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lathe drivetrain

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  • lathe drivetrain

    Good evening all,

    I'm about to return a restored Blaisdell lathe to service and am thinking up a drivetrain. This is a 13" x 30" from about 1870. I have the original countershaft, flat-belt pulley and brackets, as well as a couple of electric motors of 1-2 HP. Old literature makes me think I need about 160-180 rpm at the countershaft (steel spindle, plain bronze bearings).

    One possibility is a gearbox at 10:1 or 11:1. Such a setup means the motor would connect to one end, countershaft at the other, and I'd have to make up keyed couplings to suit (easy). The whole business would have to get set up on a welded frame, which doesn't exist yet.

    The other possibility is belt drive with two reductions of 5:1 each. I'd probably use a B belt, single sheaves. My only concern about this is the possibility of slip in the second stage. Thinking it would take some big wheels for this to work and am wondering if anybody else has already been down this road.

    Understand when I say "service", this is an antique enjoying an easy retirement. Perhaps the proper word is "play". Your thoughts are welcome.


  • #2
    Two 5/1 reductions would give you 25/1. One way to get your reduction would be to use a 5/1 followed by a 2/1. The smaller ratio in the second stage would not require a real small pulley and would help prevent slippage. You cold even use two belts for that stage. I think there is a lot of belt drive design information available from manufacturers like Gates as well as references like Machinery Handbook.

    I think a two stage belt drive would be preferable to a gear drive from both a cost and performance viewpoint. Your ratios do not have to be 5 and 2, you may get some pretty odd ratios with available pulleys. Any combination that multiplies together to equal the desired ratio, such as 4/1 and 2.5/1, will work. Remember that the effective diameter of a pulley is about half-way down the slot; this can be important for small pulleys especially.
    Don Young


    • #3
      Thanks, Don. Obviously I have more figuring to do. Will start with those references.



      • #4
        The "traditional method" of connecting a motor to an antique lathe is an old car transmission. Put a pulley on each end and you have 3 easily-selectable speeds to choose from. I've seen this on several old machines, including one of the lathes at the Buckley Old Engine Club.


        • #5
          Can you keep the Flat belt ?
          Do you want to keep the Flat belt?
          If you don't mind, it may be the best bet.
          Its quiet, smooth and authentic looking.
          I would use it on the largest pulley and run it off a jack shaft that has
          a V belt reduction from a 3 phase motor. then put a VFD on the motor
          and you will have all the speeds you want and it will be quiet too.
          The large pulley gives you non slip operation and the VFD handles the rest.


          • #6

            Will retain the flat belt, yes. The link between the motor and countershaft is what I'm puzzling through.

            Going over inventory to figure out what I can build with existing stuff. Any of three routes i.e. VFD, two-stage belt or gearbox would be fairly easy. Thanks.



            • #7
              The traditional 1880 lathe drive is a linehaft running the leengt of the shop powered by cCorliss engine fired by a schoolboy orphaned in some dimal fatal accident to a late employee.

              Practically, too bad you can't find an operable induction/repulsion motor made close to the era. 1120 RPM to 175 is what 8 to 1? What's the input pulley dia? 10" or so? They had V-belt back in the '20's and V-flat drives became common as single machines run by individual motors began entry into mall shops.

              Take your example from the machine shop in the Wright Museum at - is it Ford Museum? - or the Vermont Mueum of Precision.


              • #8
                If only I could pull off something like that i.e. a steam engine powering lineshafts, I'd be set. If only. Can't fire the boiler and make chips at the same time.

                Repulsion motors or lower speed motors i.e. under 1750 are tough to come by in these parts. The input pulley is 9", but I'm sure I can make do.