I checked and I cannot find were I ever posted this, so here it is, it may be common knowledge in the horn world.
It is a little jig to help guide the die while threading horn tips and to put external threads on horns. It can be made from either a ½-13 bolt and a 5/16-18 bolt or a 5/8ths-11 and a 5/16-18. I have them made up in 4 different configurations and use different ones based on the size of the horn/tip and style of horn, the two above and 1/2-13 with a ¼-20 and 5/8-11 with a ¼-20.
I am going to talk ½-13 with 5/16-18 here. Start by cutting the heads off both bolts, next cut the ½” to about 1 ¼” long and the 5/16 to about ¾”. Put the 5/8s in a chuck and drill for a 5/16-18 tap. Drill in about ½” then tap, leave it in the chuck and put the tap in the Jacobs chuck and start it by hand, once started put the tap in a tap wrench and finish it off, lube, lube, lube. Try the 15/16 in it, you only need about 3/8 to ½” sticking out.
To use it, drill the tip, ¼”, put it on a Pen mandrel and rough turn it, leave it as large as possible, turn the step where the threads will be, make it longer than you need and taper it slightly so the die will start easier. Take the tip off the mandrel and tap with the 15/16-18, since the hole is only 1/4” you will have to counter bore about 3/4”, be careful, lube, don’t force it or it will crack. Screw the jig into it and start a ½-13 die on the bolt, use lube, turn the die down and if you tapered the step enough it(die) should start cutting, Lube, put the die in a vice and using a pipe wrench turn the tip down into it. Go slow, ½ to ¾ turn, back off and repeat until the die bottoms out. Slowly unscrew the tip and jig from the die, clean out the die, turn it over and repeat, it should turn down about one full turn more.
Screw a nut on to it a couple of times, it will burnish the threads some. File it to length and round over the upper threads so it will start easier. If you have you horn threaded try it and see what you’ve got, don’t force it. If it does not screw all the way down put it back on the mandrel and with a parting tool make a shallow cut at the end of the threads where the step is. Take a counter sink and open up the hole in the horn just a little, do it with counter sink between your fingers. Try it again and if necessary put it back on the mandrel and take a little more off, continue until the two pieces fit together with no space.
Then back on the lathe and final shape.
To use it for external threads the procedure is pretty much the same. Drill the spout hole and thread it for whatever jig size you are going to use. Turn, file or use a hole drill to get the threaded area ready, still use a taper. Screw the jig in, lube and thread, turn the die around and run it back down and your done.
Tim C.
Note:
The dies need to be either new or have very little if any use on metal, you want them as sharp as possible.
