1953 10EE MG Navy machine electrical trouble
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  1. #1
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    Default 1953 10EE MG Navy machine electrical trouble

    Hi all. As I just mentioned in a separate post about making sight glass gaskets, I just got my first 10EE (for my home shop). It is a 1953 MG Navy machine. It's not in great shape, at least cosmetically. I feel like I got a good deal, though, so don't judge it too much in the photos. I haven't fully run it yet, as I'm working through issues. I need to replace the belts and just finished flushing and replacing the various oils. However, it also has electrical problems.

    It's a 230V 3-phase machine. When I first tried to start it, the MG ran but the exciter had no voltage. It turned out (I think) to be just worn out carbon brushes on the exciter. Those have now been replaced. Now the MG runs and the exciter will allow the spindle motor to start. But the spindle motor doesn't behave properly.

    With the MG running, if I turn the spindle actuation lever (I don't know what that's called, but the lever just below and to the left of the spindle nose) to the left with the speed knob set to the slowest setting, the spindle motor turns clockwise continuously at a fairly slow speed. If I turn the spindle actuation lever to the right, the spindle motor "twitches" briefly counterclockwise and then stops. It never fully rotates. If I turn the speed knob a decent amount faster before starting, turning the lever to the left gets the spindle motor to spin clockwise slowly. Turning the lever to the right gets the spindle motor to spin MUCH FASTER but still clockwise.

    While running, turning the speed knob faster does get the spindle motor to spin faster. It also causes more sparking of the spindle motor carbon brushes and there will occasionally be bright flashes (arcing) at the carbon brushes. Also, turning the spindle actuation lever left vs. right does, in fact, cause closure of one vs. the other of the two large relays in the DC controller panel next to the spindle motor. I.e., left does one of the relays and right does the other, so I think the relays are working properly.

    Here are a few photos just to show the configuration.

    pxl_20210617_012739184.jpg
    pxl_20210617_012649057.jpg
    pxl_20210617_012657636.jpg
    pxl_20210617_012729785.jpg
    00303_cjmtmeitznoz_0ci0t2_1200x900.jpg

    Would anyone have any pointers on where to start next? I've done some Googling and can't find any useful threads that quite match this scenario. Also, I will be at work most of the day tomorrow, so please be patient if I can't reply or troubleshoot again till tomorrow after work.

    Thanks in advance,
    Josh

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    Check all the resistors are still in spec

    Nice machine , you will like it !

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    That might be a case of bad brush timing - the armature brushes on the spindle motor are mounted on a ring that allows them to be rotated. There's a balancing point where they're good for both forward and reverse, outside of that you can get all forward and no reverse, I wasn't aware that you go beyond that but maybe? Anyway, here's a search link:

    10ee brush ring timing site:practicalmachinist.com at DuckDuckGo

    You might also want to check the armature and field voltage. Field voltage can be checked with the spindle off between GF1 and GF2, spindle voltage needs the spindle trying at more than halfway between "off" and "full speed" and is measured between GA1 and GA2.

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    Thanks, guys. I'll check those things. I know the timing could very well be the issue. When I was checking carbon brush wear, I know I rotated that ring that holds them in place. I wondered why it was movable.

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    rke[pler, you're my hero. THANKS for the guidance. It was the brush timing. Using your search link, I found instructions here on basically what to do and it fixed the problem.

    For posterity sake, here's a detailed explanation of what I did:

    At the DC control panel, I found the leads A1, A2, F1, and F2 (F2 was actually two leads). I disconnected them from the screw terminals at the bottom right of that control panel. I pulled out a 120/240 to 240/480 single phase transformer I had lying around. I configured it for 120V to 480V operation. I ran 120V AC wall power to the 480V input of the transformer. I then verified the 120V leads from the transformer were putting out about 30V. I then connected these 30V leads to F1 and F2 (connecting both of the F2 leads). I connected a multimeter to the A1 and A2 leads. I tried first with a cheap multimeter I had most handy. On its lowest AC voltage setting (200V), I could see that rotating the DC motor brush bracket would give me 0.0V over a broad range of orientations. I knew that wasn't going to be accurate enough. So, I pulled out a different multimeter that had a 2V AC range. With it set on that and connected to the A1 and A2 leads, I rotated the brush bracket until I got the lowest voltage (0.011V). I then tried to tighten the bolt to lock the bracket in place. Then I discovered someone in the past had intentionally put a washer between the bracket halves preventing the bracket from being tightened. In reading some of the posts in rke[pler's search link above, apparently at least one other person has run into that before. I removed the washer, tightened the bracket, and it fixed the problem.

    Yay! Now it runs quietly without surging or visible arcing over the entire speed range in forward and reverse. It seems to be about the same speed in forward and reverse. I don't have the drive belts on yet, so I haven't verified the speed is the same or that the max tach speed is reached, but it seems like it.

