Problem with the new lathe

Discussion in 'The Shop' started by Johno1958, Mar 9, 2017.

  1. Mar 9, 2017 #1

    Johno1958

    Johno1958

    Johno1958

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    My sc4 I received just before Christmas has started playing up.
    [ame]https://www.youtube.com/watch?v=vM_kHyYAqd0[/ame]
    The problem sounds very mechanical but it all turns over very smoothly by hand.
    It is bring up ERR. error on the screen. This is an intermittent fault as other times it runs OK. I googled the fault and came up with this link.
    http://www.modelenginemaker.com/index.php?topic=6336.msg129474#msg129474
    I have contacted the Australian distributor and he said to check the wiring as it can get jolted out of place during transit. So I checked and tightened connectors.
    Has not made a difference.So I'll be doing a warranty claim.
    Just thought I'd post this in case any other sc4 lathes develop the same problems.
    Cheers
    John
     
  2. Mar 9, 2017 #2

    bazmak

    bazmak

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    No problems so far with my sc4 touch wood but thanks for posting
    I had similar problems with my sc2 .The control panels are too complicated
    for most of us.Supplier may change boards for you,but its not something
    you can send back for repair.This one of the major faults with the modern
    vario speed benchlathes.No such problems with Myford etc.Keep us posted
    I sold my sc2 as is and bought the sc4,would do something similar if it happened again
     
  3. Mar 10, 2017 #3

    kiwi2

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    Hi John,
    As you say the problem certainly sounds like it's mechanical. The source of the noise sounds like it could be associated with the cover on the left hand side of the machine (it sounds like something knocking on light gauge steel).
    There are a couple of things that can go wrong with the gear train which could cause the controller to trip out due to a current overload.
    One thing to try is to loosen the quadrant holding the gear train in place and rotate it so the gear train is not engaged. If the lathe operates OK then I guess that's where the problem lies.
    It would probably pay to take the cover off the top of the headstock and have a look inside as you start it up to see if anything obvious is going wrong there as well.
    Another thing to try is to disconnect the motor drive belt and see if the motor will work under no load.
    I hope you can figure out what's wrong.
    Regards,
    Alan C.
     
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  4. Mar 10, 2017 #4

    wheeltapper

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    I have one of these and it sure sounds like something banging on the cover.
    the only thing under the top cover is the gear pair that engage and disengage the spindle, make sure the front knob is either full engaged or disengaged or the gears could rattle together.
    watching the video, I can't help wondering why you are pushing the speed control button with the lathe not running, push the start button first, then change speed.


    Roy.
     
  5. Mar 10, 2017 #5

    Johno1958

    Johno1958

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    My bad, I did not explain properly.
    I had already hit the start button and it took that long to start. I have already removed belt from the motor and couldn't start it so its down to the motor or controller . The motor turns over by hand nice and smooth. This is a very intermittent fault as it can run smooth for all day then then loose torque
    rattle ,stall ,or throw up an error and not start and I can turn the lathe over easily with with two fingers either way. Any way I'm taking more video's this time with the drive belt disconnected and send them of to where I bought it from.
    Cheers
    John
     
  6. Mar 10, 2017 #6

    Johno1958

    Johno1958

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    Just had another play with it.
    Belt disconnected from motor.
    [ame]https://www.youtube.com/watch?v=nGN-FLwK9E4[/ame]

    Got it going after a while. Lot of noise.
    [ame]https://www.youtube.com/watch?v=gfPJapfjsZg[/ame]

    Started and stopped a few more times.Running sweeter .
    [ame]https://www.youtube.com/watch?v=lcbl_HOvDEY[/ame]

    Just after I finished filming it went bang and ran rough again.It would be better for me if it went bang and that was the end of it.
    cheers
    john
     
  7. Mar 11, 2017 #7

    kiwi2

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    Hi John,
    I guess there's not much doubt it's an electrical/electronic problem. Your best bet might be to go back to the supplier with the videos and get them to query Seig. I doubt your problem is unique and they should be able to identify what the problem is.
    Regards,
    Alan
     
  8. Mar 11, 2017 #8

    rodw

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    I've had similar problems with my Seig Mill when it was new. The solution was to tighten every screw connector in the wiring and remove every plugin connector and clean with Inox lubricant which is electrically safe. Its been good as gold since!

    I still get the ERR if I overload the mill but pressing the stop button and restarting it fixes it.
     
  9. Mar 12, 2017 #9

    Johno1958

    Johno1958

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    Yes have now done that Rod and still no go. If I let it stand with the power on
    for 30 mins before I try to start I may get some movement out of the motor.If it's cold ,not much happens so something is cactus. I've sent the videos of to the supplier as they though it was a mechanical fault as I did at the start but I think they are willing to send out a new control board now the mechanical side of the lathe has been ruled out .
    Fingers crossed.
    John
     
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  10. Mar 12, 2017 #10

    blanik

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    John,

    It might be a silly question, but ...... have you tried turning the motor over by hand with the power turned off ? I just took the belt off my SC4 to see what the motor felt like, and it rolls over silky smooth, and if I apply a radial load to the motor pulley, there is no discernible free play in the pulley end bearing.

