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motor for south bend 9A

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  • motor for south bend 9A

    my SB9A motor is a very old craftsman unit with 1/2" shafts out both ends. the shafts are quite tore up and motor is starting to vibrate some. my question is that atwoods farm supply sells a 5/8" shaft 1/2 HP fulley inclosed motor that can be wired to turn clockwise or counter clock wise. will this work for my lathe or should i look for something else?

  • #2
    IT should be fine. make sure it is 1725 RPM. My south bend has a 1/2 HP Leeson motor . Factory unit.
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    • #3
      You can get up to a 1-1/2hp motor on the same 56 frame base.If it were me I would bump up the hp to 3/4hp.If you can get an open drip proof motor for the same or less money I would also do that,since the TEFC motor will have a fan shroud and conduit box that may get in the way of things.Might be a good idea to set the old motor next to the new prospect to see if everything will fit before buying.
      I just need one more tool,just one!

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      • #4
        i'll get some more info, i think it was in the 1700 rpm range. and is a capasitor start motor.

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        • #5
          If your lathe has flat belts I don't think additional hp would help you any - the 1/2 hp motor you suggested should be okay.
          One other option you might consider...
          Since you are going to get a new motor you might look into a 3-phase motor and VFD combination.

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          • #6
            The 1/2hp on my 9a has enough steam to completely mangle up projects if something goes west. Mine uses a flat belt but I up-converted to a high-tech man made material that apparently has zip stretch in it.
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            • #7
              please excuse the nievness, but what are the advantages of 3 phase.

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              • #8
                I ask why not pop the ends and press in new bearings or bushings? Cheap and the motor is probably better quality than alot of new ones. As for the chewed up shafts dress down the burrs, they dont have any effect on the function unless you are constantly taking the pulleys on and off.

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                • #9
                  Depending on the old motor it may have a feature that the new motor doesn't. The original SB motors are 117vac "instant reversing" type. This means that they can be "plug" reversed even when operating at full rpm. This is usually only available with three phase motors but is a feature of the SB motor. In detail, it means that you can throw the switch to reverse at any time and the motor will reverse almost instantly, within less than one second.

                  If you are going to replace the motor with another 117 vac single phase motor you should ask about a "plug reversing" instant reverse motor. Here is an example:

                  http://www.slaymakersupply.com/pdf/l...itePurpose.pdf
                  Free software for calculating bolt circles and similar: Click Here

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                  • #10
                    Originally posted by quadrod
                    please excuse the nievness, but what are the advantages of 3 phase.

                    If you hook the 3 phase motor up to a VFD - (you can get a vfd to run off 115
                    or 220 single phase ) you now have a (with in sensible reason ) variable speed motor, that you can reverse at the touch of a button,go further and use the aux strip provided with the vfd and you can add controls to the machine like start stop reverse buttons, limit switches, ectect whatever


                    the vfd can be programmed to run in a number of differant ways , I have abig shaper , i run the motor up to speed graduly in case i have left the clutch out , or you can brake the motor quickly especially if you put in a braking resistor.

                    Lots written on 3 phase and vfds so look through the archives of here and PM

                    One of these days I am going change my SB9 over to 3 p and a vfd

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                    • #11
                      Hey, guys Watch those instant reverse motors on any lathe with screw on chuck. Could be a severe problem. JIM
                      jim

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                      • #12
                        I have never had a problem with the chucks on my lathe and I don't hammer them on either. The reversing action isn't as sudden as it is with a three phase motor. It's a fast deceleration/acceleration without the jolt that three phase has (without VFD). Another benefit of the instant reverse type is that they are rated for a much higher proportion of start/stop cycles than a regular motor.
                        Free software for calculating bolt circles and similar: Click Here

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                        • #13
                          Heh...someone beat me to it

                          I was going to say "it means that you can throw the switch to reverse at any time and the motor will reverse almost instantly, within less than one second."....and spin the chuck and the work off on the floor.

                          I would think that running a threaded chuck in reverse....much less instantly reversing...when you are applying force in the "remove the chuck" direction is pretty iffy.

                          No one has said *why* you would plug reverse a motor on a small lathe? I am guessing threading operations in which you don't want to pull the cutter from the thread for the next pass?? I suppose in that case, there is limited force on the work other than the initial resistance to the rotational force from the weight of the chuck.

                          Paul
                          Paul Carpenter
                          Mapleton, IL

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                          • #14
                            "instant" reverse and threaded spindle

                            I've wondered about reversing the motor with a threaded spindle. I've not tried it myself since I haven't had the need. I suppose it would be useful when threading to a shoulder and not opening the half nut.

                            The reversing action isn't as sudden as it is with a three phase motor.
                            Evan (or anyone), in what circumstance do you use this 'not-so-instant' reverse. I also have a SB9. Mine is the A model. Early '50's vintage. While I have run the motor in reverse (just to verify, yep it runs backwards alright ) I've never done so while turning something.

                            I wouldn't have a problem reversing If I were holding the work in a collet with a drawbar for example. Nothing to unscrew there. While I don't have any 3c collets I did make up a drawbar to use with MT2 collets (from my mill) and the reducing sleeve for small work. Just trying to incerase my knowledge on the subject.
                            Bill

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                            • #15
                              Instant reverse is very handy as a way to stop the lathe. You just "blip" the switch to reverse and no coast. It doesn't spin the chuck off. I have never had it happen, threaded chucks don't come off that easily (at least they shouldn't. Mine don't). The only time I have had a chuck unwind unintentionally is when backing out a stuck drill bit (large sizes). And yes, it is a very nice feature when threading.

                              If it were a major problem I don't think South Bend would have offered it. I also don't have problems threading in reverse. I also use reverse for polishing as it is safer and never have any problems. I also use reverse all the time when doing ordinary work as it can save tool changes on face end work.
                              Free software for calculating bolt circles and similar: Click Here

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