    New (dumb) question: what is the proper operation of the forward/reverse lever? Mine goes forward when I move the lever left and reverse when I move the lever right. That seems counterintuitive to me. Nevermind: I figured it out and it is running the proper direction. Now I'll go put the belts on and start playing with it...

    Thanks again for the help, guys!

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    Going off memory here, but I think the drum switch itself is pretty standard and you could rewire it so the lever does what you want, ex lever to the right can be CCW or CW
    depending on your tastes.

    Quote Originally Posted by paroikoi View Post
    rke[pler, you're my hero. THANKS for the guidance. It was the brush timing. Using your search link, I found instructions here on basically what to do and it fixed the problem.

    For posterity sake, here's a detailed explanation of what I did:

    At the DC control panel, I found the leads A1, A2, F1, and F2 (F2 was actually two leads). I disconnected them from the screw terminals at the bottom right of that control panel. I pulled out a 120/240 to 240/480 single phase transformer I had lying around. I configured it for 120V to 480V operation. I ran 120V AC wall power to the 480V input of the transformer. I then verified the 120V leads from the transformer were putting out about 30V. I then connected these 30V leads to F1 and F2 (connecting both of the F2 leads). I connected a multimeter to the A1 and A2 leads. I tried first with a cheap multimeter I had most handy. On its lowest AC voltage setting (200V), I could see that rotating the DC motor brush bracket would give me 0.0V over a broad range of orientations. I knew that wasn't going to be accurate enough. So, I pulled out a different multimeter that had a 2V AC range. With it set on that and connected to the A1 and A2 leads, I rotated the brush bracket until I got the lowest voltage (0.011V). I then tried to tighten the bolt to lock the bracket in place. Then I discovered someone in the past had intentionally put a washer between the bracket halves preventing the bracket from being tightened. In reading some of the posts in rke[pler's search link above, apparently at least one other person has run into that before. I removed the washer, tightened the bracket, and it fixed the problem.

    Yay! Now it runs quietly without surging or visible arcing over the entire speed range in forward and reverse. It seems to be about the same speed in forward and reverse. I don't have the drive belts on yet, so I haven't verified the speed is the same or that the max tach speed is reached, but it seems like it.

    New (dumb) question: what is the proper operation of the forward/reverse lever? Mine goes forward when I move the lever left and reverse when I move the lever right. That seems counterintuitive to me. Nevermind: I figured it out and it is running the proper direction. Now I'll go put the belts on and start playing with it...

    Thanks again for the help, guys!

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    Thanks for the pointer, Maxim. I'm fine with the default way it works now that I know it's correct. I appreciate the info, though.

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    Quote Originally Posted by paroikoi View Post
    Yay! Now it runs quietly without surging or visible arcing over the entire speed range in forward and reverse. It seems to be about the same speed in forward and reverse.
    This is what you WILL get when trying to use "static" timing rather than dynamic.

    For best performance and longest brush life, I time them "live" such that FWD has the least spark.

    That gives about a 10% RPM advantage to FWD when run unloaded. But IF.. "FWD" is what you use the most?

    It can greatly extend the brush life and deliver more power.

    Double glove. Use insulated tools.

    Timing at full Voltage is HAZARDOUS!

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    Quote Originally Posted by thermite View Post
    Timing at full Voltage is HAZARDOUS!
    That's the reason I did "static" timing. I think it worked pretty well. I had a decent amount of sparking beforehand with intermittent bad arcing. Now I don't see any spark at all. I cringe thinking of how I initially cleaned the commutator with a stone with it running fairly fast. I was wearing nitrile gloves, but had no idea just how high the DC voltage could be. I prefer to not electrocute myself.

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    Quote Originally Posted by paroikoi View Post
    That's the reason I did "static" timing. I think it worked pretty well. I had a decent amount of sparking beforehand with intermittent bad arcing. Now I don't see any spark at all. I cringe thinking of how I initially cleaned the commutator with a stone with it running fairly fast. I was wearing nitrile gloves, but had no idea just how high the DC voltage could be. I prefer to not electrocute myself.
    Nitrile is right fragile. I like tile-setters fabric-in over Nitrikle, then Pigskin or flexible Deer or goat, over.

    Proper power utility "linemans" glove sets can be purchased economically.
    The "inner" is meant to stop current passage. The outer, to prevent rips and tears to the inner. Which one tested for pin-hole leaks "back in the day" by blowing them up, balloon-style.



    More to it. "It's an Industry", so info is all around yah, online.

    Stoning a ommutator wth two 12 V auto batteries in series is still up for over 100 VDC spikes on circuit disconnect.

    More better to belt-drive the UNPOWERED DC motor from an external motor.

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