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Further ideas on flattening/processing?

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MattZA:
Hi all,

I recently got hold of a pair of Gemsbok horns. Using a dremel and a carefully laid out line, I cut the straighter of the two horns in half. The left one half of a horn in a reflexed position and the other half in a deflexed position. I soaked the horn in water for a few days and straightened the deflexed half so it was straight.

I then needed to get to the flattening of the inside concave part of the horn, which was approximately half of it's length. Having read Ed's how to guide I used my gas top stove (unfortunately I don't have a heat gun) to heat the horn over an open flame. I've used an open flame exclusively for any dry heat, so I have a decent feeling for how to heat without burning.

Vise at the ready, I heated up 3" of the thick end of the horn for a good few minutes and quickly put it in the vise. as I closed the jaws, I heard a crack. Lo and behold, the horn cracked exactly at the "crown" of the half. The crack is just visible from both the inside and outside of the horn for about 2 1/2".

I naturally assumed that the horn was too thick to bend, so I thinned it out with a dremel round grinding tool and then sandpaper to make it even. It's now around 1/8" thick when viewed down from the thick side. I tried again a bit further along the horn so that the crack couldn't interfere, and once again it simply cracked without so much as bending a millimeter.

I was considering simply taking down the sides with a draw knife as you would do with bamboo - but that would probably only leave me with 7/8" total width at the widest as it narrows down to the tip.

Am I missing anything about the process? Is the horn still too dry despite days of soaking? Is my heat not sufficient? Is it too much and therefore making the horn too brittle to bend?

Alternatively, could I use a horn strip less than an inch wide to make a 44" Turkish bow? I'm only looking for approximately 50# draw weight at 29". It'll be attached to either a bamboo or a balau core which are both 3/16" thick.

Thanks a lot,

simk:
Hi Matt

I haven't done it but I have a nice book (Wolfgang Gailer, Skythenbogen in German) where the process is described in words and pictures very well. Basically he says, that the oryx horns are more difficult to shape with heat than buffalo as it's more brittle and more fibrous. As far as I understood the process is the following: Need to soak the halves one week, then cook them for an hour minimum. Then step one: Widen the half with a long round pipe and clamps - the pipe looks like a diameter of around 150% of the horn. This is required to prepare the further flattening. After the half is widend that way you can finally flatten it in between two hot, thick metal/steel plates (looks to me like 8mm on the pics) - and clamps of course.

He also writes that for narrow horn strips the horn can also be cut in quarters. It is also possible - and in the total easier - to lay a pair of them parallel on the belly...

...thats maybe the direction for you now, as the strips splitted...

For competent help just contact the author on his site (or on facebook) - he is english speaking and very generous with advice. Good luck with your build.

Cheers   

MattZA:
Hi Simon!

Long time no speak. Good to hear from you :).

That's such excellent advice. The piping idea seems so obvious when you have been told already.

Fortunately, I have another horn (much longer, but slightly twisted). Each one cost me about €5.50. Talk about the advantage of living here! So even if I mess this one up, I can always use the second one or just buy a couple more.

I shall definitely contact him, thanks a lot. Fortunately my fiancé is fluent in German (having lived in Leipzig as an exchange student for 2 years). So even if he needs to offer me his book I can buy it and beg the lady to translate it! Ha ha.

The horn is currently back in soaking. I thinned out the inside on the second half yesterday. I'll give that a try with Herr Wolfgang's method.

In a worst case scenario I will be able to use them as quarters no problem. I'm glad that he says it's a viable option to do that. Might actually be my best option now I think about it, because I can face each quarter in opposite directions so there a wide and a narrow side along each end.

Thanks for all the advice!

Cheers,

Matt

bownarra:
Horn should be heated to bend it by steaming or boiling. Dry heat is a bad idea as you have found out. 10 - 15 mins steaming/boiling is all you need. Anymore time and you are weakening your horn significantly. If it won't bend after this amount of time you are asking too much of it.
Gemsbok are best used on a convex core/concave horn joint.
You would only need 1 inch or more width in the bending section of the limb after that you will be narrowing anyway.
Do not use balau for the core. Bamboo is ok but make sure the nodes are centralised on the handle and the next ones are past the kasan eye.

MattZA:
Thanks for the input, bownarra!

I think I've seen every possible contrasting piece of advice about flattening horn. Some people on this site recommend dry heat. I've also seen streaming, boiling, frying and soaking in milk as other options.

I tried steaming yesterday on the uncracked half of my gemsbok horn. Steamed for exactly 12 minutes. Exactly the same result. It cracked for about 3" right on the crown from the base of the horn the second I began squeezing it between the boards. It gave me about 2mm of "give" and then cracked. At first I thought I took too long to move it from the steamer to the clamps, but I did it in about 5 seconds. Surely that's not enough time to cool the horn down too much.

The horn I was trying to flatten is 3/16" thick, so it's not even like I tried to flatten something too thick...

I've decided I'm going to split the horn into quarters along where it's already cracked. I'm not going to even attempt flattening it any more. I'm just going to rasp the concave inner section of the quarter until they're flat. Then I'll glue on 2 quarters per limb lying next to each other. I just need to work out how I'm going to flatten the outer of the horn without losing literally all my thickness. Currently the belly would have two mini crowns in an "m" shape - which I'm sure isn't ideal.

Why would you not use Balau? I've got massaranduba as well. I've tested the bamboo and managed to steam that into perfect kasan bends.

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