My horn bow build-a-long

[DC]

You've got a lot more faith in me than I do

[stuckinthemud]

For what its worth, this has been one of the most valuable threads I ever read, so thanks for posting all your trials and tribulations.  Gutted for you this one didn't work out, hope to see you posting a follow-up thread one day.

[DC]

I'm going to have to read it again. Obviously I missed something

[Deerhunter21]

For what its worth, this has been one of the most valuable threads I ever read, so thanks for posting all your trials and tribulations.  Gutted for you this one didn't work out, hope to see you posting a follow-up thread one day.

Yeah, if your done I say we archive it

[JNystrom]

Too bad it broke DC. It happens, some break more, some less. I've glued up some 10 bows now and i've had very little success this far. Those longer bows (mongol, molche balka etc) would be good starter bows to get a hang off things. I don't mind the breaking though, since its so fun to build them.  Just need to see the light in the end of tunnel, it might just not be a train approaching...

About your bow, it is quite common practice to repair old bows that for some reason break/delaminate the horn belly. The way you do it is by first getting rid of the old horn by heat and wedges, or just by grinding it away. Then just the normal glue up with built up sizing coats, but the final clamping is crucial. The glue up shape of the limb should be as close to the other limb as possible. Its doable, but needs some skill also. I haven't personally done it, but i have some bows that would need to have it done.
If you don't like the bow in the first place, don't do it.

[DC]

The glue joint appears solid. There are bits of the horn still glued solidly in the bottom of the grooves. The horn just self destructed. I'm very impressed by the strength of the glue joint. I've convinced myself that the design was the problem so the other limb is probably just waiting to break. Moot point anyway I'm soaking the sinew off as we speak. It will be interesting to see what the actual thicknesses of the three layers are. I'm still debating what to do next but I don't have any perfect maple. I know of a tree and it's just about loose bark season so I may cut it. I would have to make a decision on what to make so I can steam bend it while it's green.

[Pat B]

I remember James Parker and his brother in law(disowned), Vinson Minor trying to brace for the first time James' first Asiatic horn bow(90#) and breaking it in the process. There were a few choice words blurted out.
 Too bad your bow broke, DC. Lots of hard work in it I'm sure. Have you preformed an autopsy?

[DC]

I think it was my design Pat. I misunderstood and glued a bunch of reflex into the sal area when I glued the core and horn. This put too much stress on the horn when I tried to bend it. The horn just exploded. The inside of the horn stayed glued to the core and the outside popped off so I'm confident that the glue joint was good. I'm soaking it to get the sinew off. It's been soaking for 4 days now and the sinew is starting to peel off in big pieces. The horn is just starting to lift out of the grooves where it tapers right out. This hide glue is good stuff.

[bownarra]

Dc If the horn had been sound you would be amazed what a composite limb can take. Remember what Adam says about this subject. It wasn't the design.

[DC]

Dc If the horn had been sound you would be amazed what a composite limb can take. Remember what Adam says about this subject. It wasn't the design.

OK, now I'm confused. You mentioned early on with the build that there was a problem with my bow. Adam says not to put too much reflex in the sal. I thought that was it. On a side point when I was first trying to brace it and it flip flopped the limb that bent the most was the one that broke.

[Deerhunter21]

I would probably say a combination. you said the horn was cracked. horn can take a lot of stress according to bownarra. the bow was stressed a bit more than it should have in the sal, but it should have still survived. so, crack + a little too much reflex on sal + limb twisting = broken bow in my mind.

[bownarra]

That design flaw (reflexed sal) would possibly lead to a delam of the horn core joint. The crack in the horn appears to have been the problem that caused your failure. Of course it is hard to say for sure from the other side of a computer! I never had the bow in my hands so take whatever I say with a pinch of salt

[DC]

Once everything is soaked off I'll post pictures of the horn. It may show something. I'm not 100% sure the cracked limb is the broken one but we'll see. The sinew is all off and one piece of the horn is off. I see what you mean by don't wait for the horn to soak off. The good limb is hardly showing any sign of coming off.

[DC]

I gave up waiting here's some more pictures. Everything is oriented as it was. I'm pretty sure this was the cracked horn. I thought the CA would show but the horn flakes much like the CA when it breaks. It looks like it broke along the cracks but I think it would do that no matter how it actually started. The thing that makes me think that the horn broke is that all the pieces were still nicely glued in the gooving. It didn't just collapse like I've heard horn bows do. It went off with a bang and that centre piece was stuck in my rubber floor mat.

[Deerhunter21]

yeah, to me that looks like compression failure in two places among the horn