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Bending Tubing


#1

Hi - Does anyone know where to find the thread on bending tubing in the
archives? I made a pretty thorough check and couldn’t find it. Has
anyone worked with Cerro Bend? We found the product through the
Thomas Register and have ordered some to experiment with. I’m helping
a friend who is trying to bend 3/8" sterling tubing (and 1/4") - a
right angle bend and about 3" long. Copper bends pretty readily -
sterling is another story. Thanks ahead. Cynthia


#2

What are the wall thickness’? The intended bend radius off the
tube center line?

If you are having trouble, these are the first questions. Jesse


#3

Cynthia, Are you trying to bend the tubing in a 90-degree arc 3" long,
or put a true right angle bend in a piece of tubing 3" long (e.g.,
L-shape)? Have you tried annealing the tubing to make it softer?
You might want to look at a tubing bender used to bend automotive
brake lines. Warm Regards, Shawn


#4

Dear Cynthia,

Cerro Bend is a lead like metal used for metal mold making. This is
in a family of lead type metals that melt in the 160 to 300 degree
range. They are not what you are looking for if your thing about some
kind of bending helper. They are all Cerro named. Cerro bend, Cerro
true etc.

I can give you a great tip on tube bending though. Call up Micro-mark
at 800 225-1066 at get a catalog. Their web address is
http://www.micromark.com. On page 39 of their Late Winter catalog they
sell “no-kink benders for small tubing”. These are small spring coils
you fit around your tube before you try to bend. After you’re done,
they just slide off. Another great part is that they only cost $4.95

Godd Luck,
Todd Hawkinson,
TR the Teacher


#5

Cynthia: I’ve tried all sorts of methods to bend tubing, but the one
that seems to work best for me is simply to wrap a spring around it
and bend it. If you can find a spring that fits perfectly, just
slide the tubing inside. If you can’t find one already made, they’re
not that hard to make yourself, and you will always have the tight
size handy. The coils of the spring will stop the tubing walls from
bowing at the sides of the bend.

I’ve made hoops like this, with heavy wall and thin wall tubing, in
both silver and gold. Remember that you will have to remove the
tubing from inside the spring, so resist the temptation to coil your
hoops like you would jump rings…

You mentioned making a right angle bend…that sounds like a
notch-and-fold project.

Doug Zaruba


#6

Doug, in your response to making your own springs for bending tubing,
can you elaborate on that aspect a bit. Thankyou, Bill Navran


#7

Cynthia,

Bending tubing with Cerro bend, or any of the other very low melting
white metals, works just fine. Other fillers I’ve used with success
at various times are fine sand, pitch, aluminum or copper wire (the
tube drawn down onto it so it’s tight, removed later with appropriate
etchants.) But remember that your success bending tubing depends a
lot on the tube itself, not just the filler you use to keep it from
crimping or flattening too much. The thicker the wall thickness of
the tube, the better it will bend. Most commercially sold sterling
(or gold) tube is quite a lot thinner in wall thickness than the
copper tubing sold for plumbing use, which bends easily. Sterling is
also harder than pure copper. Make sure its fully annealed before
trying to bend it. If the tube is too thin in wall thickness, you’re
risking tearing it on the outside radius of the bend, or buckling it,
even with a filler, on the inside radius. If it’s tube you’ve made
yourself, it will bend a lot better if the seam is soldered, or
barring that, on the inside or ouside radius, instead of the side.

Hope this helps.
Peter Rowe


#8

Sure, Bill. If you wish to make a spring, start with some steel
wire-usually sold as “spring steel” in the catalogs. Anneal it, then
coil it around a mandrel of the appropriate diameter. Once you have
coiled your spring, you will need to temper it. I prefer a kiln, but
it is possible to use a torch. That’s all there is to it. I have
steel mandrels in many sizes, and it doesn’t take long to create an
inventory of springs.

If you need some steel in a hurry, guitar strings (the straight steel
ones) work perfectly. Just a little more expensive. Ask your
guitarist friends to save you a couple if broken springs.

Doug

PS: be sure to make some springs in tiny sizes…they’re great to use
in mechanisms.


#9

I have had success in the past threading a wire through the tube and
bending over a mandrel by pulling on the ends of the wire. No kinks.
Mark P.


