motor shaft repair

  1. johnser

    johnser Member

    Messages:
    2,121
    Location:
    North Cornwall
    Turns out it will fit in the lathe (just - with 2" of the tailstock overhanging) and there is a centre each end, one was full of gunk. But I've put the front in the 4jaw rather than on a centre - it was a bit out - plus, I'd have had to make a drive dog to fit.

    Makes space a bit tighter but still ok to turn down the worn bit - down from 40mm to 39.35 diameter before it was cutting cleanly. Hopefully that's within the scope of one of those crush rings.
     
    arther dailey and 8ob like this.
  2. Hopefuldave Intergalactic pot-mender

    Messages:
    1,804
    Location:
    The Shed of Danger, surrey, England
    I'd be surprised if the motor shaft hasn't got a centre in the end from when it was first made - assuming some animal hasn't mullered it with the BFH...

    Dave H. (the other one)

    OOPS - didn't see the last post....
     
  3. johnser

    johnser Member

    Messages:
    2,121
    Location:
    North Cornwall
    This motor is 30-50 yrs old. Many animals have pounded on the end I suspect. Including this animal. The key steel was something round and pointy, jammed in place. That said, it was only running ~0.06mm out.

    It'll be a nice old motor if I can get it going again though, it's built like a tank.
     
  4. Agroshield Member

    Messages:
    1,367
    It's not the unworn-ness of it that is important. You have to find or make some part true before welding that will also stay true after welding.

    The technical info. from Euro-bearings has all the necessary measurements in it:

    https://www.euro-bearings.com/TOLRINGS.pdf

    But if you are doing weld build up inboard of that centre, there is no guarantee it will remain true after welding. You do your weld repair, set it back up on the lathe using a steady on the immutable bit and then recut the centre. Remove the steady and use the new centre for truing up the welded bit.
     
    johnser likes this.
  5. johnser

    johnser Member

    Messages:
    2,121
    Location:
    North Cornwall
    Yep, plenty of shaft left for a wrinkly washer. That's the first thing I'll give a go.

    I see your point regarding having a reference pre-post welding, hopefully won't come to that.
     
  6. Brad93

    Brad93 M J B Engineering

    Messages:
    10,394
    Location:
    Essex
    Speedi Sleeves are generally only for the bearing seals no?

    Edit: see you were talking about the crush rings. Not used them myself, but if they work you might as well use them.

    Some Loctite Bearing Fit compounds can take up to 0.5mm of slop out.

    Personally, I would weld it with MIG or TIG.
    Stick is great but smaller shafts will quickly become heat soaked, And then there is spatter and slag to deal with.

    MIG, dip transfer, 17-19V, 4-6.5m/min. I’d set it up on a turntable, but you can run straight lines down the shaft if that makes you happy. Distortion doesn’t really matter if you’re turning all the weld down.

    The best solution in my opinion is metal spraying.
     
  7. Turbo Member

    Messages:
    3,846
    Location:
    Fermanagh, Northern Ireland
    I think I would be looking for a bearing with the next size smaller inner diameter & machine the shaft to suit. I've seen those tolerance rings used in KEW and Karcher pressure washer motors from new & they always cause trouble, especially when they get hot. Try to stay away from welding if you can, if the shaft warps you will be in a new world of pain!
     
  8. johnser

    johnser Member

    Messages:
    2,121
    Location:
    North Cornwall
    That would mean reducing the size of the shaft and new keyway. Aside from the extra hassle, I can't do either of those things here. So, least cost/destruction will be a tolerance ring, then try welding.
     
  9. johnser

    johnser Member

    Messages:
    2,121
    Location:
    North Cornwall
    Thanks for all the help everyone, turned the shaft back to within the required tolerance and use a tolerance ring. Seemed to accept the bearing with a nice snugness so hopefully it'll run for a decent while. All back together anyway.

    Certainly glad to have learnt about another option.

    Cheers.
     
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