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  1. #1
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    Default Square to round adapters

    Anyone wishing to make custom "square to round" adapters for machinery may like to take a look at this Youtube video clip by Ron Covell.


    The first half shows how to make the adapter and the second half is how to weld the pieces. However, I just pop rivet and silicone mine.

    The key to making good adapters is making an accurate pattern and Ron shows how to do this using a rolling former method.

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  3. #2
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    I’ve always thought it would work to make them the same way you make your bell mouth hoods, using a wooden former for the shape. But haven’t needed one to actually try that.

  4. #3
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    Quote Originally Posted by Colin62 View Post
    I’ve always thought it would work to make them the same way you make your bell mouth hoods, using a wooden former for the shape. But haven’t needed one to actually try that.
    I've made a couple that way but it doesn't work when the narrower dimension of the rectangular end is smaller than the diameter of the round.

    Check this out.
    Its my attempt to make a PVC former for "40 x 250mm rectangular" to "150mm round"


    former.jpg

    Now imagine "tube' of PVC wrapped around it - there is no way to get it off the former.
    The sloped sides on each adjacent face are in opposite directions so the won't allow for the PVC to be removed.

    I was at the point of turning the RHS end of the former into a "150 mm round" when I realised it wouldn't work.

    So I went for the rollation method.
    The generic 2HP 10" planer/thicknesser dust control issues

  5. #4
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    A breeze for a 3d printer.

  6. #5
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    Quote Originally Posted by DavidG View Post
    A breeze for a 3d printer.
    The small adapter definietely - although I'm certain I could beat most of them in terms of time and cost.
    The bigger one - not many consumer level printers have a big enough foot print - yet.

  7. #6
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    Quote Originally Posted by BobL View Post
    I've made a couple that way but it doesn't work when the narrower dimension of the rectangular end is smaller than the diameter of the round.

    Check this out.
    Its my attempt to make a PVC former for "40 x 250mm rectangular" to "150mm round"


    former.jpg

    Now imagine "tube' of PVC wrapped around it - there is no way to get it off the former.
    The sloped sides on each adjacent face are in opposite directions so the won't allow for the PVC to be removed.

    I was at the point of turning the RHS end of the former into a "150 mm round" when I realised it wouldn't work.

    So I went for the rollation method.
    The generic 2HP 10" planer/thicknesser dust control issues
    Good point, thanks.

    I suppose you could cut the former into pieces, and by sliding one piece out, create sufficient room to remove the other pieces. But that’s starting to become a major hassle.

    I’m on my phone, so not really up to editing your pic to clarify it properly.

  8. #7
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    Slicing the former up would work
    BUT
    The joints would need to be very smooth because when the PVC cools it shrinks and would force the pieces together.
    Slcing would also have to allow for kerfs.
    Attached Images Attached Images

  9. #8
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    Looking at Bob's picture...
    One could cut the PVC to get it off the form then glue it back together.

    Or, for experimental prototyping, glass fiber over foam can be quick and cheap, provided one has skills and a small, appropriate workshop space. Trouble is that people are so interested in learning their new computer controlled tools, like 3D printing, that less people learn this other stuff.

  10. #9
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    How rough would fiberglass over foam be? Smoothness become really important on elongated slots which have a high perimeter to cross sectional area ratio.

  11. #10
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    It can be smooth. If the foam is faired, then packing tape skillfully applied, the surface can be smooth. That's the cheap, easy way to do it. Small defects can be sanded out. Finished to any level you want.
    We use the methods we know and that get us excited....

    My guess is that composites could be viable for short production runs of novel dust ports. That would probably be in parts be made over male molds with perfect surfaces.

    But I think the PVC male forming idea is maybe the most fun, do-able thing going at the moment....

    (edit: added info)

  12. #11
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    I remember using poly foam as lossy formers when I worked in high rise concrete form work 40 years ago. Quite complex service ducts, even some AC ducts were packed with foam and concrete poured over the foam. Then petrol was poured onto the foam to dissolve it. We had a few fires and even an explosion . Wouldn’t be allowed these days.

  13. #12
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    I used some 150mm PVC pipe, a wooden inner and outer former and a heat gun. The pipe was fitted to the inside of the outer former which became the base to connect to the extractor

    IMG_0983.jpgIMG_0521.jpgIMG_0980.jpg

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