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9" Atlas Lathe Motor Wiring

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  • 9" Atlas Lathe Motor Wiring

    The 1/4 HP Westinghouse motor that came with the 9" Atlas lathe given me had been removed and wires cut, apparently for ease of moving. Looks old with a heavy iron case so I assume it to be original. There are four leads: removing the terminal cover I can see there are two ports from inside the motor, one above the other, with a pair of wires passing through each. The wires are old, and insulation frayed where they had passed through the terminal cover (guess I'll have to tape those as getting inside the motor to rewire looks a little scary). There is no discernable color coding to the wires. There are also two old fashioned binding posts, not connected to anything. The lathe has a reversing drum switch, so I assume this is a reversable motor. I'd guess each pair was a hot and neutral for each direction, but of course I don't know.

    My first objective is to determine if the motor works, but was hesitant to test connect the leads by trial and error . Does anyone happen to know the wiring connections of this motor? I'd be glad to post a photo if that would help. And eventually I hope to find a wiring diagram for that reversing switch. And suggestions where I might locate one?

    Thanks alot!


  • #2
    The following is based on your description, that it is a split phase or capacitor start, and on the idea that it worked when it was cut loose. If that was wrong, this may not even apply...................

    Two wires are "run" winding, two are "start". There is a switch that should disconnect the start with a 'click" when it starts uip. You should hear it close again as it slows down also

    get an ohmmeter, or rig one with a battery and light.

    Find two wires that have continuity. separate them.

    Then connect one of the other two to each of the first pair.

    At this point you should have two pairs of wires, and they should have continuity through from one pair to the other, with "some " small amount of resistance.... i.e. they should NOT be "shorted" to each other. A 1/4 HP motor could have an ohm or two....

    There should be basically NO continuity to the motor case..... it should be in the megohms (millions of ohms).

    At this point, you may try the motor with 120V.

    If it works and rotates the right way, you are probably good, if it does not overheat when run for some time, nor draw more than about 40% or 50% of full load current as marked.

    if it rotates the wrong way, reverse the connections of the "second" pair of wires found above. That should reverse it.

    If it was me, I would do more testing, but I have the equipment.....

    If the above puzzles you, get someone who knows motors to look at it. Electricity is actually not difficult to deal with, but it is dangerous. If you mess up, you can be electrocuted.

    Oil it..... all motors are happier when bearings have oil........

    If you decide you want to use the reversing fature, all that is needed is to set up a switch (the drum switch works) to reverse one of the two pairs of wires.

    You will have to let it come to a stop before reversing. Most single phase motors (with one or two obsolete exceptions) won't "plug reverse" like a 3phase.
    Last edited by J Tiers; 12-30-2006, 12:05 AM.
    CNC machines only go through the motions


    • #3
      Who you calling obsolete??

      Seems to me that motor could be in the same class as the one on my SB9. It might just instant reverse. I am not even sure what makes an instant reversing motor do that on single phase but mine sure does.
      Free software for calculating bolt circles and similar: Click Here


      • #4
        SB had that option. It should be a "repulsion" type motor.

        There are "repulsion", "repulsion-induction", and "repulsion start induction run" types.

        The first two IIRC will plug-reverse if properly wired.

        Not obsolete? Try to buy one off the shelf new!

        I doubt strongly if an atlas 9" has one of the above..... always possible, hence the disclaimers.

        Internet advice is always fraught with problems.

        Even if the person giving it is an expert (and many are not.....) then still they are dependent on the description presented by the person asking.....

        If you have ever been on a jury, and watched the attorney questions and witness responses crossing at 90 deg to each other, you'd immediately understand.

        Or if you work retail with anything technical.......... as Evan has, and I have.

        So it is completely possible that the motor is nothing like my (or your) mental picture.....
        CNC machines only go through the motions


        • #5
          The motor on my SB9 is a 1/4 hp Westinghouse with four wires coming out of it to the drum switch. The wires aren't color coded either but have brass ferrules crimped on them labeled T-1, T-2, T-3 and T-4. Not especially informative but given the age of your lathe and mine (1937) they are very likely similar motors. Chances are that it may be instant reversing but you need to identify what wire is which. On mine there are three grometted holes in the cover. Two of the holes have just one wire exiting, the other has a pair.

          Put up a photo of the name plate on the end of the motor so I can see if it is anything like mine. If it is I will make some measurements tomorrow and try to figure out the wiring of the switch for you.
          Last edited by Evan; 12-30-2006, 01:10 AM.
          Free software for calculating bolt circles and similar: Click Here


          • #6
            The instant reverse type IIRC reverse one of two windings much as you would for a "universal" motor (they will instant reverse also).

            And, the windings may not be parallel for such a motor.

            If it IS an instant reverse, please disregard my description..... as explained, that is assuming an induction motor.

            What does the nameplate call it?

            BTW................look and see if it has brushes and a commutator..... if so, it may be like Evan's.

