Pipe Bending ?

[Exie]

Hi Folks,

Well, I've started to get all the gear needed for my customer cooler. I've got some flat copper bar, and some flat allu bar too for prototyping, I've also got some copper tube and some allu tube as well.

My current issue is, how do I bend it ?

I'm trying to make a "U" shape, and as I understand, the common methods are to use a pipe-bending spring, or a pipe bending tool. I havent been able to find an 8mm spring to fit inside my tube, and havent found a bending tool that will make a sharp enough angle.

Any ideas ?

[frenchnew]

The spring is fitted over the tube and not in it FYI.


Depending on how tight you want that bend, it might not be feasible without kinks or fractures of the tube. You will have to try it.

Best regards

frenchnew

[Exie]

Thanks,

The outer diameter of my tube is 10mm, any idea where I could get a 10mm spring from ? (in Australia).

I've checked a few stores like Bunnings, Thrifty Link, Just Tools etc, but havent had any luck so far.

[frenchnew]

Sorry I wish I could help but since I am from Montreal, Canada I have no idea where you would find these.

Since the size you mention is slightly bigger then 3/8 inch, I would suggest you look into local Auto Parts stores in your area and ask for springs to bend brake tubing. It also might be a good idea to bring a sample of the tubing with you to try it out.

The spring to bend 3/8 inch tubing might be too small and you might have a hard time to get the tubing in it but this would prevent the tube from kinks

Best of luck to you

frenchnew
Montreal, Canada

[Bleeptech]

For a quick and dirty (literally) way to bend copper/aluminum/brass tubing is to pack
it full of sand and cap the ends.. (Old moonshiners trick)

You can do some pretty tight bends this way and if it starts to kink you can gently
massage it with a mallet to keep it rounded out.

Use a lead/brass/plastic mallet to avoid splitting the tubing..

Bleeptech

P.S. There are 2 options for production/exhibition..Mandrel bending and tubing rollers...
Ask me if you need more info.

[bigben2k]

Good tips: I was going to say the same!

Plumbers and AC (air conditioning) technicians also use a tube bender: looks like a fancy pair of pliers. Maybe you know someone that has one already?

[ibmkg]

Bleeptech:

Nice. Do provide additional info.


Does any one know how to 'straighten' the tubing? Usually Al and Cu tubing come in rolls. I for some reason need to straighten up, upto a meter. Using mere hands results in little curves all the way giving ugly looks to the tubing.

[Bleeptech]

BENDING:

OK.. For easy to obtain/use tubing benders try your local auto parts chainstore. Go to Autozone, Checker/Schucks/Kragen, Napa, etc and tell
them you're looking for a brake-line bender.. It'll be in the tools section
with the brake repair tools (<$20 for a decent one that does 1/8" - 3/8")
or you may be able to borrow a loaner after paying a deposit.

These are a "shoe" type bender and are OK for 0-90 bends in Al/Cu/steel.. Here's Harbor Freights $7 version so you have an idea what to look for.

http://www.harborfreight.com/cpi/cta...temnumber=3755

For more complicated bends you want a spring type bender or a tubing roller.

The spring type benders usually look like a screen door spring with a belled end.

If you cant find one look for a screen door spring, casement window spring
or other spring the right I.D. to slip over your tubing


Here's how to build a tubing roller with a drill press and a few other tools.

Build a tubing roller link
http://www.motherearthnews.com/Green..._Tubing_Roller


UNBENDING

1:The Mandrel.

Best thing I can tell you to do is find a piece of the hardest steel bar you can, a hair
smaller in O.D. than your tubing I.D. and longer than the section of tubing you want to work.
Taper one end to 50% of the O.D. for a length of ~3 x O.D. and finish it with a rounded point.

If you're not using seamless tubing you may have to grind a notch for the seam to lay in
along the length of the bar or use a smaller diameter bar.

2: The Smoothers

Refer to

http://www.motherearthnews.com/Green..._Tubing_Roller

for instructions on how to make the 2 rollers you will want to smooth the
tubing against the mandrel.
You need to make the cranked roller and one of the follower rollers.

3: The Frame

Refer to the diagram for the tubing roller and make a frame that will hold
your 2 rollers against opposite sides of your tubing.
Remember the adjustment slots for the cranked roller to set your roller to roller distance.

4: How it works

Straighten your tubing as much as possible and insert the end of the mandrel into it.

Keep straightening and pushing until you have enough of the mandrel into the tube
to allow for the length of tube you want too work.

Run it back and forth through the rollers several passes rotating it 30-90 degrees/pass.

With any luck you'll now have a piece of tubing that now has a uniform exterior finish.


Did I miss anything?

Bleeptech

[jaydee]

Yeah sand is ok. Try to get the sand as fine as possible. Sand with clay in it seems to pack a little better. You can use a kitchen sifter to sift the sand or screen.

Also if you anneal (heat dull red hot and let cool) the copper first it makes it easier to bend.

Another method is to fill the copper pipe with molten solder and then let is cool hard then bend. Then heat back up and the solder will flow out. Not recommended for water cooler though as solder will remain on the walls of the pipe.

[billbartuska]

For plastic pipe:
http://www.ocforums.com/showthread.php?t=469114

[Lil Big Mec]

Originally Posted by jaydee

Yeah sand is ok. Try to get the sand as fine as possible. Sand with clay in it seems to pack a little better. You can use a kitchen sifter to sift the sand or screen.

Also if you anneal (heat dull red hot and let cool) the copper first it makes it easier to bend.

Another method is to fill the copper pipe with molten solder and then let is cool hard then bend. Then heat back up and the solder will flow out. Not recommended for water cooler though as solder will remain on the walls of the pipe.

If you heat the pipe with the sand inside, do make absolutley sure the sand is dry before you cap the pipe, or it can "explode" like a mini pipe bomb due to water vapour building pressure inside the pipe and splitting it open. I witnessed this on a friends race car, when they were bending up a rollcage for it. The welder who was doing the heating had some shrapnel in his chest and nasty sandblasting done to his face. Fortunately, he was wearing safety glasses, so he wasn't blinded. Has a pretty scarred/weathered face now though. Granted the tubing was 1 1/2" so it held a lot more sand but I still wouldn't want a small copper pipe bursting in my face and scaldin g me with steam

[jaydee]

Originally Posted by Lil Big Mec

If you heat the pipe with the sand inside, do make absolutley sure the sand is dry before you cap the pipe, or it can "explode" like a mini pipe bomb due to water vapour building pressure inside the pipe and splitting it open. I witnessed this on a friends race car, when they were bending up a rollcage for it. The welder who was doing the heating had some shrapnel in his chest and nasty sandblasting done to his face. Fortunately, he was wearing safety glasses, so he wasn't blinded. Has a pretty scarred/weathered face now though. Granted the tubing was 1 1/2" so it held a lot more sand but I still wouldn't want a small copper pipe bursting in my face and scaldin g me with steam

Yeah, I can see that happening. Good point. What you describe sounds like he was trying to heat the metal up in order to bend it easier while the metal was still hot.

Annealing is the process of heating the metal up and then cooling it down to make the metal softer and easier to work with. So it should be cold before you even start working with it.

[jman1310]

10mm copper pipe can be straighten by hand

stretching the tube while twisting will work

take care not to twist to much - not more a turn or 2 a foot (3-6m)