How to Bend Copper Pipe and Tubing Without Crushing It





Introduction: How to Bend Copper Pipe and Tubing Without Crushing It

I recently made a copper tubing coil to use in a solar-powered water-boiler and learned the right way and the wrong way to bend copper tubing.  The tubing is easy to bend when making large-radius curves, but is likely to kink or crush when trying to make smaller-radius bends.  I learned that I could avoid those problems by filling the tube with salt before bending.

Here's what I used.
  • .25 inch Copper pipe.  5 feet long
  • 1/4 cup of Salt.  (Fine, dry Sand would also work)
  • Tape
  • Funnel (or makeshift funnel)
  • Vice
  • Hammer
  • Hard Cylindrical Objects of various diameters.  I used a 3" diameter steel pipe and a 1.5" diameter socket-wrench socket.

Step 1: Fill It With Salt

  1. Your tubing probably came as a coil, so straighten it out to begin.  Use a flat surface like a table and roll the coil while holding one end on the table.
  2. Stand the tube upright and use some tape to cover the bottom hole.
  3. Use a funnel or other tool to pour the salt into the tube.  Fill it all the way to the top.
  4. Help the salt settle by tapping the tube on the ground.
  5. Refill with salt until it can't settle any more.
  6. Cover the top hole with tape.
Now you're ready to bend.

Step 2: Bend Using a Cylindrical Object

  1. Begin by bending your tubing into a much bigger circle than you want to end up with.  
  2. Clamp your cylindrical object in the vice and, by hand, gently wrap the big coils down to coil around the cilinder.  Sometimes a twisting motion can be useful, turning one end of your coil clockwise and the other counter-clockwise.
  3. Tap the tubing with a hammer (while it's on your cylinder) to help it reach an oval-shaped cross-section.  This lets it stay happy even when making tight coils.
  4. Continue the process with smaller and smaller cylinders until you are at the size you desire.
Take the tape off the ends and shake out all the salt!
You're done!

For more advice on bending tubing, check out this article.

If you're curious about the Solar Parabolic Water Heater, check out the instructable.



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    Even better, for even tighter results, fill the tbe with low-melting-point alloy. We use a material that melts at 80 C, and then steam it out hot after forming

    Brass trumpets are bent by filling the tube with soapy water, then freezing them. After forming, the water melts at room temperature.

    I've heard about the ice method. Why do they use the soap?

    I assume the soap makes bubbles that allow for the flexibility that pure ice would not allow.

    Only saw it on an episode of "How it's Made", but I would think that is for lubrication purposes.

    Trouble with ice is its crystalline, and cracks, leaving voids that tend to collapse the pipe. It might work in brass, in the very large relative curves in trumpets, but we make very fine coils

    Just keep in mind that most of these low temp alloys contain a fair amount of lead and cadmium, possibly with other toxic metals, so if this is for use to heat drinking water, those alloys should be avoided. Then again, with a heat exchange system, it may not matter,

    Not this one. Its largely bismuth.

    Once again i find you helping with your most-excellent advice Steve !

    GREAT Tip with the Low-Melt Alloy !

    Im very Curious though, whats the name of the low melt alloy you use and is it easily acquirable ?!?

    many many thanks too !!


    We use an alloy from a company called MCP in the UK. Its an alternative to "Woods metal" which contains antimony.