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Bending tubing


#1

Cynthia Tiig asks about bending 3/8" std. silver tube. Try putting a
long piece of coiled spring through the tube. This will support it
while you are bending it. To remove it, simply pull and twist the
spring (twisting it in the direction that will tighten the coils, of
course).


#2

To Alma: Making coils with a hand drill WILL be a 3-handed job. One
bends a right angle in the coiling stock, and wedges that projecting
3/8 to 1/4" in between the coil mandrel and two of the drill’s chuck
jaws. While the drill is being turned, you feed the coiling stock on
to the mandrel, in a controlled way to avoid overlaps and too much
gap between turns.

For me, clamping down an electric drill, and controlling its rotation
with a foot pedal is better. That’s just in terms of not needing a
helper, but then, I’m not terribly social either.

Dan W.


#3

Hi, I’m new to your digest but have had my fish in the gallery for a
while. I’ve been making jewelry for 25 years and have never had much
luck bending tubing, especially the larger (16mm) diamiters. Any
imput would be greatly appreciated. Thanks, Candy


#4

Someone recently posted a question about bending tubing and I have
not seen any response so I offer the following;

A piece of expansion coil spring of a size that will just slip over
the tubing will prevent the tubing from collapsing when bent and can
be slipped off after the bend is made. The coils of an expansion
spring fit tightly together when at rest whereas the coils of a more
common compression spring are seperated to allow compression under
load, thus the expansion spring works best for this purpose. Such
springs are available in an infinite range of sizes from industrial
supply houses and the local hardware store may have a few sizes in
stock.

Roland Beaver


#5
    A piece of expansion coil spring of a size that will just slip
over the tubing will prevent the tubing from collapsing when bent
and can be slipped off after the bend is made. 

Roland; I have used your method several times with fair to good
results and then I had a plumber give me a hint that he used in
bending Copper tubing into odd places and he used the spring along
with filling the tubing with very fine SAND.


#6

even more primative and simple is to use common sand. fill the
tubing, fairly tightly, with sand (possibly from a sandblaster) then
pinch or hammer the ends closed, to keep the sand in. then procede
to bend accordingly. one of my professors has shown me this process
when we created our own tubing . it worked extremely well. hope this
helps. Sara in sweaty Savannah, Ga (a lurker finds her voice>


#7

Find a size of nylon string that fits well in the tube. (Nylon
string like the stuff that fits in a Weed Whacker )I am not sure
where the hint came from - I thought it was from Orchid, but it
worked for me.


#8

I have been told that melting doping wax into the tube using a
funnel is also very effective.

Joel


#9

Plastic tubing with very thick walls comes in a variety of out side
diameters at Home Depot. I bought a foot of many of the smaller
sizes, which fit inside the tubes I want to bend. It seems to work
reasonably well to keep the tube from buckling as I bend it, using a
small spring-type tube bender. I haven’t experimented very much yet,
or compared this to other approaches.

Dian Deevey


#10

I have a job where I need to bend 14k white and yellow tubing into
rings that will be used for pendants. I need to use approximately
2.5mm (OD) medium weight tubing and bend it into rings that are
around 23mm in diameter.

I very seldom need to bend tubing for anything. When I have done it
in the past I have annealed it slipped wire (something like heavy
binding wire) into it and bent it around a mandrel by pulling the
ends of the wire. That worked without kinking the tubing but it was
smaller diameter tubing. Some have said to insert copper wire that
fits snugly and bend the tubing without worry of dents/kinks, then
dissolve the copper with acid. Maybe there is a tube coiling tool
for this that I’ve overlooked?

I have to make a bunch of these, like 40-50 and they all need to be
exactly the same, so I’m looking for a good method…maybe one to
make a coil that I can then cut like jump rings. Any ideas or
instruction will be appreciated.

Thanks,
Mark


#11

Google for a product called Cerro Tru. This is a low temp metal alloy
that can be removed by boiling in water and cleaning with a steam
cleaner. Plug the tube with a cork or wood stake and melt Cerro Tru
and fill the tube. Bend as needed and then drop in a kettle of
boiling water. After it heats up the metal will just flow out. The
residue if any can be cleaned out with steam.

Daniel Culver


#12

Hi Mark, Try this :

http://www.hitechalloys.com/hitechalloys_005.htm

Cerrobend, Bendalloy and others are low melting alloys–bismuth,
lead, tin, etc.-- that fill the tube allowing it to act as a solid
rod. The filler is then melted out in boiling water, following the
manufacturer’s instructions.

I have also used fine sand such as mason’s sand, glass blasting
beads and even water frozen into ice to bend tubing without kinking.

In any case, once your tube is filled, you can wind it like jump
rings and cut with a saw or separating disc.

When bending tube, wire, etc. I find it best to leave extra length
which allows for leverage.

Hope this helps.
Take care, Andy


#13

you might try annealing and plugging one end ends with copper, then
filling with very fine sand and plugging the other. i did this with
light weight brass tube so you’ll have to put alot more force in to
it than i did.

you could also fill the tube with a low melting alloy like wood’s or
fields metal (one of them is lead and cadmium based so you’ll have to
google them). or pure gallium would be better but its expencive. all
these metals meltin hot water and are reusable.