    If your motor doesn't turn over freely and smoothly when turned by hand with the belt removed, and/or you can detect any radial free play in the bearing, I'd suspect that you have one or both motor bearing that has failed. A failed bearing that has excess radial play would allow the rotor of the motor to touch the stator (field windings formers).

    If the motor was running when the rotor touches the stator, you'd hear that awful metallic noise, and worse as the bearing continues to deteriorate. Many many years ago when I worked as an apprentice Electrician, we used to say that an electric motor was "polling" when bearing wear was allowing the rotor to touch the stator or field windings.

    The circuitry that drives Sieg's brushless DC motors includes overload protection for the motor. That overload protection disconnects power from the motor in the event of an overload (i.e. something jamming the lathe or motor), and on the SC4, it displays the Err message, requiring the lathe to be switched off completely to reset the Err message.

    If the rotor is touching the stator of the motor when the motor is stationary, the motor control circuitry would probably detect an overload when the motor was turned on. The motor would be prevented from running, and the Err message would be displayed. You could test that by switching the motor on, and if it doesn't start to turn immediately, give the motor pulley a flick with your finger (or a chicken stick if there's a chance of getting your finger caught in the mechanism).

    If the motor bearings have failed, and the rotor has been contacting the stator when the motor is running, there is probably much internal damage to both the rotor and to the stator; so simply replacing the bearings will probably not be enough of a fix. I think you'll probably be up for a new motor under warranty.

    Let us know how you get on.

    Regards,

    RoyG
     
  11. Mar 12, 2017 #11

    Nick Hulme

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    Call it a night, hit the turps and sling in a warranty claim, it's clearly rooted!
    :D
     
  12. Mar 13, 2017 #12

    Johno1958

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    Motor has got no play and turns over smooth except ripply sort of feel like a stepper motor, but that's it for me ,they can fix it.
    John
     
  13. Mar 18, 2017 #13

    pepi

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    I agree, mess with it too much and the OP will end up getting blamed.

    Greg
     
  14. Mar 18, 2017 #14

    Ken I

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    That "ripply" feel is indicative of some sort of problem - sounds like a permanent magnet (PM) motor with an armature winding short - could be as little as a single loop - but it plays havoc with the VFD. The motor fails to vector smoothly and sounds can vary from the delicate tinkling of tumbling broken glass to a cement mixer filled with scrap iron.

    If it is a PM motor then you can test drive it with a cordless screwdriver (effectively driving the PM motor as an alternator) and measure the three output phase voltages (disconnected from the VFD for this test) one phase will be low - there's your problem.

    You might also have a phase short.

    P.S. edit - if the "ripply" feeling goes away when disconnected from the VFD - then the problem is in the VFD.

    If it's a squirrel cage rotor then none of the above apply and I'm baffled.

    Regards,
    Ken
     
  15. Apr 12, 2017 #15

    kiwi2

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    Hi John,
    How did you get on? Did you have any joy from the supplier?
    Regards,
    Alan
     
  16. Apr 12, 2017 #16

    XD351

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    From what i can see it is a brushless motor so maybe the problem is in the switching transistors of the motor driver , it could be just a bad solder joint causing one of the dc phases to work intermittently or not switch polarity fast enough to keep up with the other phases .
    Its a bit like having a brushed motor running and then slamming it in reverse then back into forward at high frequency .
    Either way it is covered by warranty so the seller should fix it and if you are not familiar with mains voltages or circuit boards that work at those voltages i wouldn't go poking around one as there are usually some capacitors that could be still charged to mains potential and can stay charged for a long time after the machine has been unplugged from the power socket .
     
  17. Apr 13, 2017 #17

    Johno1958

    Johno1958

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    Yes that is my thought as well that one of the phases is dropping out .
    It's apparently a servo motor.
    Anyway parts are suppose to be on the way.
    Cheers
    John
     
  18. Apr 13, 2017 #18

    XD351

    XD351

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    If they haven't asked for the faulty board back set it up next to the new one and check the solder joints on both boards , if any look dry or incomplete it may be worth re soldering them before fitting the new board and then keep the old board for a spare and if you spot something that looks like a dodgy solder joint on this board give it some attention with a soldering iron .
    Just watch out for those charged electrolytic capacitors - they will bite ya !
    If you can , please take some photos of both boards so we can take a look at them and others who follow can compare with their boards etc .
     
  19. Apr 13, 2017 #19

    DJP

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    Good idea to compare two circuit boards as often I have found engineering changes implemented with an additional component or two soldered on top. It's then easy to upgrade the failed board and have two working again.

    Worst case, if there are discrete components save the old board for donor parts. The machine needs to run for a lifetime or two and shouldn't be abandoned in the future because of failed electronics which is usually what happens.

    Another easy test is to look for swollen capacitors. This seems to be a common failure point these days and easy to fix.

    Since re-soldeirng every wire connection and replacing the speed control pot, my mini-mill has been reliable. I don't worry about it anymore and the project to re-power with a treadmill motor is on the shelf.
     
  20. Apr 14, 2017 #20

    Johno1958

    Johno1958

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    Thanks guy's.
    If they allow me to keep the the dud board I'll take it into work for the sparky's to have a look at. I'm a robotic and automatic guided vehicle operator so the fellows at work may have an idea.
    Cheers
    john
     

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