Any suggestions for bending S.S. tubing in a radius. I
have a 25mm long 5mm o.d. piece of tubing I am trying to
bend in a smooth curve.
I have tried heating and pushing/pulling with less than
desirable results. Tried inserting a brass brazing rod of
same inside dimension and heating while gently bending,
hoping for a smooth bend. Of course, the brass bends long
before the silver then the tubing cracks and becomes two
pieces, not what I had in mind.
First, anneal your tubing completely, allow to air cool slowly
and insert the brass rod. Bend around your mandrel and you
should find you get a smooth arc without any cracking. Most
stock is shipped semi-hardened and must be annealed before
working.
Try wrapping wire tightly around the tubing before you try to
bend it. Make sure you wrap it closely, each turn right up
against the previous one. Copper wire will do.
There are springs that you can slip over a piece of copper
tubing when you bend it for plumbing, same principle.
To bend the tubing use a tube bending spring, or other spring
that fits perfectly inside the tubing. This will force it to
maintain its shape while bending.
Lisa Krikawa
it’s sunny and warm in southern Arizona, too. Aren’t we lucky?
You have 25 mm of 5 mm tubing and want it bent into a smooth
curve…very difficult to do. A short piece like that affords no
leverege for bending and as you know, tubing will kink and fold
just like a drinking straw, rather than bend smoothly, the way
you want it.
I have heard of people filling tubing with a variety of things,
sand, clay, ice, etc. but my own efforts in those directions did
not work satisfactorily.
Here is what works: Take a piece of the silver tubing much longer
than you need. Anneal the silver tubing. Go to a hardware store
and find a large spring that fits snugly around it. (Check out
the kind used to close a screen door.) , With the spring around
it, bend the tubing and spring against something like a baseball
bat. If you have enough material you can apply force with
leverege. The spring will keep the tube from collapsing and the
bat will guide the curve. After bending, slip the spring off to
reveal gently and evenly curved tubing.
Good luck.
Alan Revere
Revere Academy of Jewelry Arts
San Francisco
Thanks to all that responded to my request for assistance.
I got the bend I was looking for by annealing the tubing, then
packing the tubing with corn meal, then bending around a cable
thimble. The thimble had just the right groove to fit the tubing.
It bent smoothly without crimping.
Tim: It is sunny and warm here in Northwest Iowa also. But I bet
your warm is warmer than my warm.
Try using a steel tension spring with an ID the same as the OD
of your silver tubing. A set of differant sized springs can be
obtained from hobby shops for tube bending. I found my set in a
hobby shop specializing in model railroading.
Try filling the tube w/ either pitch, a dense wax, sand or ice.
Stop up one end and fill w/ water, leaving room for expansion,
and freeze. Pitch , wax or sand will probably give the best
results…
There’s a product called Cerrobend which trumpet makers use to
fill brass for bending. i think it’s a low fusing metal type
product that can be boiled out of the piece once bent.
Joanie, I’ve had success in bending small diameter silver tubing
by wrapping the anealed tubing tightly with 18-20guage binding
wire. Lubricate the silver with wax or oil before binding then
gently, by hand, form over a curve that is slightly smaller than
the curve desired. If you are trying to bend the tubing into a
very tight curve, say for a ring, you will have to slip the coil
off and anneal the silver once or twice before completing your
bend. I discovered this technique at the hardware store. Large
coiled springs are used by plumbers to bend copper tubing of
various diameters. Have fun! Gina Pankowski, Lattis Design @gpankowski
Tim, how far does it need to bend? In a complete circle? If you
just need a bend, insert a solid brass or copper wire and bend
the (annealed) tube cold. If it needs to bend into a complete
circle, you need to saw slits on one side of the tubing to remove
material from what will become the inside curve of the circle. Go
to an auto parts store and pick up “tubing benders”, which is a
tightly spiraled tube with a bell flare on one end. Insert your
tube into the tubing bender, make sure your slits are aligned
correctly, and gently work the bend. After bending, remove the
bender. Align the ends together which need to be soldered. Solder
the ends and run the solder along the slits (wire solder is best
for this) to fill them in. Hope this helps.
Hi Tim, I think I once read Oppis book (?) or perhaps in some
other valuable source, that you could fill the item you want to
bend with lead (Pb). First anneal/quench then fill your tube with
lead (lower melting temperature that Silver). Heat the whole
stuff so that it will fill with the melted lead. Let it cool and
bend.
Heat the whole thing beyond the lead melting point and let the
lead flow out of your bended tube. How you get melted lead into a
5 mm tube - that’s something you have to figure out by yourself
There are probably better ways than this one and I’m sure you’ll
get some interesting suggestions - will you tell us how you
eventually made it?