#10

Hi Cynthia… Try this: Get thee to a hardware store, and find a long
steel spring, just a little bit larger that the tubing that you want
to bend. Anneal the tube well, and slide it inside of the spring.
Carefully bend the spring with the tube inside of it, and don’t bend
it all at once if the bend is severe. You may need to anneal more than
once. The coils of the spring act to apply pressure evenly around the
tube, and thus the tube is less likely to buckle or dent. After the
bend has been achieved, the spring should slide off easily, and if it
doesn’t, it can be snipped off with a pair of metal shears. I forgot
to mention this when the favorite tips was threading about a while
back…how remiss…50 lashes with a wet noodle! This has worked for
me, hope it works for you. :slight_smile:

Lisa, (Back from the Cow Palace Show, (ick), where I saw plenty of
Orchidians…now I am all showed out! Desperately need to hop on the
horse tomorrow), Topanga, CA USA


#11

Hi - Thanks again for all the input. Yes, it is an “L” curve on a 1"
radius. Bending on a 3" radius - more gradual curve - worked fine.
The clincher must be the thickness of the walls of the sterling. The
walls of the copper are thicker. The person I’m helping out has tried
almost all the methods - sand, pitch, spring coils. She settled for
making castings made from the copper tubing that bent successfully.
She split the tubing in half and had rubber molds made - and then
joined the wax and had them cast. The castings were fine - a fair
amount of clean up and wax time. Personally, I hadn’t given up on the
bending of the clean tubing. Making cuts would be the next best step.
I think the Cerro Bend has a lead content - so, it no doubt has its
limitations. I believe it is used in the making of wind instruments.
It may be more useful with sculptural purposes - but I’ll be happy to
check in later after doing some experiments (the material hasn’t
arrived yet). You know - I knew there was a use for the banjo steel
strings that I keep breaking! It is always good to hang onto these
odd things. They are pretty thin though. Are the thinner strings good
to use - or is it better to use the guitar steel strings that are
coiled? Appreciate the feedback as always. :slight_smile:
Cynthia


#12

Cynthia, Speaking of hanging on to old things. If you have the old
"egg beater" type of hand drill, it is excellent for making the coils.
Many are used in the wire worker area to create necklaces and beads.
Fiskars has even produced a similar device.

If it is not in the garage left over from dad or even granddad’s tool
box, check flea markets and garage sales.

Teresa


#13

Hi Teresa. I too hang on to everything and therefore have an old egg
beater style drill. You suggest using it to make wire coils. Sounds
great. Can you give specifics on how to do this. Do you clamp the
drill handle in a vise to hold it? Also, how do you wrap the wire
into a coil. Thanks for your suggestions. Alma


#14

Hi–I don’t know whether someone has mentioned this- but Micro-Mark
has a set of “No-Kink Benders " for small tubing for 4.95. They
describe it as “Spring-type benders with a funnel end” can bend 1/16;
3/32; 1/8; 5/32 and 3/16” outside diameters. They are nickel plated
steel, and are suggested for use with brass, copper and aluminum
tubing. I imagine they could be used also with well annealed
sterling, or fine silver tubing. Their site is http://www.micromark.com.


#15

Alma, The mandrel goes into the check, the handle does go into a vise
with the turning device easily accessible, and the wire to be coiled
reasonably pulled straight.

I use a piece of chamois to hold the wire firmly in my right hand and
guide the wire to a close coil, turning the drill with my left hand. I
tend to use either hand easily so it is not a problem. Having the
ability to control the speed of the drill avoids and overlapping of
the wire.

To facilitate the ease of removing the coil, I have sprayed the
mandrel with Pam or similar.

For a bit more automated coiling, I use a cordless screwdriver, which
also turns at a far more manageable speed.

If you get the urge to do chains, the links can be made the same way
preferably using a wood dowel, after completing the coiling, tape
along the long side, and use a spring steel fine cutting blade in the
Dremel or Foredom, exercising extreme caution.

Enjoy and have fun,
Teresa


#16

The website shown (micromark) indicates no such item., Could you be
mistaken as to where you purchased the no-kink benders?? Thanks


#17

I also got my tube benders from Micromark. Maybe they stopped
carrying them, or perhaps they’re only in the regular catalog and not
the online one. Try calling them. It’s a handy item. Dee


#18

Small Parts Inc. sells tubing benders. You can get a set of six
ranging from 1/16" to 3/8" for about $7. Their website address is
www.smallparts.com and their e-mail address is parts@smallparts.com.
They have a terrific catalogue with many very usefull small parts and items.