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  1. #1
    Join Date
    Aug 2016
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    Default Hercus vibration when running

    Does anyone else with hercus 260 get vibration when running at different speeds? When I vary the speed there are some points where I get a lot of vibration coming from spindle drive, enough to shack the lathe. This is without taking a cut. The lathe is on the original stand and it's well leveled.

    Not sure of the cause yet but I guess it from unbalance pulleys or motor?

  2. #2
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    Default

    Have you checked the bearings?

  3. #3
    Join Date
    Aug 2016
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    Default

    Spindle, counter shaft and motor all spin freely. At low speed the vibration is hardly noticeable. I would say the vibration is not high frequency, more of a resonant wobble.

  4. #4
    BobL is offline Member: Blue and white apron brigade
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    Default

    Have you checked Motor with nothing attached and then systematically added other rotational components?

  5. #5
    Join Date
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    Default

    No, not yet. I'll try narrow it down tonight. I'd be interested to know if this is common problem amongst other owners.

  6. #6
    Join Date
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    Default

    Seeing that it doesn't appear to be a type of reoccurring question, I would hazard a guess and say not common, that being said 260 owners may not like sharing common faults.

  7. #7
    Join Date
    Sep 2006
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    Australind , WA
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    Default

    If a lathe has been sitting for a whle, the drive belts can develop 'knobs' where they sat on the pulleys.
    I fitted 'Link belts' to my lathe ( not a 260 ) and immediately noticed an improvement in smoothness.

    Even if that is not your problem, I'm sure you will like the change.

  8. #8
    Join Date
    Aug 2015
    Location
    Adelaide
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    239

    Default

    Do you have a VSD fitted? Sometimes they can make the motors vibrate and hum.

  9. #9
    Join Date
    Nov 2015
    Location
    Brisbane Australia
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    85

    Default

    Is the machine level?

    Where the cabinet /feet contacts the ground is the four corners supported well.

    I had it once with mine, one of the feet at the tailstock end did not have a lot of weight on it and it would move/ bounce at certain speeds.

    I bolted my stand on 100mm square tube and put adjustable feet on this.

    I wanted the lathe to be higher, I don't have "ducks disease" ( too close to the ground.)

    The concrete I have the lathe sitting on is not thick enough to bolt it to the floor.

  10. #10
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    6,439

    Default

    Hi Simon,

    My Myford cabinet, is sheet steel, it sometimes vibrates at a particular motor speed depending on how heavy a cut I'm taking. The steel backsplash doesn't help because it is fastened to the wall and sits on the drip tray lip. So when it does vibrate it get amplified by the backsplash. Unfortunately I cannot move it because it has a hole in it that sits tight around the light switch.

    The other thing is that the rubber motor mounts are deteriorating allowing the motor to move more particularly when starting. I really need to get some new ones and fit them.

    I can confirm that single phase motors do vibrate far more than three phase ones do. I've threatened for years to fit a three phase motor and VFD, I even purchased a brand new "Brooks" motor just before they shut the Huddersfield factory, so you can tell how long I've had that motor sat. Must be getting on for twenty years.
    Best Regards:
    Baron J.

  11. #11
    Join Date
    Aug 2016
    Location
    Adelaide
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    Default

    I have levelled the lathe on a fabricated platform with feet. I did it like this so I could swap the feet for casters and move it around. Perhaps the stand and platform are not as rigid as I thought they would be, but the cause seems to be the counter shaft assembly. The pulley driven by the motor has a bit of wobble. I ran the motor alone and it seemed fine. Then, the motor + counter shaft and it produced the wobble. The pulley bore and shaft fit could be tighter I think, the grub screw seems to tilt the pulley a bit. Balance might be out too. I'll start by trying to improve the alignment and balance of the counter shaft and pulleys, hopefully I can reduce the wobble. BTW, I am running a VFD.
    IMG_5606.JPG

  12. #12
    Join Date
    Sep 2012
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    Hi Monchochos,

    If there is only one grubscrew in the pulley, it might pay you to put another two in at 120 degrees from each other. If you then go round and tighten each one in turn you should find a point where the runout is minimised. It all depends upon how loose or tight the bore is on the shaft.

    If its a loose fit then the three grub screws will tend to push it straight, if its a tight bore then the pulley bore has been machined slightly askew and will need boring out and a sleeve pressing in then boring to size.

    If it still vibrates after that, then only balancing will improve it !
    Best Regards:
    Baron J.

  13. #13
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    Aug 2016
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    Default

    Thanks Baronj, good suggestion with the extra screws.

  14. #14
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    Take the chuck off and try it?
    Gold, the colour of choice for the discerning person.

  15. #15
    Join Date
    Sep 2012
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    York, North Yorkshire UK
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    Default

    Quote Originally Posted by monchochos View Post
    Thanks Baronj, good suggestion with the extra screws.
    Another thing you could check is if the bore of the pulley and rim are concentric !

    The way the counter shaft is situated on those lathes an off centre pulley will cause vibrations.
    Best Regards:
    Baron J.

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