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  1. #1
    Join Date
    Jan 2018
    Location
    Aldinga Beach.
    Age
    73
    Posts
    148

    Default Twin belt belt grinder.

    I thought I’d make a belt grinder for sharpening various things, this is what I came up with. I made the grinder to take 25mm x 762mm belts mainly because they are available in such a wide range of grits and also because they are small. The motor is from a 4” bench linisher that fell apart, four drums are of Delrin and two of steel . The drum arms are of 40mm x 10 mm topped with 40mm x 5 mm for the belt adjusters. The bearing housing was turned up from a piece of 40mm scrap, the remainder of the frame was made of 35mm x 2mm RHS.

    I had almost finished the project, but then I thought, why have one belt, two would be better, so I dismantled the framework made up another drum arm to match the first and made a new frame from 40 mm x 2mm RHS.

    Not quite finished yet as it's only tacked together and one on the arms must be a little off square. Might have to get another motor though I think, this motor struggles a bit trying to spin two belts.
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  2. #2
    Join Date
    Apr 2016
    Location
    Perth WA
    Posts
    6

    Default

    I love the simplicity and bigger is better.

    Thanks for sharing

    Cheers

  3. #3
    Join Date
    Apr 2009
    Location
    Ballina N.S.W.
    Posts
    644

    Default

    onanonanon,
    Interesting design, from the pictures I cannot see if you have a method of locking the belts spring mechanism. I feel the belts will come of in use if you just rely on spring tension.Belt sander do require quite a bit of power, I have a 3hp single phase motor on my 72" * 2" one.
    Bob

  4. #4
    Join Date
    Jan 2018
    Location
    Aldinga Beach.
    Age
    73
    Posts
    148

    Default

    I've had it going and the belts haven't come off. Just as a matter of interest though, I have both a Hafco L-69A linisher and a BS-48 belt grinder., neither have locks on the spring mechanism. A question: Why would the belts come off if just relying on spring tension? That spring tension is there for that very reason 'to stop the belts from coming off, and, I assume, to allow for differences in belt size. They all vary in size from manufacturer to manufacturer.

  5. #5
    Join Date
    Apr 2009
    Location
    Ballina N.S.W.
    Posts
    644

    Default

    OK if you have used it and they don't come off. My thought was that as you apply varying pressure as grind the flexing of the spring would allow the belt to walk sideways.
    Bob

  6. #6
    Join Date
    Oct 2007
    Location
    Alexandra Vic
    Age
    69
    Posts
    654

    Default

    With a few years metal polishing experience, (5-10HP 2850RPM polishing lathes driving belts via 300mm wheels, just a slightly crowned turn around wheel, some spring tension, and carefully adjusted tracking control), belts will stay on the wheels unless you do something like ripping part way across the belt. Then you will have a belt section trying to flay anything in range while the belt tries to walk over the the crown in the turn around due to uneven tension on each side.

    Basically once tracking is set for the particular system, belt retention is controlled by the turn around crown and the belt tension.
    I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.

  7. #7
    BobL is offline Member: Blue and white apron brigade
    Join Date
    Feb 2006
    Location
    Perth
    Posts
    7,182

    Default

    I don't have a spring tension lock on mine either and I've found that all you need for small belts is crown made of electricians tape. For 50 mm wide belts I found a layer of tape two tape widths wide and then a single layer in the middle over the top of the previous layer formed enough of a crown to help keep the belts on.

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