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Thread: question about lathe pulley size

  1. #1
    Join Date
    Jan 2008
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    question about lathe pulley size

    I am slowly setting up my lathe, as soon as i can get the vfd it will be working. but i noticed that i will need to get some puleys. the lathe has 4 step pulleys, the motor that i got it with only had 1 pulley and that one is equal to the smallest pulley on the spindle. what size pulleys should be gotten for the motor end? i was thinking that i should get one that is the same as the smallest one and one that is the same size as the biggest one, then i would have the top and lowest speeds, and since rought heavy work wouldnt be done on the inbetween i could just set it to the top speed pulley and then use the vfd.

    any thoughts?
    14x48 custom 2hp 9gear lathe
    9 inch pre 1940 craftsman lathe
    36 inch 1914 Sydney bandsaw (BEAST)
    Wood in every shelf and nook and cranny,,, seriously too much wood!

  2. #2
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    Jan 2008
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    on second thought actual sizes would help better.
    here is the sizes of the step pulleys on the spindle, by eyeball with a ruler

    4 inches
    3 1/2 inches
    2 1/2 inches
    2 inches
    these are the outer diameters of the pulleys, the walls

    the inner diameter of the pulley is a hlf inch less, except for the smallest one which is 1 inch.

    what pulleys size should i get for the motor?

    we are going to mount the motor to a drawer slide and then mount that to a board that is on a hinge, so the motor can go up and down a little to change the belts. the hinge will have a spring on it
    14x48 custom 2hp 9gear lathe
    9 inch pre 1940 craftsman lathe
    36 inch 1914 Sydney bandsaw (BEAST)
    Wood in every shelf and nook and cranny,,, seriously too much wood!

  3. #3
    Join Date
    Jan 2008
    Location
    Abilene, TX
    Posts
    223
    Hello Curtis,

    Certainly I'm not the be-all, end-all advisor on this topic, but I can tell you what I have on our little lathe. The multiple diameter pulley is on the spindle, then the drive on the motor is just the smallest size available. Only. My guess would be a 2" pulley. So the motor drive/pulley doesn't have anything changeable - and it's worked just fine like that for well a decade.

    With the upper pulley I can change speeds from about 475 rpm up to about 1,775. Nice range to do what I do. On the big lathe I really like the VS so I can slow it down to a crawl or really hype it up there, but it all depends on what you're doing.

    Hope that makes sense. I just found I didn't need the lower pulley to be a multiple at all, the spindle multiple does everything I need and yep, it's a manual change of course, but really easy and very fast. My husband mounted the motor on a hinge mount so it's really easy to change the belt from one size to another. Very convenient. So frankly it's probably identical to your plans and it works very well. Anyway hope that helps you!

    Jude

  4. #4
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    Dec 2006
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    Loretto, Ontario (in the sticks, north of Toronto)
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    Curtis,

    Get a pulley that will match what you have and mount it in reverse of the original pulley so the largest diameter of one pulley will mate with the smallest diameter of the other pulley. This way you will always be able to use the same belt for all 4 grooves. Otherwise, you will have to do a bit of calculating to get the belt to match the pulley diameters and the pulley spacing, etc.
    Regards,

    Chris

  5. #5
    Join Date
    Jul 2007
    Location
    Childress, Texas, USA
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    1,930
    Curtis, my Little Vic VL100 is set up like Chris explained. And it uses a small belt that has 4 grooves on it. Each step of both pulleys have grooves also.
    A single pulley on the motor, centered on the Lathe's step pulley, will work if the pulleys use a simple V-belt.
    But if the Lathe's pulley is one of those that uses a "grooved belt" (I don't know what they're really called), you'll need to align the pulley with the proper grooved step each time to keep the belt from wearing prematurely. Therefore, the motor should be able to be moved slightly along it's axis to keep it aligned when changing speeds.
    I hope this makes sense??
    Allen
    The good Lord didn't create anything without a purpose, but mosquitoes come close.
    And.... I'm located just 1,075 miles SW of Steve Schlumpf.

  6. #6
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    Loretto, Ontario (in the sticks, north of Toronto)
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    A multi-V or PolyV as GoodYear trademarks it, doesn't like too much misalignment. For any style of belt, depending on the length of the span from pulley to pulley, they don't like to be out of alignment by more than 1mm or about 1/32".

    You'll know if you are too far out because there will be visual clues when you observe the belt line while it is running. It will show the misalignment when it runs. If it's really out there may even be some vibration or noise as the belt is tending to rub more on one side of the groove than the other.

    If you want to make a cheap, high-tech alignment tool, mount a cheapo laser pointer to a piece of wood in a way so that the laser will sit in the middle of a groove, any groove, on one pulley and then point it to the other one. It will show the relative position of the pulleys to one another. It's a quick and dirty method that we use at work when checking alignments of pulleys on car engine accessory drives.
    Regards,

    Chris

  7. #7
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    Jan 2008
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    Paradise PA
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    is there a good place to get the step pulleys? the local stores only have single pulleys and the motor shaft isnt big enough to mount 4 seperate ones
    14x48 custom 2hp 9gear lathe
    9 inch pre 1940 craftsman lathe
    36 inch 1914 Sydney bandsaw (BEAST)
    Wood in every shelf and nook and cranny,,, seriously too much wood!

  8. #8
    Join Date
    Oct 2006
    Location
    East Brunswick, NJ
    Posts
    1,475
    Grainger, McMaster-Carr, and Surplus Center are all good places to get pulleys, and other drivetrain parts.

    McMaster-Carr has 4 speed step pulleys for about $15.

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