Hi,
I’m looking for some instructions on how to make a threaded,
screw-on cap (I’ll be using sterling silver). Does anyone have any
suggested resources or a tutorial they could recommend?
Thanks,
Beth
Beth Taylor
The obvious way to make a threaded cap is to use tap and die, or turn
threads on a lathe. The problem with tap and die is that it doesn’t
work, or work very well, on sheet metal - it deforms it before the
threads are cut. But, if it’s viable for you, that’s the best and
easiest way - maybe even a pipe tap. You can make a solid part for
the male threads and then drill it after, and make a stout part for
the female and then take down the outside after to avoid the
deformation. The old-fashioned way to make cap threads is with wire.
Get a mandrel of the SAME size as your cap - even use the mandrel to
make the cap. Get two pieces of silver wire, maybe 18 ga. or so. I put
the ends of the wire against the mandrel and clamp it all in a vise.
Then wrap the two wires around the mandrel as though you were making
jump rings. When it’s long enough and some extra, unclamp it,
carefully take the two wires apart, solder one coil on the inside, one
on the outside, maybe file a little to adjust and voila’ - threads.
I'm looking for some instructions on how to make a threaded, screw-on cap (I'll be using sterling silver). Does anyone have any suggested resources or a tutorial they could recommend?
You could find a tap and die set that’s the correct size. Or, for a
completely handmade look, you can use two lengths of same-gauge
wire, wrapping them side-by-side around a non-tapered mandrel of the
desired size.
Wrap almost horizontally around the mandrel for best results (the
angle determines the pitch of the threads). Once you’ve got it tight
and uniform, slide off the mandrel, and gently separate (unscrew) the
two wires. Now you’ve got a pair of wires which will thread into one
another…one to become the outside threads on the cap, and the other
to be the inside threads in the vessel. This will yield a set of
“acme”-type threads.
Matthew Crawford
www.MatthewDesigns.com
Hi Beth;
I'm looking for some instructions on how to make a threaded, screw-on cap (I'll be using sterling silver).
There is a way to fabricate one of these, I think Charles
Lewton-Brain had shown a method, but I don’t know if it’s in any of
his books. I have another way you could try. Find a plastic container
with a screw on top, as in a toothpaste tube and cap, or a small
plastic bottle, etc. You cut off the male threaded part, and sprue up
that and the cap and burn them out and cast them. Fabricating them
involves wrapping a double piece of wire around a mandrel and then
unscrewing them into two separate coils. You then need two tubes, one
with an inside diameter that the coil will slip into, the other with
an outside diameter that a coil slip over. But the wire thickness has
to just make up the difference. The coils are soldered onto their
respective tubes, and the larger tube capped off. You calculate the
sizes by finding a pair of tubes first, one with an inside diameter
about a millimeter or two larger than the outside diameter of the
other. When you find two tubes appropriately related as such, and
which are pretty much the size of the cap you’re interested in
making, then you use wire that will, when wrapped around the smaller
tube, fill the distance between the two. Clear as mud, right?
Hopefully, someone on this forum will have a reference with
illustrations and better explanation.
David L. Huffman
In Tim McCreight’s “The Complete Metalsmith, Revised Edition, 1991”
page 152. This page has descriptions and a couple of excellant
drawing of both partial and full treaded closures. I’ve tried both
with fair results my first time, T.M. is a gifted remote instructor.
Ed
One trick that should not be overlooked for producing an internal
thread, where strength and critical fit are not an issue, is…
Starting with the cap which fits “loosely” over the existing male
thread, wrap the male thread with a bit of wire which then fits
snugly inside the cap; then carefully unscrew the wire and solder in
inside the cap. Voila, you have created a threaded cap!
Regards to all,
Dr. Mac