            If no brushes, it is probably a standard induction motor. That is pretty definite if you can see a start switch in there, or a capacitor in a case on top of it....
            Last edited by J Tiers; 12-30-2006, 10:46 AM.
            CNC machines only go through the motions


            • #7
              Photos of motor

              Here are a couple hotos I took today of the motor today.

              I hope they will provide more clues.



              • #8
                Another idea is like I do if I am not shure of what I am doing . Take it to one of the local motor repair shops around town with a box of hot donuts ,they will usually check it out for free and show me how to wire it to my switch so it will run like I wont it to. Havent payed for a motor check up yet and I have had 30 are 40 motors ckeck out over the course of years . One place even re wound one for me on a dumore tool post grinder in their spair time and only charged for the wire. so check out your local motor repair shops.
                Last edited by lane; 12-30-2006, 09:44 PM.
                Every Mans Work Is A Portrait of Him Self


                • #9
                  That unfortunately, doesn't look anything like the motor on my South Bend. I don't think they are similar after all.
                  Free software for calculating bolt circles and similar: Click Here


                  • #10
                    Evan: thanks, it was worth a try.

                    J Tiers:

                    1. there is no external capacitor

                    2. short of splitting the case, I can't see if there are any brushes.

                    2. I have a digital VOM, and an Amprobe, and will conduct the tests you suggested. I'll report back what I find. Thanks.



                    • #11
                      Those wires look nasty.....

                      The two little screws or nuts on each side of that plate should allow you to gain access to the internal connections.. and replace the wires.......

                      But, it is possible that the whole end bell has to come off, not clear from photo.

                      I am hoping the "screws" are slotted nuts that hold the plate, with more nuts under that hold the actual end bell......
                      CNC machines only go through the motions


                      • #12

                        we are having a similar discussion at on a chinese motor with links..

                        ie: how a start capacitor motor works.. is explained in detail. If you understand how something works, you can usually figure out a problem.

                        Thier factory drawing is wrong, the 120 hookup is wrong, the switch hookup is wrong, the motor was wired 220 and sold.

                        Pretty much two sets of coils on the two sets of wires. one set is start windings, other set is run windings, as long as the start winding phase orientation is swapped.. the motor will reverse at start up. the phase lag-is accomplished normally by capacitor.. this delays full energization and delays decay for milleseconds offsetting the phase wave of the alternating voltage. Shifts the phase over slightly allowing a lead direction to be established. or simply reversing motor.
                        Excuse me, I farted.


                        • #13
                          Originally posted by J Tiers
                          Those wires look nasty.....

                          The two little screws or nuts on each side of that plate should allow you to gain access to the internal connections.. and replace the wires.......

                          But, it is possible that the whole end bell has to come off, not clear from photo.

                          I am hoping the "screws" are slotted nuts that hold the plate, with more nuts under that hold the actual end bell......
                          I agree . . . if the tests you suggested prove the motor is operational, I'll work on removing the end bell to replace the wires. I don't see any seams but it has to come apart somehow. The two (female threaded) screws on either side of the wire ports held on a cover over that area . . . I just threaded them back on so I wouldn't misplace them. I assume if I remove all 4 screws on that end something will come loose . . .

                          Wonder what those two binding post terminals are for??

                          The nameplate is riveted on.


                          • #14
                            Paul, if it was me, I would do as I did: take it to a local electric motor repair shop, pay them a few bucks, and have the peace of mind that it was figured out by some fellows that knew more than I did. This was a 1943 1/4 HP motor off my 1943 Montgomery Ward lathe.


                            • #15
                              Originally posted by Paul_NJ
                              2. short of splitting the case, I can't see if there are any brushes.
                              How about that plate which is visible in the photo of the end housing? The plate which covers the lower half. Two screws hold it on. That's where the brushes would be if it was something goofy like an induction-repulsion motor. But if it was the nameplate would most likely say so.

                              Here is a photo of a Westinghouse Type CAH (not mine).

                              It shows the wires hooked up in what looks like an ordinary way for a split-phase or capacitor start motor. Even though no capacitor is visible it may still be a capacitor start motor. The capacitor on the oldies was sometimes inside the end housing. More modern capacitor start motors have an obvious lump on the side so we can usually identify them at a glance. A split phase motor has no capacitor at all. It relies on winding resistance for the phase shift - an inductive/resistive time constant rather than a capacitive/resistive or capacitive/inductive one.

                              When wiring it up you don't care if it's capacitor start or split phase. You have to get current to the main winding, and current to the start winding. You swap the start wires around to reverse it.

                              When facing a real mystery motor I just make my best guess as to what's what with the ohmmeter, then connect it momentarily. If it doesn't start right away (like, half a second or less) I disconnect it and try something else. With 4 wires there aren't too many ways you can go wrong. If you take it to somebody else to do it, you won't learn anything about motors.