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  1. #1
    I need to make some bass ports for a small speaker - 400 of them!

    I was going to use PVC pipe which is easy to form when heated in an oil bath. However It takes a lot of time.

    Each speaker has 2x 20mm OD ports and if I could get 28mm OD pipe (1mm wall thickness) I would only need one per speaker. PVC pipe seems to go up from 25mm to 32mm, so no help. However copper pipe is 28mm with 1mm wall.

    Do you think I would be able to form it in the shape shown? How? I've seen a metal ram used for more basic expansion. I am thinking the end flare might be too extreme and crack the pipe. The edge of the lip needs to end up at 90 degrees to the pipe length. Any tips?

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  2. #2
    mekanik's Avatar
    Lives in Barrow in Furness, United Kingdom. Last Activity: 16 Hours Ago Has been a member for 9-10 years. Has a total post count of 786. Received thanks 96 times, giving thanks to others 176 times.
    Hi Tenson
    You could have a go @ spinning them you would need a to have a lathe big enough to take the pipe in the chuck, preferably gripped in soft jaws with a mandrel down the pipe, pipe would need annealing first. possibly a polished former/ template so they all come out the same. have a look on youtube for metal forming in the lathe. the special machines are pretty heavy duty but copper is soft when annealed.
    Regards
    Mike

  3. #3
    Annealed copper pipe may be pliable enough to get you such a severe change in section but I think it is unlikely to be easy to do.

    The best way would be to make a mandrel that you can spin a sheet of copper over, taking care not to kill yourself in the process. Look up sheet metal spinning it is how they used to make lampshades.

    Failing that, make from billet.
    https://emvioeng.com
    Machine tools and 3D printing supplies. Expanding constantly.

  4. #4
    I think you would be able to press form annealed copper sheet, with custom tooling, in several stages, with annealing between stages,
    Regards,
    Nick

  5. #5
    mekanik's Avatar
    Lives in Barrow in Furness, United Kingdom. Last Activity: 16 Hours Ago Has been a member for 9-10 years. Has a total post count of 786. Received thanks 96 times, giving thanks to others 176 times.
    Thing is guys he needs to make 400 !
    Do you have a lathe with a 32mm or greater mandrel bore ?
    Do you have a hydraulic press ?
    Whats the overall length of trumpets ?
    Last edited by mekanik; 21-08-2015 at 10:47 AM.

  6. #6
    I don't see how copper would be easier than plastic. Copper should be done in steps with annealing in between, that shape i mean.

    Plastic could be heated/ gas torch/ , pressed over shape and rapidly cooled in cold water. Then next...
    Last edited by Boyan Silyavski; 21-08-2015 at 02:07 PM.
    project 1 , 2, Dust Shoe ...

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