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  1. #1
    Join Date
    Oct 2020
    Location
    USA
    Posts
    1

    Default How to expand copper tube?

    3/4-inch copper tube is commonly used in USA for carrying water in buildings and homes. Cheap and plentiful.

    I have a non-plumbing application where I need to expand a few inches of one end of a length of tubing.

    Nominal 3/4 inch size tubing is 0.785-inch I.D. and I need to expand this just a hair to 0.787.

    The I.D. needs to be expanded evenly to accept a cylindrical 20mm slug (which measures 0.787). How to accomplish this? I don't want to drill this out as I want to maintain the full wall strength. The "slug" is precision and needs to be a slip-fit so can't just hammer it in.

    Any suggestions welcome.

    Thanks.

  2. #2
    Join Date
    Sep 2014
    Location
    Elimbah Qld
    Posts
    24

    Default

    https://www.youtube.com/watch?v=iFOTxT1qkLk
    you could make one like this

  3. #3
    Join Date
    Oct 2004
    Location
    Southern Highlands NSW
    Posts
    1,894

    Default

    It might work to make a tool of slightly bigger diameter to push into your pipe, of polished smooth steel, lubricated.
    The pipe end should be soft annealed.
    Maybe for the length of yours, a cylinder of slightly more than finished OD will help keep the shape.
    It could be split at one end to grip the tube.

  4. #4
    Join Date
    Nov 2019
    Location
    Brisbane
    Age
    69
    Posts
    452

    Default Expanding copper tube

    Hello from BC.
    Google roller tube expander. They are used to expand copper tubes in model steam boilers. There are a few articles on building them. I have bought some from India and they look to be of good quality. It will be hard to expand just enough and not lock the tube to your die.
    Regards
    BC

  5. #5
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Guys,

    I've made tube expanders similar to those in the video, and used them on both copper and aluminium tubes. They are easy to make and using mild steel for a one or two off usage, throw away when done.
    Best Regards:
    Baron J.

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