Further ideas on flattening/processing?

[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.

[bownarra]

Yes there is a whole load of nonsense written on the subject of hornbows….even more so than with wooden bows.
You are asking too much of the horn if it won't bend after steaming. Nothing will work.
There is a reason the rounded core/horn was used traditionally
Balau is not particulary reseptive to glue, is too dense and oily. Massa ia definite no no for the same reasons.
The properties of a core wood should be excellent gluing properties,medium density 0.60s.g., easy to steam bend and diffuse porous for a more homogenous material. Hard maple is perfect.

[MattZA]

It's just so strange that some horn will happily bend like it's made of rubber, yet others won't give an inch.

I would use a convex core, but unfortunately it's already flat... Also, I wouldn't have the first clue how to make a convex core match up to a concave horn. I'd end up with gaps 1/4" big!

How much horn width/thickness do you think I need for the bow? It's going to be between 44 and 46" (depending on if I decide to shorten the siyah length). Turkish design. Aiming for 50# from 29". I reckon if I filed these horn quarters into almost rectangular strips, I could cover about 7/8" of width for the handle and working section of the limbs. That would feather out to zero at the end of the kasan. Horn thickness would be in between 1/8" and 3/16".

My bamboo core is 3/16" thick in the working limb. Strange you say that Massa doesn't accept glue. I've found it fine when gluing bamboo as a backing for an ELB.

Hope you don't mind me bombarding you with all these questions!

[bownarra]

I said it doesn't accept collagen glues well not modern glues. Of course with modern glues and their incredible wetting capabilities anything can be glued but we are talking about collagen based glues for a hornbow. Trust me you definitely do not want to be using massa, even if it glued well with collagen glues it won't steam bend particularly well and is far too dense.
You are probably too narrow. I wouldn't like to go narrower than 30mm. As stability will become an issue. This is the problem with Gemsbok and why water buffalo are the preferred horns. Good usable width and length. It is also on the thin side, not too thin yet but not far off being too thin.
You get two scrapers that match. One convex one concave. 'Gaps' aren't really an issue if you use non matching grooves.

[MattZA]

For some reason I only saw this response now.

As you say, I've also only had mediocre results with bending massa. Inconsistent is probably an even better word, as I've had the occasional piece that bends nicely, but that's very much the exception.

I trust that you're right about the horn probably being too narrow as well. I'm going to give it a go purely as an experimental learning curve, but my next one will definitely have a concave/convex joint. I'm hoping that my width will be sufficient for at least 40# at 29" while remaining stable. I'll take a look at it before sinewing and make a judgement call. I've kept the siyah length at just under 4", so hopefully that'll assist stability.

Do you have Adam Karpowicz's book? I'd love to get a copy, but my school teacher's salary and the extremely unfavourable exchange rate makes it something well beyond my means, sadly.

[DC]

You can get the electronic version. I know it's a poor second but it's affordable and instant. It's a good read but I found the information is rather spread out.

[MattZA]

Ha ha, DC I was referring to the electronic version

Importing things around here is crazy. I can get a Gemsbok horn for under $6, but an electronic book sets me back $30.

I'll have to save up! I'm building based on instinct at the moment. Got my kasan and siyah shapes steamed last night. Splices all cut in. Now it's just to glue them in and then give this horn gluing business a shot in the dark. Here's hoping!

[Ed Brooks]

I had read about flattening cow horn for a powder horn, by boiling in oil, they said it was better than boiling in water. Hope this helps you out. Ed