Hope this helps
Chris Boland


#14

Using Cerrobend sounds fine - in theory, but have you actually tried
filling a 2.5mm OD tube with it? If you can actually do it, will it
come out of a coiled tube afterwards? I seriously doubt it.

Filling the tube with copper wire doesn’t work either; I tried that
with sulphuric acid and it had no noticeable effect on the copper. I
ended up making the tube with a core of soft iron and dissolved that
away with sulphuric acid. Every time it stopped fizzing I replaced
the acid. It took a couple of days! But it did work - eventually. That
was for some white gold earrings - 2mm OD tube bent round an 8mm
former.

I made some hoop earrings from 3mm yellow gold tube wound on a 25mm
former, and managed to do that without filling the tube at all. I
made sure the tube was well annealed first, and just tried it - it
worked, but 25mm is a lot gentler than 8mm.

In both cases I made the tube myself.

Regards, Gary Wooding


#15

Hi Mark,

An automotive brake line tool might work, but it’s doubtful that the
wheels come in small enough sizes to use on 2.5mm tubing or give you
a 23mm OD. The guys at Snap-On could tell you though. An HVAC
(Heating, Ventilation and Air Conditioning) tool supplier may have
tools to make small coils. Might be worth a call or two or a Google
search to find out.

You could make something similar to a plumber’s pipe bender with an
18mm diameter aluminum, wood or even plastic disc, 2.5mm thick, and
a couple of 3/32" thick or so by 25 to 30mm diameter steel discs on
either side with a through-bolt holding the stack together, and then
held in a vise. A small screw or something near the edge could be
used as a retainer to hold the tubing in the groove and give
something to bend against. The inner disc doesn’t need to have a
rounded groove to work, but it may cause a slightly flattened inside
diameter without it. Cut about a third of the stack off so it has a
sort of “D” shape and you could probably make coils just by twisting
the tubing slightly with each 2/3 circle bend so the bent portion
just misses the straight part as it comes around. Go take a look at
a pipe bender in the plumbing section at Lowe’s or Home Depot if I’m
not making sense. You’ll get the idea.

There are also little spring doodads that go on the tubing that
prevent it from kinking, but those don’t work so well when smooth,
even, tight, circular bends are the order of the day. Those are
available from hobby shops and automotive tool suppliers. There are
tubing benders used for making model aircraft fuel lines from brass
tubing. They are simple and cheap and they work very well, but they
won’t let you bend more than about 330 degrees. You would have to
make half circles and solder them together, but it would work if
nothing else will. I’ve also heard something about packing the tubing
with sand and plugging the ends, but I’ve never tried it.

Dave Phelps


#16

Hi,

the common name for this alloy is Woods Metal. Years ago it was used
in dental labs for making patterns for false teeth once an impression
had been taken. Used in science labs as a dense filler/moulding
material.


#17

Fill the annealed tubing with water and pop it into the freezer for
a while. This is how several companies bend the thin walled tubing
for trumpets etc. and it has worked well for me on thin brass tubing
down to 1/16 inch dia. For the smaller sizes you may need to use an
hypodermic needle to fill the tube but I usually just suck the
tubing like a straw. Block one end of the tube with a bit of wax or
something similar to stop the water running out and, when you remove
the tube from the freezer, complete the bend straight away before the
ice melts. This method has the advantage that there’s no difficulty
removing wires / clean up etc., the water just melts away.

Ian
Ian W. Wright
Sheffield UK


#18

Hi Mark

I have never had any problem coiling gold tube, Silver, 9 ct or 18
ct providing the wall thickness is about 0.5+ mm for about 2,5mm. By
the way how long are the lengths? The longer the better.

Find a piece of pipe, or steel just a bit smaller than the diameter
of the ID of the rings you need to make.

Make a piece of copper wire to fit tightly just into the end of the
tube, perhaps slightly taper with a file.

As you say, first anneal the tube and test a bit, if it does not
collapse then your in business.

Insert into the tube about 15 mm and carefully bend that end around
the mandril set vertically in a vice.

Prepare a second piece of copper wire to go into the other end of
the tube. Start bending the wire and the tube. Get a friend to hold
the bent end as you carefully coil the rest of the length around the
mandril, when you reach the end just continue to coil the copper a
bit. Remove copper.

You should have a perfect coil, you may need to adjust the size a
bit, mark and cut. I use a piercing saw blade with the teeth facing
forward (as with a hack saw) cutting against the bench pin.

You can also draw down aluminium wire (welding rod) to just fit in
to the tube, all the way through, cut your rings and put in sodium
hydroxide which will eat out the aluminium.

Takeing Great Care!
jewellerydavidcruickshank.com.au


#19
even water frozen into ice to bend tubing without kinking. 

I did see a video on-line where they were manufacturing trumpets and
they did fill the large brass tubing with ice before bending, so I
know that’s a method successfully used in manufacturing. I figured if
I used that method I’d need to work super fast with a 2.5mm tube just
because it would melt right away! Although if I did it outside, here
in Wisconsin, there’d be no worry of anything melting. Maybe I’ll
combine that with Dave’s jig suggestion?

Mark


#20

Removing the insert wire can be difficult. I use stainless steel
cable as an insert into fully annealed tubing & can bend tight radii.
If the cable is hard to remove, grip it lightly ( so it can slide) in
a vise with the tubing just outside the jaws & pull the cable with a
parallel-jaw pliers or vise grip.