Bulking problem?

Hi, I am a stick maker and am trying to make a stick out of cow horn. Typically the horn is approx 17 inches long and hollow for part of its length commencing at its widest diameter which is usually approx 60mm. It usually has a wall thickness of approx 5-10mm and it is like an onion in section in that the wall is in layers and herein lies the problem. I need to squeeze the horn in from 60mm down to 30mm and have tried conventional blocks to squeeze it down but the horn layers then de- laminate. I have been told I need to apply concentric pressure in order to prevent the horn de-laminating during the squeezing process. Believe me I have tried all sorts without success. I happened to come across an advert for Clarkson Autolock collet chucks and was wondering if this may be the solution? One of the problems would be that I need to be able to squeeze the horn along its entire length and Im not sure if this piece of kit will allow the horn to slide up and down. Also I need to be able to do it by holding the collet chuck in a vice so I can apply purchase. Any help/ ideas would be most appreciated. thanks Brian

Hello Brian,

Is is possible to make the horn material flexible? Steaming comes to mind, it is after all made of something akin to finger nails and I imagine that can be softened with heat at those temperatures.

Rather than try a collet chuck, which only closes over a small length to pull in a steel collet, I would be tempted to try a series of hose clips over the length you want to squeeze.

Regards

Brian

PS There are plenty of stick makers up here in Yorkshire, sheep horn seems to be the favoured choice and those are manipulated I feel sure.

Edited By Brian Wood on 09/08/2019 18:28:18

Clackson autolocks are definitely not the answer.

Maybe large diameter heat shrink tubing. If you get some 70mm diameter, and can get it to shrink on without slipping, then put successive layers on, the constriction is considerable. I would expect that the horn requires heating before it can change shape, and the use of a heat gun to shrink the tube would be sufficient.

Possibly, if the horn is straight, it might be possible to push it through a die made from metal with a tapered hole in it. I still think heat is required.

Try a piston clamp

Brian, that fees like a huge reductio in size to me and I do wonder if it will be possible without softening the horn first.

Could you just use a battery of Jubilee clips - if necessary they can be dipped into hot water along with the horn and by differential tightening you can adjust the fit.

I would clamp onto a suitable mandrel first and then transfer the horn to your stick once down to size.

Hi guys, Thank you for your input. I should perhaps have said in advance that prior to doing anything the horn has to be heated. I have tried using a battery of Mikalor heavy duty clips along the entire length boiling the horn and then tightening the clips. This works a treat initially and really pulls the horn in quite easily. You could also do a small section at a time using a heat gun. However when you reach a certain point and the torque increases the threads just strip on the clips. If anyone has any ideas on some form of super strong clips that will withstand the torque based on my partial success with the Mikalor clips this may work.

Not sure what a piston clamp is but I,ll look it up. Unfortunately the horn isn’t straight so I don’t think it would push through a die. Whatever the method it has to be done in small increments otherwise for sure the horn will de- laminate. A cable crimper or swagging machine has also been mooted to me but these are very expensive and I could not justify the cost. Thank you everyone for your interest

Have now had a look at piston clamp, I,m afraid no way this would work

Would drilling the diameter that you want through a length of good wood. Then cut the wood along the length so that you end up with two halves.

Heat the horn and then clamp it between the two wooden moulds.

I expect that you would need various sizes so that the horn diameter is reduced in stages.

.

Brian,

I wonder if you are using sufficient heat ?

... "It may be shaped by applying heat (a soft gas flame or by dipping in hot oil) "

Ref. **LINK**

https://heritagecrafts.org.uk/horn-working/

MichaelG.

Hi Michael, thanks for your post. With regard to heating the horn is heated in boiling hot water for a minimum of 30-40 minutes. The main problem to overcome is whatever method is applied if you apply too much force in one go the layers de- laminate it will have to be done very gradually applying pressure evenly so you do not form any kinks whilst bulking. I estimate approx 15 hours of work

old mart. Do you really think the shrinking tube would apply sufficient pressure to squeeze the horn down?

Hi my brother made shepards crooks and sticks using rams horn. The horn was boiled in water and when soft where tied to a wooden former. Left like this for a few days and the field sanded and polished. I know this is not what you asked but may just help. Arthur

Thank you Arthur, I am an experienced stick maker and have made many a rams horn stick. The rams horn is far more malleable and most importantly is not formed in layers that de- laminate when too much pressure is applied in one go. Oh if it were only so simple

.

It's a difficult concept, Brian [perhaps someone else can explain] but I believe that hot oil will transfer heat more slowly, and therefore more effectively, to the horn than would boiling water.

MichaelG.

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Edit: the explanation might be somewhere here: 

http://www.cookingforengineers.com/article/224/Heat-Transfer-and-Cooking

Edited By Michael Gilligan on 09/08/2019 22:46:14

How about trying a number of ratchet straps.

Tourniquets? With a bit of cloth padding under the ropes?

**LINK**

https://www.hornguild.org/articles-from-the-archives/heating-cow-horn-by-the-horn-swogglers/

Just thinking aloud here... I have no experience of, or knowledge about the subject, but when did that ever inhibit anyone posting to a forum?

I don't doubt the delamination phenomenon, but it seems a bit odd that a symmetrically-applied, radial compressive force causes delamination, unless there are severe axial shear forces at work. In other words, the inner layers are being squeezed, orange-pip-like, towards the open end of the horn. Perhaps the horn also needs to be constrained axially, having given the wide end a plane bearing surface, so all layers can be supported, as the radial force is applied.

Alternatively, although I'd expect high shear forces to be induced, another way of squashing down the horn may be to try drawing it down through a succession of smaller diameter dies, as in wire drawing. Perhaps many small diametrical reductions between heats might avoid delamination. I would imagine that the horn might need to be soaking in whatever heating method used for perhaps tens of minutes, to make sure it's 'cooked' all the way through.

Another way of applying surprisingly large forces is by wrapping with strips of well-stretched rubber (eg strip cut from old inner tube), perhaps several layers.

Look up Horn Swogglers on Google, toward the end of that you may find something.

Ian S C

Ditto.

I'd guess this is an old technique and that implies a low tech solution? How about wrapping in wet leather and then unwrapping the large end after a shrink cycle while rewrapping with fresh wet leather - guessing that'd give more compression than stretched inner tube?

As another thought put inside a chinese finger trap and crank that longer using successive sizes of traps??

pgk