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VFD on a Clausing 4800 for low speeds

Discussion in 'CLAUSING-COLCHESTER & BANTAM' started by Enderw88, Jul 16, 2017 at 5:24 PM.

  1. Enderw88

    Enderw88 United States Iron Registered Member

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    Yesterday I busted a tooth off of the bull gear. Unfortunately it was right next to a tooth that was missing when I bought the lathe. From what I can tell I am more likely to win the lottery than find a good condition bull gear. I read up on some methods of repairing it but none of them really inspired me with confidence.

    I really don't like the idea of trying to thread things without the back gear. I am considering adding a VFD/3-phase motor to use in place of the back gear. I understand about being down on power at lower speeds, but on the back gear I am usually just threading which should require lots of grunt. Are there any other drawback anyone can think of? Or, am I wrong about not being able to find a bull gear?
     
  2. wa5cab

    wa5cab Downloads Moderator Staff Member H-M Supporter-Premium

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    You should at least call Clausing and find out whether or not they still have the gear and if so for how much. Personally, in a case like this I'd bite the bullet and ignore how much it cost. If you put a VFD on the machine (which might be worth doing for other reasons) about the slowest that you can run it is 1/3 the standard motor RPM which for 3.phase will usually be 1800. Below that, the motor will rapidly overheat. At 600 RPM, your slowest RPM will be 64, twice the slowest RPM in back gear.

    As far as finding a used one, I don't know the odds, but not as good as it would be if the machine were an Atlas, because not as many of them were made.
     
  3. machPete99

    machPete99 United States Iron Registered Member

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    Concur with Enderw88. I have 5914 which I converted to VFD (no countershaft) but still use the back gear a lot.
     
    Last edited by a moderator: Jul 17, 2017 at 8:23 PM
  4. RWL

    RWL United States Active User Active Member

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    I cut my first gears last winter to help out a neighbor whose Rockwell lathe had a couple of broken change gears. It wasn't all that hard. If you have a torch capable of brazing, build up some bronze where the tooth broke off and cut a new tooth. Technically the tooth cutting could be done on your lathe, and it wouldn't take a dividing head, just some way to index the teeth on the existing bull gear. The gear cutter would be on an arbor in the lathe. The bull gear would be mounted horizontally on the compound rest and fed in by the cross slide. You would need a series of spacers of increasing thickness to lay the bull gear on to raise it with regard to the gear tooth cutter. It would be a lot easier if you have a friend with a mill and a dividing head or a friend with a shaper. Of course, the easiest route is to find a used bull gear with all its teeth and buy that if it's reasonably priced.
     

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