Older round ram Bridgeport mill with M-head
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  1. #1
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    Cool Older round ram Bridgeport mill with M-head

    This may be a very simple question, but I assumed I knew the answer before when I first got my mill and saw what I believed to be grease zerks on the table, knee, etc. and thus lubricated all of them with a large amount of grease...only to discover I was not to use grease at all, but rather oil. After learning this I ended up spending the time to completely remove the table, cross slide and knee and cleaned out all of the oil passages. That was a big job I'm here to tell you.

    My mill has the M-head with a 1/2 HP motor; at the top of the motor is a zerk. I am assuming this is to provide lubrication to the motor, do I use grease in this zerk for the motor or is it supposed to be oil??

    This is a 3-phase motor and when running it this afternoon I noticed the outside of the motor was getting very warm, almost hot. I felt up by the top of the motor and it didn't feel hot, it was actually cooler than the side of the motor.

    I ended up shutting down the mill until I could determine what to lubricate the motor with.

    So, what should I put in the zerk located on the top of the 1/2 HP motor???

    Thanks in advance for the information!!

    Rick

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    Oil. Don't use grease anywhere.

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    Quote Originally Posted by Holescreek View Post
    Oil. Don't use grease anywhere.
    Even on the motor? Just clarifying. I'm pretty sure others have used grease, that may be the issue then.

    Looks like I'll be pulling the motor and tearing out apart to clean it up. Oh boy!

    Sent from my SM-G973U using Tapatalk

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    Hold up here ! Determine what type of bearing you have. Oil is normally only used on sleeve/plain bearings. Ball/roller bearing normally are grease. I'll bet $5 to a donut that motor has ball bearings. Vertical shaft motor would not be a good place for oil. Every place else ie ways that have Zerks DO get oil only. Try Vintage machinery for a period correct lube chart for that old round ram.

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    Is the mill motor 3 phase? Its dead simple to break then motor case open and get to the bearings. You can wash them out and reinstall or just replace.

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    Quote Originally Posted by Ohio Mike View Post
    Is the mill motor 3 phase? Its dead simple to break then motor case open and get to the bearings. You can wash them out and reinstall or just replace.
    Yes, 3-phase, 1/2 hp

    Sent from my SM-G973U using Tapatalk

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    Quote Originally Posted by medic29 View Post
    when running it this afternoon I noticed the outside of the motor was getting very warm, almost hot. I felt up by the top of the motor and it didn't feel hot, it was actually cooler than the side of the motor.
    By all means sort your lube issue, bearings too, if need be. No dog in that exercise.

    Meanwhile.. be aware that:

    40C / 104 F would be considered "cool", very, for a typical electric motor.

    70C / 158 F (above human "scald" temp) not at all unusual.

    Light/moderate use for any significant run-time? I'd expect about 55 C ~ 130 F.

    .. and that when fan-cooled, the intake/fan end WOULD be cooler.

    IOW.. the temps you report - where you can still touch without risk of burn - sound more "normal" than not.

    The heat does not - ordinarily - come from bearing friction, will not vanish even if bearings are perfect. It is from eddy currents in the Iron & Copper, plus modest losses in the imperfect conversion of electricity to motion. Characteristic of "real-world" motors. JFDWT.

    Mind.. I haven't run a "round-ram" BeePee since summer of 1963, but I don't recall ever being motivated to fondle the motor in any case.

    It just isn't located where one has much of a frequent need to do.

    And that's a feature, not a bug!


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    I use my round bar BP M1 mill weekly for small projects. I converted the 3 phase to accept an ABB VFD and 220 single phase. I added a small break resistor (radiator) to control the motor with a heat sink plate behind the knee. My motor does not exceed 130 degrees F even after continuous run. This is just my take. I did open the motor and clean it when i first purchased the unit 8 years ago and on occasion i blow out the motor with air to clean the belt residue

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    Quote Originally Posted by thermite View Post
    Meanwhile.. be aware that:

    40C / 104 F would be considered "cool", very, for a typical electric motor.

    70C / 158 F (above human "scald" temp) not at all unusual.

    Light/moderate use for any significant run-time? I'd expect about 55 C ~ 130 F.

    .. and that when fan-cooled, the intake/fan end WOULD be cooler.

    IOW.. the temps you report - where you can still touch without risk of burn - sound more "normal" than not.

    The heat does not - ordinarily - come from bearing friction, will not vanish even if bearings are perfect. It is from eddy currents in the Iron & Copper, plus modest losses in the imperfect conversion of electricity to motion. Characteristic of "real-world" motors. JFDWT.


    @Thermite I had the opportunity to check the temp on the outside of the motor when I went to turn it off. The highest temp I got was 247 F. I'm thinking it shouldn't run that hot. If this is normal, please advise.

