What is allowable play in Babbitt bearings on a lathe spindle?
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    Default What is allowable play in Babbitt bearings on a lathe spindle?

    I have started working through the 1904 LeBlond I just acquired and observe .0015 play in the back bearing, and .0042 in the front. This seems extreme in the front, but what is acceptable?
    My only experience with poured Babbitt is in my 1929 Model A, and those bearings are smaller in diameter, better lubricated, and running at much higher speed (but run at .0015 clearance).

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    Do some searching using the terms "babbitt spindle bearing clearance".

    Babbitt Bearings & Oil Film Thickness? is a place to start, the link at the end of that thread is excellent for real engineering information (but likely more than you need).

    I agree with you that the front clearance is too much.

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    Does it have any shims under the bearing cap? If not, maybe a good idea to put some in for next time.

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    Do you have a 48" lathe or a 14" lathe. I think .001" clearance for a 14" lathe is good and go up from there.

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    More important to me...

    Turns freely by hand

    Does not heat much at all at top speed

    I guess that equates to as little as possible clearance

    It is after all a precision machine tool, not a wheelbarrow

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    Quote Originally Posted by Milland View Post
    Do some searching using the terms "babbitt spindle bearing clearance".

    Babbitt Bearings & Oil Film Thickness? is a place to start, the link at the end of that thread is excellent for real engineering information (but likely more than you need).

    I agree with you that the front clearance is too much.
    Too much engineering information? That must be some sort of oxymoron!
    I have done some design of hydrostatic and hydrodynamic bearings, but at the low rpm and low flow of oil in this spindle I cannot count on the generation of a proper oil wedge.
    .0005" per in. of shaft diameter sounds about right. I will pull the bearing caps and see what I have... Perhaps I get lucky and the bearing is split and shimmed, and I can just adjust the shim stack.

    And it is a 17" lathe with a 3" shaft. So scaling from the 14" lathe gets me close to the .0015" resulting from the .0005" per inch guide.

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    Are you having problems with the quality of work the lathe is producing? If its not broke don't fix it.


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