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How do you bend silver tubing?


#1

Hi Everyone!

This is my second time posting on Ganoksin and I’m so pleased; what
a fantastic resource, powered by such a diverse community. So, I
frequently design my pieces with bails made of curved tubing
(anywhere from 1/2 inch long to 2 1/2 inches long), but thus far
have not found a very good way of bending the tubing into an arch
without denting or collapsing it. I have been told that you can use
springs, but I have yet to find springs made for this (the hardware
store’s springs are too big). I have also tried pulling the tubing
through a drawplate at an incline, and ended up with a curve but very
marred and dented tubing. Any ideas or suggested directions would be
immensely helpful.

Thank you! Nisa


#2

There are tubing benders avialable for common copper pipe sizes,
1/4", 3/8", etc. perhaps even 5/16", & 3/16" Outside Diameter.
Imperial is a good brand of tubing tools. If you work with Air
Condition parts suppliers they use the O.D. of tubing, plumbers use
a “nominal” except sometimes in the small sizes. (1/2" nominal is
5/8" refrigeration size) There are also different wall thicknesses
etc.

I would use dead soft tubing and a standard O.D. size if possible.
Imperial makes a nice little bender which functions kind of like a
pair of pliers. This may work well for your purpose.

Dan Wellman


#3

Hi Nisa,

Just a couple of weeks ago, I found some very small springs that
look just like the bigger tubing bender springs that I’ve seen at a
local hobby store (one that caters to the radio control airplane and
car constructor crowd).

The kit is made by K&S Engineering, it costs $3.19, and has 5
springs that are flared on one end and sized for bending tubes from
1/16" to 3/16" o.d.

They work quite well! The springs support the outside of the tubing
and keep it from kinking or flattening, and do not mar the tubing at
all.

I googled and found them on ebay and on an online hobby site if you
can’t find them locally - I entered “k s engineering tubing bender
321” (the kit part number is #321) into google and the first two hits
had places to buy it from…

good luck!

Kevin
Blue Dog Forge
http://www.bluedogforge.com


#4

Look here at the bottom of the page.
http://www.metalliferous.com/pdf/tools/TV1BenchTools.pdf

Bill

Bill, Deborah & Michele
Reactive Metals Studio, Inc
928-634-3434, 800-876-3434, 928-634-6734fx


#5

Nisa,

There are springs that are made specifically for this. They can be
found at:

http://tinyurl.com/yuc6m3

They are $4.95 for a set of 5 that range in size from 1/16" to 3/16"
OD. You insert the tube in the spring and bend it around a mandril or
other object of the diameter that you want and slide the spring off
the tubing. The above link is from Micromark. There are also other
companies selling the same thing.

Joel Schwalb
www.schwalbstudio.com


#6

Nisa, there’s two ways in general to bend tubing. One is to use
springs on the outside - that’s what tubing benders use. There’s
every spring imaginable in the world, the problem is finding the
right one. This is to get a “perfect” bend. there’s things like
conduit benders, but they don’t give a “perfect” bend. The other way
is to fill the tubing with something, bend it, and remove the
filling. Traditionally people use lead, melt out the lead and then
soak in HCl to strip it, or fill it with water, freeze it, and then
unfreeze it. BTW, you’re not gonna get 1/2" tubing bent easily - bend
1 1/2" and then cut to length. Maybe others will have other ways, but
those are the usual…

http://www.donivanandmaggiora.com


#7

A number of techniques present themselves, suitable steel, brass or
copper wire can be inserted and subsequently etched out with an
appropriate acid. Filling the tube with a low temperature metal such
as bismuth although this is somewhat problematic in small internal
diameter tubing, and subsequently melt out the filler. The easiest
technique I have found on narrow diameter tubing, 0.5mm - 3.0mm
internal diameter is to cap or crimp one end, fill the tube with a
suitable fine sand, ( I use 300 grit tungsten carbide sand blasting
media), after filling the tube ensuring that you gently tap during
the filling process to settle the media, simply crimp or solder a
cap on the other end and bend. If you are using seamed tubing it is
best to ensure that the tubing seam is on the internal radius of the
curve. Cut off the crimped/solder capped ends to length and tap/blow
out the media. If it is necessary to anneal during/after bending and
before extracting the sand it is safer to allow the tubing to air
cool in case any pickle has entered the tube.


#8

Here are my 2 methods, documented in many textbooks:

  1. fill the tube with wax, bend away, then melt the wax out

  2. run the next smallest tube inside the one you want to bend (with
    oil lubrication), then bend, then pull the inside smaller tube out -
    example: a 3/16" (6/16") OD tube will fit snuggly inside a 7/32" tube
    (or a 5/32" inside a 3/16", etc.) - and bend away - this works for
    slight bends - higher degrees of bending ==> the harder it is to
    remove the inside tube (even with lots of lube).

And the following “spring methods”, which I have never tried.

  1. Micro-mark (mircomark.com) carries a set of 5 smaller springs for
    bending tubes (these fit over the outside of the tube to be bent.
    ID’s of 1/16 inch, 3/32 inch, 1/8 inch, 5/32 inch and 3/16 inch. May
    not work well with silver tubing manufactured metrically. See here:

http://tinyurl.com/yvtqlu

  1. some jewelry supply houses have kits of metric-sized jewelry
    springs that will fit a variety of silver/gold tube sizes.