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    Too hot. My 1hp J head is usually less than 100 deg.F. never more than 130F. What are you powering the motor with? When I first got my mill I had a cheap static phase converter. The motor got a little on the warm side but I didn't suspect the converter until I got a VFD and it runs very cool. Is the belt slipping?

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    Quote Originally Posted by medic29 View Post
    @Thermite I had the opportunity to check the temp on the outside of the motor when I went to turn it off. The highest temp I got was 247 F. I'm thinking it shouldn't run that hot. If this is normal, please advise.

    That sort of temperature may well indicate a turn-to-turn fault in the windings. But before you panic over that, take the motor apart. Not too difficult, just take it off the head, then undo the bolts holding it together, and check that it hasn't got grease all over the place. If so, then clean it up with Varsol/kerosene and reassemble. If one part of the windings is visibly blackened, then take it to a rewind shop.

    Generally speaking motor ball bearings only need greasing every decade or so and with a fairly small amount of grease. It's far more common to see them over-greased than under-greased (cost my boss £25,000 on a backup generator rotor!)

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    I took some time this afternoon to take the motor off my Bridgeport and take it apart. I may have discovered what was causing it to smoke. The following are some pictures of the motor once I got it off the machine.

    Exterior of motor pictures
    Motor 1
    Motor 2
    Motor 3

    Top and bottom removed
    Inside bottom of motor
    Inside top of motor

    Viewing the bottom of the motor with case removed
    Looking at bottom of motor 1
    look at bottom of motor 2
    look at bottom of motor 3
    look at bottom of motor 4

    Viewing the top of the motor with the case removed
    look at top of motor 1
    look at top of motor 2
    look at top of motor 3

    The rotator
    Rotator 1
    Rotator 2
    Rotator 3

    The Stator
    Stator 1
    Stator 2
    Stator 3

    I’m thinking this motor has been way over-greased and that may be the cause of why it was smoking. Do you think this could be the cause of the heat?? I got a high temp yesterday of 247F. Now the next question, what is the best way to clean all of this grease off the motor? I used some mineral spirits to clean the rotator and part of the stator.

    The windings look like they are covered by something like a hard plastic or similar. Whatever this is, is hard to the touch and not pliable. I didn’t see any evidence of melting or anything which has burned, but with it being black it is hard to tell.

    The bearings seemed okay, but since I have it apart should I go head and replace them with sealed bearings so as to not repeat the over greasing issue in the future? If I do this I could remove the grease zerks and plug the holes or just leave them open as they wouldn’t hurt anything. I’m leaning towards replacing the current bearings with sealed bearings.

    Thoughts???

    Rick

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    Quote Originally Posted by Ralph_P View Post
    Too hot. My 1hp J head is usually less than 100 deg.F. never more than 130F. What are you powering the motor with? When I first got my mill I had a cheap static phase converter. The motor got a little on the warm side but I didn't suspect the converter until I got a VFD and it runs very cool. Is the belt slipping?
    It is 220v 3-phase running off a static phase converter. So you're saying the phase converter can make the motor run hot??

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    Quote Originally Posted by medic29 View Post
    It is 220v 3-phase running off a static phase converter. So you're saying the phase converter can make the motor run hot??
    A static isn't a "converter" and what you get is NOT "3-Phase".

    All it does is provide an initial phase-imbalance to kick the motor off in the desired direction of rotation- instead of sitting still, locked and humming loudly..

    It then runs it on single phase at full power to one of the three "per phase" winding sets. That gets you about 1/3 of "nameplate".

    The motor itself then induces "some" power in the other two windings, similar to the way an RPC's idler does. That gets you a tad above 1/3 if the load is not heavy. Bit less, actually, since the motor wasn't built to be run that way. Count on about 30%, pretty much reliably. The next 30% a struggle, and anything above 60% seriously bad news.

    Heat imbalance is unavoidable. Ruined motors can happen. Online photos will show you examples with one winding set burnt.

    Doesn't work as well power-delivery wise as a separate idler, either, because ... the motor is NOT "idling" but is instead also trying to support a shaft LOAD, if/as/when it IS under load.

    When NOT loaded? Less of a challenge.

    Odds are your uneven heating problem goes away if you but add a 'real' idler and make a few other minor changes to convert your "static" to an RPC starter/controller. A "ROTARY" Phase converter does far the better job of balancing uneven heating. Good for 90% or so of OEM nameplate, sustainable, not just peak. Mind . it will also WASTE some of the power it draws, too. Relative"merit" vs native 3-Phase is lower.

    The greater the load, the more obvious the difference.

    OEM maker of your "static" one probably provides the specs and how-to info for doing that add-an-idler upgrade/conversion?

    Not hard.

    First, just "borrow" an existing 3-Phase motor and try it. In the simplest form it is simply switched-on parallel to the M-head motor, as-in on the same outlet or junction box.

