Page 1 of 6 123 ... LastLast
Results 1 to 10 of 57

Thread: Tell me about.......V-belt lathe speeds

  1. #1
    Join Date
    Dec 2018
    Posts
    505

    Default Tell me about.......V-belt lathe speeds

    I got my Dad's Logan 9x17 vbelt drive lathe. As a kid I remember him saying 'this thing is too fast'.
    In my mid life I never used it very much. Now, I am semi retired and get time on it often.
    I find myself wanting to run it in back gears more often than not. playing with steel.
    It seems I almost never run it merely on the step pulleys, I now agree with dad, it is too fast.
    The motor is a 2 1/2" pulley, driving a 6 1/2".
    that 6 1/2" is the countershaft with the step pulley, that drives spindle.
    the slowest 'step' is about 2:1 ratio.
    I'm always on the lowest step, that unless I go to back gears, only then do I seem to want to get up on pulley steps.
    Are all the Logan or similar machines like this?
    Am I missing something? doing something wrong?

    The other day I tried a piece of 2" 4140 and it was a total nightmare. I briefly looked at speed feed table and my math told me I was on the slow step and neighborhood of 130 surface fpm
    I'm thinking the initial set of motor pulley needs to be in the neighborhood of 2" & 13", to drive the countershaft stepped pulley?
    What am I missing?

  2. #2
    Join Date
    Jan 2011
    Location
    Cinti,Oh
    Posts
    493

    Default

    Hmmm, don't sound right...typical would be 2" driving 10" or so....got a pic to be sure we are on the same page?

  3. #3
    Join Date
    Jan 2004
    Location
    Missouri
    Posts
    31,565

    Default

    You should have a double flat pulley, that the underside of the V-belt runs on. About 10" or so, yes, for the larger.

    This is mine, actually a Southbend countershaft, but very close to Logan, and it works with my model 200. The Wards have a countershaft similar to this, dunno about the Logan 9" machines.

    if it has a Logan "drivebox" the same type pulley will be in the drivebox.

    1601

    Keep eye on ball.
    Hashim Khan

  4. #4
    Join Date
    Dec 2018
    Posts
    505

    Default

    what 'drivebox' you speak of?
    Mine is very similar to your picture, except I got vbelts all the way, the motor mount and tension lever is the same type style setup.

  5. #5
    Join Date
    Jan 2004
    Location
    Missouri
    Posts
    31,565

    Default

    Quote Originally Posted by Ringo View Post
    what 'drivebox' you speak of?
    Mine is very similar to your picture, except I got vbelts all the way, the motor mount and tension lever is the same type style setup.
    Then it should hae a 2 diameter pulley like the one seen in the pic behind the flat belt pulleys. There should be a 2 groove motor pulley to go with that.

    The rpm at slowest non-back gear speed ought to be around 240 rpm at the spindle. net reduction from motor of around 7:1 without back gears
    1601

    Keep eye on ball.
    Hashim Khan

  6. #6
    Join Date
    Dec 2018
    Posts
    505

    Default

    Quote Originally Posted by J Tiers View Post
    Then it should hae a 2 diameter pulley like the one seen in the pic behind the flat belt pulleys. There should be a 2 groove motor pulley to go with that.

    The rpm at slowest non-back gear speed ought to be around 240 rpm at the spindle. net reduction from motor of around 7:1 without back gears
    it has 2 groove pulley on motor, and countershaft.
    the slowest speed is pulley about 2 1/2" driving 6 1/2"

  7. #7
    Join Date
    Jan 2004
    Location
    Missouri
    Posts
    31,565

    Default

    OK.

    The lathe in the pic has a 2.5" driving a 10" on the countershaft, v-belt. The 10" is on the ID of the belt, and is really equivalent to about 11" OD when you figure the belt thickness, and that is the number I'd use.

    The countershaft has a 3 step pulley, as does the spindle, oriented so large CS pulley step drives small spindle step, both flat belt pulleys. The small countershaft pulley step is about 3" diameter, and the large spindle pulley step is about 4 7/8" diameter. I measured these with a large firm joint caliper, and a ruler, so they are not perfectly accurate, but they are close.

    So, the ratios are 11/2.5 and 4 7/8/3, or a net of 7.15:1. Call it 7:1.
    1601

    Keep eye on ball.
    Hashim Khan

  8. #8
    Join Date
    Apr 2006
    Location
    citrus heights, ca
    Posts
    2,277

    Default

    Quote Originally Posted by Ringo View Post
    it has 2 groove pulley on motor, and countershaft.
    the slowest speed is pulley about 2 1/2" driving 6 1/2"
    It sounds like someone did a motor swap, what rpm is on the motor plate?

    Steve

  9. #9
    Join Date
    May 2015
    Location
    Somerset UK
    Posts
    2,445

    Default

    To be sure exactly what speed the spindle is running at, get one of these cheap laser tacho's, by doing a search on ebay: https://www.ebay.co.uk/itm/Digital-L...cAAOSw4JlcwXiC

  10. #10
    Join Date
    Oct 2014
    Posts
    469

    Default

    You could reduce the size of the drive pulley on the motor and that would help some but what you need is a lager driven pulley on the countershaft. As othershave said somewhere around 10 inches and probably a smaller pulley on the motor too.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •