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Tapered thick walled tubing


#1

I wish to make a relatively thick walled tubing for a project I’m
working on. It will be made in sterling but would probably work just
as well in gold. The finished length will be 3in with a od of 5mm at
one end and 2mm at the other. Wall thickness of about.5 mm. I could
just forge it in a tapered slot with hammer and small tools but I
wonder if there are some other ideas on howto make these tubes from
stock seamless tubing. The finished product must be even from
beginning to end. Maybe some one out in orchid land could come up
with some ideas? Always love orchid! Michael S. Grace


#2

Im glad you say relatively when describing the tubing thickness. As
Id find .5mm thick as being very thin!.

Not to worry, How to make your tapered tube? well, it will depend on
how many you need, just one for example, id file it or turn it down
in my lathe out of solid, and drill out some of the excess from the
thick end with progressively smaller drills.

for anything over 2or 3 off id make up a 2 part steel tool within
which id be able to bend up a strip of the metal using a mandrel as
the final former.

Then solder up the seam.

Time is money.


#3

This is really very easy.

Firstly forget the idea of hammering a piece of tube.

Draw the cone you want to make exactly then add a couple of mm to
each end.

extend the two lines of the taper till they intersect then with a
compass draw two arcs one through the wide end of the cone extending
beyond cone on each side, equal to the wide width of the drawn cone.
Then using the compass set to the width of the long end of the cone,
mark the intersection point from each corner through the arc.

A second arc is to be drawn from the long intersection point through
the narrow end of the drawn cone.

Draw lines from the long intersection point to the large arc at the
wide end.

You now have three joined cone shapes.

Transfer the drawing to your silver sheet. If you use double sided
tape you can stick the drawing to the silver.

Now I would not use.5mm sheet, you are just giving yourself problems,
difficulty in soldering and .5mm is just too thin and liable to
distortion.

I would use 1mm.

Saw out the shape of the large cone with the extensions.

The extensions are necessary as it is is almost impossible to get an
exact cone of a required size. Therefore I prefer to waste a small
amount of silver rather than have to do the whole job again by trying
to be too exact.

File the edges straight then form the cone around a suitable
mandrill, bend the edges first with a mallet then gradually bend from
the edges to the centre, keep the edges straight / flat.

Bring the edges together so they join perfectly and solder.

File off any excess solder and mallet on a mandrill to form a
perfect cone.

File off any excess metal carefully so the base angle is as you want
it.

David Cruickshank (Australia)