    Making it cleaner, neater, and more permanent can come later.
    Last edited by thermite; 12-08-2021 at 08:53 AM.

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    Quote Originally Posted by medic29 View Post
    The bearings seemed okay, but since I have it apart should I go head and replace them with sealed bearings so as to not repeat the over greasing issue in the future? If I do this I could remove the grease zerks and plug the holes or just leave them open as they wouldn’t hurt anything. I’m leaning towards replacing the current bearings with sealed bearings.

    Thoughts???

    Rick
    Gross. Parts washer is the appropriate way to clean it. Sealed bearings, or just grease it on an appropriate call. You're the one doing the maintence. If you prefer to grease is a long interval schedule, open, or if you prefer to replace bearings, sealed.

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    Quote Originally Posted by medic29 View Post
    I took some time this afternoon to take the motor off my Bridgeport and take it apart. I may have discovered what was causing it to smoke. The following are some pictures of the motor once I got it off the machine.

    Exterior of motor pictures
    Motor 1
    Motor 2
    Motor 3

    Top and bottom removed
    Inside bottom of motor
    Inside top of motor

    Viewing the bottom of the motor with case removed
    Looking at bottom of motor 1
    look at bottom of motor 2
    look at bottom of motor 3
    look at bottom of motor 4

    Viewing the top of the motor with the case removed
    look at top of motor 1
    look at top of motor 2
    look at top of motor 3

    The rotator
    Rotator 1
    Rotator 2
    Rotator 3

    The Stator
    Stator 1
    Stator 2
    Stator 3

    I’m thinking this motor has been way over-greased and that may be the cause of why it was smoking. Do you think this could be the cause of the heat?? I got a high temp yesterday of 247F. Now the next question, what is the best way to clean all of this grease off the motor? I used some mineral spirits to clean the rotator and part of the stator.

    The windings look like they are covered by something like a hard plastic or similar. Whatever this is, is hard to the touch and not pliable. I didn’t see any evidence of melting or anything which has burned, but with it being black it is hard to tell.

    The bearings seemed okay, but since I have it apart should I go head and replace them with sealed bearings so as to not repeat the over greasing issue in the future? If I do this I could remove the grease zerks and plug the holes or just leave them open as they wouldn’t hurt anything. I’m leaning towards replacing the current bearings with sealed bearings.

    Thoughts???

    Rick
    As Murf said, "parts washer".

    (AND NOT "brake cleaner", carb cleaner, or any other of the harsher solvents!)

    Basically "mineral spirits" are not supposed to harm the varnish on the windings nor Glyptal or other brand of equivalent baking varnish.

    Of which there are black ones (as Glyptal, but not-only) also brighter red, in the "basics", plus yellow, blue, green speciality ones.

    But your one seems to be BBQ'ed grease! I'm lazy enough I'd replace it rather than clean it except for the fact it is a scarce motor type, and not as cheap and easy to replace as the common types my machines use.

    The windings DO need to be free of baked-on grease to be able to transfer heat, not impede its escape.

    A motor is otherwise OK at heat that would give human skin "scald" level skin damage.

    Here's a useful explanation:

    https://www.machinedesign.com/automa...or-temperature

    Note toward the end he mentions dropped-phase or "single-phasing" as an effect that can burn-out a motor. Exactly what a "static" converter-NOT does if used long enough and/or hard enough. Be happy when an idler is added, early-on and saves the motor that slow death.

    Or settle for not liking European motors in any case. They tend to be more highly stressed / over-optimistically rated.

    BFD. I got the lathe more cheaply, enjoyed throwing the static converter in the garbidge, and prefer a US Made Reliance or even a Brazilian Weg motor anyway!


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    I got some time out in the shop today and worked on the motor from the mill.

    This is what the bottom looked like when I split the motor apart.


    Look at the pile I removed from that bottom part.


    This is what the inside of the bottom looks like now.



    The top half wasn't near as bad initially.


    Here it is now.



    Then there was the rotator


    It cleaned up fairly well
    https://www.rrogers.us/Bridgeport%20...212_161913.mp4


    I've decided to go with sealed bearings and am waiting for them to be delivered. Once they arrive I'll get them installed, then get the motor put back together.

    I have also ordered a rotary phase converter from American Rotary and I will begin using it instead of the static phase converter.

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    Looking good. That's gonna work fine.

    Tell us about that purdy lathe.

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    Sorry so late on this thread, been away from the PC

    I had the same issues with my old mill.
    First, I was using the static converter that was given to me and it did result in very hot motor and smoke. I only used it long enough to make the mounts for my VFD, shutting it down when I could smell it. Since I installed that it has purred and never gets over room temp.
    Second, my US Motor has plates telling me to pump grease thru the top and bottom zerks until the it pushes all the old grease out of the plug hole once a year. I use blue electric motor grease.


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