Good luck!
Jon


#9

I make tube bails for LOTS of pieces. I have tried everything, even
the springs. After trial and tribulation, I pioneered my own method.

Here’s how it goes

  1. First cut your tube from the straight stock. The tube length
    should be about 10-12mm longer than you want the actual bail to be.
    You will be cutting this extra off at the end.

  2. Anneal

  3. Find something that fits snuggly into the tube, I use the handles
    of needle files.

  4. I use a large oval shaped bracelet mandrel to bend the
    tubing…you can use whatever you want, but I would go for a
    more gentle curve otherwise you risk making an uneven bend. I
    support the mandrel on my bench pan and put the end in my lap. You
    want to have the larger end farthest from you. Insert the file
    handles into the ends of the tube, just enough to get a good hold on
    it. Put your thumbs on top of the tube and push down to bend the
    tube over the mandrel.

  5. Now you have a nicely curved tube bail. There are probably some
    bumps from the file handles, just cut them off and you have a nice
    bail ready to attach.

Good Luck!

Brooke
www.bellebrookedesigns.net


#10

Hi Nisa, This is how I bend tubing without denting it. First I plug
one end of the tubing. Then I drop a string or thread into the tube
depending on the size of the tube. Then I melt sodium thiosulfate
(photo fix) crystals and pour it into the tube. Then pull the string
out. This will remove trapped bubbles. After it re-solidifies, you
can bend your tube with fingers or pliers. I place one end of the
tube in a draw plate or bench block with a variety of holes drilled
in it. Make sure you have a close fit. The tube will bind in the hole
and allow for little tube waste. The chemical will make a cracking
sound as you bend the tube but will support the tube from the inside.
After you are done melt the sodium thiosulfate out of the tube by
placing it in hot water and your done. I think I found this process
in Oppi Untracht’s Jewelery Concepts and Technology, but I can’t say
for sure. Have fun.

Best regards, Kevin


#11

I used to fill the tube with molten candle wax by attaching a
syringe to one end and immersing the other in melted wax in a tin.
This does not stop the tube deforming completely - but it helps. The
wax melts out easily afterwards (back into the tin for next time) Oh
and be sure to anneal the tube beforehand. Others may have a more
cunning solution…

Andrew Macfarlane


#12

For small sizes you can use nylon fishing line, they do sizes up to
about 1.5mm if you ask. It then pulls out or burns out if necessary.

regards Tim.


#13

2 questions come to mind when reading this thread.

Can one make their own springs out of brass to fit the exact size of
tubing? If so what gauge would be good?

Can you shove a wire into the tube and bend it that way?

Thanks.
Carla
www.carlamfox.com


#14

Hello G.P.,

I discovered that a tight insert of 7-strand stainless cable works
great for supporting tubing. Annealed tubing can be bent to a tight
circle using this method. Bending against a wooden mandrel will
result in a good round circle. To remove the cable, lock it in a vise
and hand pull the tubing off. If the fit is especially tight, place a
parallel -jawed pliers in front of the tubing and pull. I keep 1.5
foot lengths of several diameters of cable for this application.

Sarah Nelson


#15
For small sizes you can use nylon fishing line, they do sizes up
to about 1.5mm if you ask. 

Good idea! And for larger tubing, trimmer line should work!

As a complete aside-- not appropriate for my own work, but you can
make rivets out of trimmer (weed whacker) line with a hot knife.
Might be fun for kids!

Noel


#16

I thought you would be interested in seeing the following item from
the Micro-Mark web site:

Description: 5-Piece Spring Type Tube Bender Set
http://tinyurl.com/3b3o7q


#17

It seems i remember something about a technique of using a rod of
aluminum inside of tube and after bending, then etching it out with
Muratic acid (HCl), also wax and then melt out, but with wax you
need to experiment which wax will work best…possibly sprue
wax…


#18

To bend tubing, use a spring type tubing bender. Can’t find the right
size? Make it yourself. Get a roll of annealed steel binding wire
from the hardware store and wrap it around the tubing the same as you
would for makng jump rings. You don’t need expencive spring types, or
messy acids. I’ve made many and I find they work quite well. If you
mess it up taking it off, make another one…it’s cheap enough, and
you’ll have plenty of wire left for the next one.


#19

I don’t know if this has been said or not, but.I use fine sand or
salt to fill the tube and tape up the ends and bend the tubing. low
tech but works great.'course it depends on the size of the tubing.

Susan


#20
but thus far have not found a very good way of bending the tubing
into an arch without denting or collapsing it. 

I think it will depend on the size of the tubing but one thing you
could try is the technique now used for bending the brass tubing
used in making wind instruments (musical) which is to fill the
tubing with ice… plug one end of the tube and fill it with water:
then place it is the freezer for a while until the water is all
frozen and bend it before it thaws out. The ice holds the tubing in
shape but melts away cleanly afterwards. Otherwise, you can fill the
tubing with anything which is fairly stiff such as hard wax, sand
etc.

Best wishes,
Ian
Ian W. Wright
Sheffield UK