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Repowering my Crescent 20

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  • Repowering my Crescent 20

    my 1915(approx) cresc ent 20 bandsaw is running at 2000 fpm using a delta 1hp repulse induction motor.
    im considering replacing the motor with the 3hp ri motor that i picked up last fall and raising the blade speed by installing a larger motor pulley. the pulley on the saw is a massive old 12 inch that i have never been able to remove! so it stays!
    recommendations? is 3000 fpm too high for such an old machine with babbitt bearings?
    the saw is running well at 2000 but can be easily be stalled when resawing so feed rate has to be slow.
    the blade im using is an old 3 tpi but it was never used when i got it so "new old stock"
    my shop is a beaver lodge
    steve, sarnia, ont




    1940's Craftmaster Lathe

    https://www.facebook.com/artistryinwoodca/
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  • #2

    Re: Repowering my Crescent 20

    I'd say you want about 5000 FPM for resawing, some people may have a different preference here. That would translate to around 955 RPM (5000/(20pi/12)) at the 12" pulley, which I believe is more than safe for a babbitt. You would want a 6"-7" pulley for a 4-pole motor (1725 RPM) and a 3" pulley for a 2-pole motor (3450 RPM).
    washboard likes this.

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    • #3

      Re: Repowering my Crescent 20

      I would be inclined to use a 3 phase motor and vfd. As you know this will give you complete flexibility over blade speed. Cutting efficiency is always a combination of blade speed, rate of feed and teeth per inch.
      redlee likes this.

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      • #4

        Re: Repowering my Crescent 20

        You have babbit bearings, unless you want to do a pour in the future, you want to be careful what speed you run at. There were mainly two types of babbits used in old machines, lead based for slower machines and tin based for machines that required higher speeds such as jointers and planers. Bandsaws which required less than 1000 rpm were mainly lead based, the lower you stay below that speed the longer your bearings will last before requiring a new pour.

        3000 sfpm is a good speed for your machine and will keep you below safe bearing speeds for your babbit bearings for long life. Timberwolf recommends 3000 sfpm for their 3 tpi re-saw blades.

        Having the capacity to inadvertently run for a period of time at higher speeds could end up being alot more work soon after.
        Leo Van Der Loo likes this.

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        • #5

          Re: Repowering my Crescent 20

          i suspect the babbitt is original and the upper wheel has no babbitt, its just a steel spindle running in cast iron!
          both are in great shape, run smoothly and feel tight' yeah they get lots of oil
          my shop is a beaver lodge
          steve, sarnia, ont




          1940's Craftmaster Lathe

          https://www.facebook.com/artistryinwoodca/

          Comment


          • #6

            Re: Repowering my Crescent 20

            Not adding anything new , but agree that the 3000 fpm will make your saw run like a top. With that 12" on the saw , getting a 6" for the motor will be reasonable to get. Show when you get a chance!

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            • #7

              Re: Repowering my Crescent 20

              Originally posted by washboard View Post
              Not adding anything new , but agree that the 3000 fpm will make your saw run like a top. With that 12" on the saw , getting a 6" for the motor will be reasonable to get. Show when you get a chance!
              yeah 3000 fpm is what im considering, now to find a 6 inch pulley with a one inch bore
              my shop is a beaver lodge
              steve, sarnia, ont




              1940's Craftmaster Lathe

              https://www.facebook.com/artistryinwoodca/

              Comment


              • #8

                Re: Repowering my Crescent 20

                Originally posted by stevem View Post

                yeah 3000 fpm is what im considering, now to find a 6 inch pulley with a one inch bore
                What RPM is your motor?

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                • #9

                  Re: Repowering my Crescent 20

                  Originally posted by stevem View Post

                  yeah 3000 fpm is what im considering, now to find a 6 inch pulley with a one inch bore
                  This one is 6.75" but might be close enough to work https://www.princessauto.com/en/detail/6-75-in-spoked-cast-iron-sheave/A-p8046120e

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                  • #10

                    Re: Repowering my Crescent 20

                    Originally posted by Scott Walsh View Post

                    What RPM is your motor?
                    it's an old 4 pole repulse induction motor, 1725 rpm, yes it weighs a ton!!

                    right now the is all apart for cleaning, painting etc etc. its allready had new bearings.

                    that pulley from pa will be fine im sure, now i'll have spokes everywhere!!
                    my shop is a beaver lodge
                    steve, sarnia, ont




                    1940's Craftmaster Lathe

                    https://www.facebook.com/artistryinwoodca/

                    Comment


                    • #11

                      Re: Repowering my Crescent 20

                      Originally posted by stevem View Post

                      it's an old 4 pole repulse induction motor, 1725 rpm, yes it weighs a ton!!

                      right now the is all apart for cleaning, painting etc etc. its allready had new bearings.

                      that pulley from pa will be fine im sure, now i'll have spokes everywhere!!
                      You'd want a 4" Pulley to do 3000 SFM. That 6.75" pulley would do over 5000 SFM.

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                      • #12

                        Re: Repowering my Crescent 20

                        Originally posted by Scott Walsh View Post

                        You'd want a 4" Pulley to do 3000 SFM. That 6.75" pulley would do over 5000 SFM.
                        Yup, 4” pulley on the 1725RPM motor will give you just over 3000SFM on the blade.

                        Have fun and take care
                        Leo Van Der Loo

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