How to clamp a powder horn for filing?

[Whiterabbit]

Not sure if it belongs here or special projects, figured I'll get more eyeballs here.

I have a couple crappy powder horns (bad trade show purchases) that I'd like to breathe some life into for backup purposes. Part of that is thinning the tips for aesthetic reasons. I want to file octagonal tapering flats in the horn.

So, actually, I already did this on one horn. it was difficult and required awkward holds trying to manipulate a file and horn together. The result is something that looks perfectly serviceable from 12-18 inches away and farther, but look real close and it's not exactly fine work.

I'd like to improve that to a good 6-8 inches away and it looks great. To do this I need to "fixture" the horn so I can get two hands on the file.

I can't just put it in a soft vise, the horn is too "plyable". so how do you clamp this thing for filing?

[pietro]

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I would suggest shaping one end of a piece of foot-long scrap 2"x4" pine so that it fit the inside of the horn, before clamping the assembly for filing.


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[Whiterabbit]

So, it was bought as a functional horn, so it's already been capped (I do not want to uncap it) and drilled.

[Omnivore]

Take a look at how Scott and Cathy Sibley do it. No clamps. I've done a few horns, no clamping. You learn to live with it. You have to be constantly moving the horn around anyway. A clamping system would bring as many negatives with it as positives, I believe.

Now there is a way to help out a lot, if you're only one person. Make a short dowel with a fairly obtuse taper on it, such that it sticks into he spout end on the horn. You don't want it to fit the spout stopper taper, because you want it to be very free to move around. Put the dowel in a vice, or fit into a hole in the edge of your workbench, etc. You place the large end of the horn against your body, keeping pressure on it, so it stays against the dowel. Now it's held between your body and the dowel. That gives you two hands free to do whatever you need to do on the horn. You can do similarly by holding a large plug in the vice over which you place the large end of the horn, keeping the spout end against your body. That's as far as I've ever gone for "rigidity", and it works fairly well! although there are still some awkward positions.

A variation on the latter is a temporary end plug with a large bolt in the center. The end plug (this could be one of your sizing plugs) fits tight into the large end of the horn, and the bolt goes onto a vice. Now you can spin the horn around on the end plug, and shove it on hard for some near-rigid holding. Use your imagination. It ain't rocket surgery.

So one of the last things you'll be doing is permanently attaching the end plug.

Still, most filing will be done with the horn in one hand, against a leather bag or a padded bench, and the file in the other hand. Keeping the horn free to move "fluidly" as you're filing is often very much preferable to having the horn locked up rigid, being that you're making curved surfaces practically 100% of the time. Even the so-called flats of an octagonal neck are on a curve of course.

[bubba.50]

clamp a short piece of broomstick or some such in a large vise, cut a hole in a piece of thick soft leather or scrap of rug or somethin' & slide over this. you can then hold the horn against this with one hand & file with the other & move it to any angle/position needed. this is from the aforementioned Sibley's book by the way.

[Whiterabbit]

Omnivore. Brilliant. Thank you!

[fouronesix]

Since the horn is a tapered spiral of sorts it's kind of tricky to clamp in a vice and work around the circumference at the same angle. Being tapered, they also don't clamp well anyway. A well padded (like thick wraps of cloth like old socks) in a pipe vice works very well. You really can't clamp a horn in tight without risking crushing it, so clamp only tight enough to resist the friction of the file. You can even use a freestanding support for the horn spout tip to stabilize the horn body held in the vice.

The problem with holding in one hand and filing with the other while resting the horn in a padded bed is that the filing angles will be tough to maintain.

I've done several and the best advice is go slow and check often so that the lines of the filing follow the general lines of the tapered spiral of the horn and the facets of the flats (if faceting the tip section) are even and geometrically similar.

[Ballistics in Scotland]

Buy the cheaper sort of large ornamental candle, melt it, and cast a rectangular piece of wood, easily gripped in a vice, inside the horn.

[wyofool]

Not knowing any better, I'd clamp the file and hold the horn.

[Whiterabbit]

Tried that, doesn't work.

[country gent]

Wrap inside of a screw type hose clamp with a strip of rubber and try clamping that around horn. then clamp the boss of the hose clamp in the vise. This should give 100% clamp pressure evenly around horn. You still will need to be carefull with tension on horn. The horns I have made I fitted a block into before plug was glued / tacked in place. Another point is dont file but use a scraper. A piece of banding with the edge sharpened can e used to scrap or peel fine amounts off very presicly. My personal horn scrapped to finish inside and out came out clear enough to see the powder level inside. For me scraping works better then files or sanding.

[GREENCOUNTYPETE]

if you take a saw horse you can slap together a saw hoarse from scrap wood , cut a slot in the top all the way through feed a belt up and back down through and use the holes for the adjustment and screws to sandwich it between 2 other pieces of scrap wood positions so that they make a pedal

place the horn in the loop step down on the pedal and it will be a strap vise

if you don't have the leather belt around , any car shop should be changing a serpentine belt on a car about every day the use one should work

[Ballistics in Scotland]

Just filing octagonal flats should be a fairly quick job. You could take a large plastic food container, make a hole in the top for the tip of the horn to stick out, and freeze it in a block of ice. Only I would file it then, because I don't think cold horn would scrape and peel so well. If the container was rectangular you would have the sides to act as a guide, and the easiest way to make a true octagon is to make a true square first.

Ice will be much stronger and thaw a lot more slowly if you mix the water with about 14% sawdust or wood pulp. This is how they made pykrete, a material with which it was proposed to build a vast, torpedo-proof mid-Atlantic aircraft carrier for heavy bombers in wartime. Lord Mountbatten of Combined Operations was an early convert, and in a demonstration drew a revolver and fired at a large block, which was virtually undamaged. The bullet ricocheted and hit the American Admiral King in the leg, but he was extremely good about it. Perhaps fortunately the Battle of the Atlantic was won by other means while it was still in development.

[gnoahhh]

I've done a couple dozen horns now and have always just held the horn in my left hand, across my leg, and free handed the files. An eye for form and proportions is the most important tool. I scrimshaw my horns by holding them on a sand bag, which come to think of it would be handy for filing too.

[Ballistics in Scotland]

If you drill a tapered hole to fit the horn in a piece of wood (e.g. with a large Morse taper reamer), and then plane away the wood until it intrudes on the hole, you have a filing guide. Clamp that in the vice and you can hold the horn in it with one hand and file with the other, the turn it to do the other flats.

[bubba.50]

some of y'all are goin' to a lot of ''Rube Goldberg'' trouble to complicate a very simple problem.