Any suggestions for bending S.S. tubing in a radius. I
have a 25mm long 5mm o.d. piece of tubing I am trying to
bend in a smooth curve.
G’day; You could try filling a slightly longer length of very
well annealed tube with a very fine sand - or even fine salt.
Crimp the two ends and bend carefully and slowly over a mandrel.
The difficulty is that when a rod or tube is bent, the inner
side of the curve is under compression and the outer part is
under tension - the stretched and compressed metal has to go
somewhere, and unless the tube has a content of liquid-like fine
and almost incompressible material, it will collapse. If you try
to bend tube with a solid rod or wire inside, it will tighten
over the solid rod and thus the inner rod will be almost
impossible to remove - other than dissolving out. And that’s not
easy either. I suggest you try fine table salt, and don’t forget
the tube must first be thoroughly annealed. You may have to
make a longer piece of tube than you need in order to give you a
little leverage, and cut it to size after bending. Cheers, and
let us know how it goes. –
Any suggestions for bending S.S. tubing in a radius. I have a
25mm long 5mm o.d. piece of tubing I am trying to bend in a
smooth curve. Hi,
I have used the following in bending tubing:
After the tubing is annealed…
Fill the tubing with melted beeswax before beginning the
bend. After bending, remelt in boiling water to remove wax.
I have also used fine sand sealing it in with tape at both
ends of the tube.
Also, you can use fine silver wire or a tube of smaller
diameter. I use 3 -n-1 oil to lubricate the wire or tube to add
ease in removing.
I usually bend the tubing with my hands around a jig or mandrel
to help with the bend using a soft binding wire to protect the
tubing against scarring, or just my hands depending on the
effect I am looking for…I have seen others use a wood shaping
block that is grooved to help with the bend.
I joined in late on this subject - so if my question sounds half
baked it is because I haven’t read some of the other emails on
this subject- Steve, in regard to bending sterling silver tube
wire- how do you get the brass rod out of the tube after you bend
it? It seems like you would be adding a lot of unnnecessary
weight to a piece leaving it in.
Dear Tim - I’ve filled gold tubing with water soluble wax using
a wax injector. I then put one end in a vice and crimp the other
end between a heavy piece of pipe of the diameter I need for
the bend and a vise-grip plier. It can be hard to get the bend
started without a crimp - keeping the tubing under tension by
pulling as you turn helps. This does a pretty good job although
the tubing does flatten a little bit. I then saw the coil into
the lengths I need with the wax in place and disolve the wax out
in hot water.
there are commercial devices available for bending tubing such
as a spring that fits over the tube but I’ve not found them to
work for my needs.
Micro-Mark used to carry a tube bender . It consisted of a
series of different size coil springs each about 4 inches long
into which various sizes of tubing could be inserted and gently
bent without being ruined.
Bending silver tube is no problem with the right tools. The
supply for the tools is another matter. MAC AND SNAP-ON
automobile tool suppliers have a tube binding kit that has the
spring tools for bending in assorted sizes. Suppliers can be
found in your yellow pages of most cities. If MAC or SNAP-ON is
not in your area try a major auto parts store in your area. Be
sure to anneal the silver. If you do not do this step the best
tools will not help much.
If you can’t find the correct size spring to slide a spring over
a tube to prevent it from kinking when forming into a curve or
circle, why not make your own.
Making the spring is quite easy.
Place the tube that’s to be formed in the jaws of a
flexshaft hand piece or drill chuck.
Depending on the diameter of the tubing, start at the chuck
end & wrap 18 or 20 ga wire around the tubing for a distance at
least twice as long as the portion of the tube that will be
formed. Copper or steel wire can be used. When winding the wire
on the tube, keep the coil tight, each wrap should touch the one
before it.
When a suitable length has been wound, cut the wire supply
from the coil.
Remove the coil from the tubing. It may be necessary to twist
the coil in a direction opposite to the direction in which it was
wound to get enough clearance for the coil to slide off the tube.
Remove the tube from the chuck.
Mark the position on the tube where the forming will be done.
Slide the coil on the tube so the center of the coil is over
the center of the area to be formed.
Form the coil enclosed tube in the shape & manner selected.
After the tube has been completely formed, remove the coil.
One end may have to be held while the other end is twisted in a
direction opposite the winding direction. Adding a little
lubricant ( liquid soap etc.) to the tube before installing the
coil may help with coil removal.
Mark the coil with the diameter tubing it was used on & save
for the next forming operation. Before you know it, you’ll have a
good selection of tubing forming springs.
FWIW: When things are bent, it’s an accident. When things are
formed it’s intentional & by design.
