_zps39dc4902.jpg.html)
(http://i942.photobucket.com/albums/ad269/Onehair/9AE85B66-CAB6-4E3E-B686-9648E6DE97E2-6264-0000085259ABE098_zpsb6a8f60d.jpg) (http://s942.photobucket.com/user/Onehair/media/9AE85B66-CAB6-4E3E-B686-9648E6DE97E2-6264-0000085259ABE098_zpsb6a8f60d.jpg.html)
That appears to be a compression failure. Try making your bow a fuzz wider/longer, or making the boo thinner and tapered before glue up.
I'm beginning to think the "Brazilian Walnuts" are being grouped together when shipped over.
I fear Imbuia for instance may be getting labeled as Ipe quite often.
Both work fine for decking..which I believe is the main use of the wood.
Looks similar (when dark), both have the spicy scent when worked yet Imbuia doesn't have the bow making qualities of Ipe.
I tried a BBI a while back.
It checked almost immediately...before any decent belly wood should.
Used the same design on a BBO..still shooting...Really like the osage for working in comparison..easier to see your lines too.
I did build a tad narrower than I like but IPE is strong stuff and I was concerned about getting too thin. The boo is thinned and tapered nicely. I believe at this point I need to be wider and flatter across the belly as the fracture appears to have started in the highest part of the radius belly. I gave IPE high marks at first but I believe now Osage with all of the problems of getting good wood, is a better pick.
I've made,a lot of BBI bows. I do use a flatter profile.
Recently the wood has not been as good. Have had Crysal problems and the color between boards is more varied.
It's been hard for me to find decent Osage wood even though it grows all around me.
About to give up in Ipe. Still using Cumaru on light weight bows with no trouble.
I used up a lot of good osage working with bad bamboo. Got some good boo and now it's the belly wood that's causing the problems.
Macbow ... I have a cumaru bow thats 66" long, m,aybe 1 1/8" wide and draws about 43#@26" and have no real problems with it ... the tiller is nowhere near perfect either. Cumaru gets a bad wrap but it's not too bad .... At least you know youve got to be careful unlike bad ipe which you expect to be really durable