How to bend hollow

Jewelry Discussion
1

Hello

i have hollow tube i need to bend to make round bangles.

tube diameter=10 mm
thickness of tube=0.7mm
bangle bracelet diameter=65 mm

what is the best way to make bending is there any special equipment?

thks again for your insights
best
nathalie

2

The classic “old school” technique is to plug one end of the tubing,
fill it with water, freeze it, and bend the tube full of ice.
Depending on how intricate your bends are, one of the small spring
bender tools sold at hardware stores may be helpful.

The whole point is, once filled with ice, as long as you don’t get
brutal, you are dealing with a solid wire for all intents and
purposes.

There’s a lot of ways to do this, especially with a good size tube
like 10mm.

Ron Charlotte – Gainesville, FL

3

a spring type bender would work well - but with any hollow tubing you
must be careful- filling it with wax or wet sand can be useful as an
experiment. i would use sand over wax first time as even wax requires
some skill…and by wax I mean sealing wax: beeswax and plaster mixed,
or straight beeswax…paraffin can crack particularly if you try it
with a candle stub that has had stearates added…for some reason its
inferior to the others, and carving waxes are too expensive…Again,
wet sand is the recommendation , or fill the tube with wet sand and
form carefully.You can buy tubing benders at any harbour freight, or
hardware selling hand tools or home stores…usually the spring type
comes in a set of three small diameter lengths.It too has a learning
curve if you haven’t used them before- so try with some recycled
copper tubing matching the gauge and diameter as closely as possible.
or at least, fire coat and anneal then put your tubing in the bender
and go for it…rer

4

Nathalie

I haven’t done tube that size but this is what I do with smaller
tube. first anneal then solder a piece of scrap on one end… fill
with fine sand or salt…tamp in the material to pack tight… I put
the sealed end in the ultrasonic it packed the material very
tight… seal the open end with bees wax… I then used a plumbers
tube bender they come in all sizes and a mandrel and bent the tube
around it… I have even gotten some nice s curves this way HTH

Robin

5 
i have hollow tube i need to bend to make round bangles...

It’s really pretty easy Nathalie. There are a few ways to do it,
I’ll give a couple of suggestions. With any of them you’ll want to
anneal your tube first. And you’ll need a dowel or mandrel that is
slightly smaller in diameter than your finished bangle. The tube
will need to be 2.5 to 3 inches longer to allow for the ends that
won’t make the curve perfectly.

I think the easiest way is to clamp you “dowel” in a vise vertically.
Then clamp the end of the tube onto the dowel with a vise grip so it
is perpendicular to the dowel. Set the edge of the vise grip so it
flush with the edge of the tube on the side you intend to coil
(usually the up side) so you can coil tightly. Then using your hands,
coil the tube around the dowel while being careful to apply even and
continuous pressure, close to the dowel, so you don’t create a kink.
You should be able to coil it around the dowel fairly tightly except
for the last little bit. When you’re finished it will spring open a
little bit, that’s why you need to dowel to be smaller than the
finished diameter. Release the clamp, check your diameter, pull it up
a mandrel if too small, and cut it like you’re making a giant jump
ring.

An alternative is to pinch one end shut and fill the tube with fine
salt, then stuff the other end with wax. The idea is to help prevent
denting or kinking. But in practice, I’ve never had an empty tube
dent or kink. A tip would be to buy some brass tubing as close to the
size you need at a hardware store and practice with that before you
use your tube, this will also help you determine the diameter the
dowel or mandrel needs to be. If you need several bangles, just buy
an extra-long tube and make a bigger coil.

Good luck,
Mark

6

Here are a couple of links that show the best way i have seen yet to
make coiled tubing.

http://www.ganoksin.com/gnkurl/13r

Thanks,
Aaron

7 
I haven't done tube that size but this is what I do with smaller
tube. first anneal then solder a piece of scrap on one end... fill
with fine sand or salt...tamp in the material to pack tight... I
put the sealed end in the ultrasonic it packed the material very
tight..... seal the open end with bees wax...

This is an excellent post. May be there has to be some kind of an
award for good posts.

A lot of times people give suggestions on how to do certain things in
a form that my teacher called “rhinoceros stew”. How does one make
rhinoceros stew - first catch live rhino and. And of course details
of how to catch live rhino are always omitted.

Bending large diameter tubing is not easy, simply because surface
areas of the inside and outside are different and the larger the
diameter, the greater the difference. At some point it exceeds the
ability of metal to absorb this difference via
stretching/compression. The preparatory details like packing the
send, providing seals that can withstand forces which develops during
bending are critical to the success. If they are missing it, than
methodology simply becomes a rhinoceros stew.

Leonid Surpin