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Thread: Post Drill, cracked down-feed thrust bearing

  1. #1

    Post Drill, cracked down-feed thrust bearing

    Hello everybody ~

    I'm fixing up a Buffalo No. 61 Post Drill and have a question for the machinist types. Any guidance would be much appreciated. Pics are attached.

    The lower end of the up/down feed screw connects and transfers thrust to the top of the drill spindle through, apparently, a single pair of fixed ball bearings. One bearing is set into the lower end of the feed screw and one bearing is set into the upper end of the spindle.

    The ball bearing the top of the spindle is cracked about in half, and the ball bearing on the lower end of the feed screw is worn flat-ish. Neither ball bearing spins and I suspect they were never meant to. Without any real load, the up/down feed operates smoothly despite the cracked bearing. I'm holding off on any real use, pending the advice of my betters.

    Questions are: How can I fix this? How did those bearings get in there in the first place? How to extract and then properly replace? I'm a reasonably competent mechanic and have access to a metal shop, but is this a repair that requires a pro or specialized equipment?

    Thank you much for reading and considering. May thee and thine be well ~ thom. k
    post_drill_61.jpg
    spindle_bearing.jpg
    feed_screw_bearing.jpg

  2. #2
    Join Date
    Sep 2016
    Location
    Modesto, CA, USA
    Posts
    3,975
    Are you sure they are balls and not a dowel? They may be floating in the holes and held in by grease for assembly so they do not fall out. I would think about drilling them out and replacing with a bronze shaft or ball. Or maybe lay a bronze washer over them. Just a little thicker then the ball sticks up.
    Bill D

  3. #3
    Join Date
    Sep 2009
    Location
    Putney, Vermont
    Posts
    809
    I may be off here, but those bearing balls don't look like they would take much pressure and I am not sure they are intended for that purpose.

    Have you pushed down on the balls and seen if they are spring loaded an any way? If they are spring loaded could they have been meant as access for lubrication?

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