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How to remove spindle bearings on HF General Machinery 12x36 lathe

Discussion in 'HARBOR FREIGHT, CENTRAL MACHINERY & BUSY BEE' started by 703906, Aug 27, 2017.

  1. 703906

    703906 United States Swarf Registered Member

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    Hi all! I've had my 12x36 General Machinery lathe since 1998 and it really hasn't needed much maintenance in all this time - one motor replacement and a switch. But now it is making coffee grinder sounds intermittently, and sometimes runs smoothly but a little while later, without having moved the work piece, there's suddenly runout. I suspect the spindle bearings, but I have been completely unable to remove the spindle in order to replace them.

    What I've done is remove the cover over the left end of the main shaft, and then the tensioning nut that squeezes the left bearing. I removed any set screws I could see on the main shaft gears, as well as a key. I also removed the four bolts that hold a heavy duty frame around the spindle on the right. According to Youtube videos I've looked at, but which were not about my specific lathe, it would appear the main shaft is now ready to be pounded out from left to right. I tried that with a mallet and it moved a quarter inch. I tried with a heavier object and no luck. Ditto using a threaded rod. The thing just won't budge beyond a quarter inch and I'm afraid to escalate the force any further.

    I'll attach the manual, which on page 18 has a drawing that shows the spindle and the gears on it.

    Any pointers would be more than appreciated, I've been fighting this thing literally all day and am utterly stuck.

    Thanks,
    Alec
     

    Attached Files:

  2. Bill W.

    Bill W. United States H-M Supporter - Premium Content H-M Supporter-Premium

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    Alec...
    Welcome to the HM "club". Are any of the items besides #19 , (maybe #'s 12 & 15) threaded on the shaft?
    If it only moves a quarter inch, something else must be keeping it from moving. That's kind of a DUH.. statement...huh?
    It just seems to me that something more than #19 would provide pre-load on the bearings.
    Anyway... again, welcome to the forum and I'm sure someone with more knowledge than myself will be along to help.
    Good luck. Bill W.
     
  3. 703906

    703906 United States Swarf Registered Member

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    THANK YOU!!! It was a "duh" indeed, but had escaped me because the thread was concealed by the nut and the nut didn't look like a nut. I only discovered that's what it was when looking at the description of the individual parts (#12). Now the interesting thing is that having been able to inspect the bearings and their runs, I found them looking perfect. Maybe this needs a little more tension, or maybe the noise is coming from somewhere else. I'll keep digging.
     
    Bill W. likes this.
  4. markba633csi

    markba633csi United States Active Member Active Member

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    Looks can be deceiving, but you could re-assemble and re-set the bearing preload and run it for awhile. A good test is to put a long bar in the chuck
    and pull on it to get a feel for the error. Write down the bearing numbers so you can shop around for prices.
    Mark S.
     
  5. Silverbullet

    Silverbullet Active Member Active Member

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    You could have another spot causing the problem. You feed box qcgb or the drive shaft bearings on the feed screw lots of ways the problem could show up. All it would take is a gear bearing gulling and hanging up. Just my thoughts.
     

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