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  1. #16
    Join Date
    Aug 2010
    Location
    Toorloo Arm, VIC
    Age
    39
    Posts
    1,270

    Default

    I know it's a bit late, but in putting my mill back together I had a brainwave on how the bull gear lube system works. Typical of a Bridgeport, the idea is crudely simple.

    The large bull gear takes up most of the housing in diameter, but when in high there is a lot of space under it. In high it doesn't need any grease at all, as it's not running on anything.

    The trick comes in the sufficient packing of the housing. If you fill all of the space underneath the large bull gear, when you select low gear it squishes all of the grease underneath out of the way as the large bull gear drops down - which extrudes around all the teeth, and migrates to the top side of the large bull gear.

    When you go back to high, the sheet metal cover on the top squishes all the grease back past the large bull gear to the underside again.... Currently my high/low selector goes squelch, squelch as you change between the two

    The design makes perfect sense if you consider the basic concept of the Bridgeport - it's intended to run predominantly small cutters, and I guess the designers envisioned that low gear would only see occasional use. Thus, every time the user selects low, the teeth get regreased simply by that action.

    The practical outcome of this is that if you spend all of your time running in low gear, you'd definitely be better off running something more liquid like a steering box grease, as the grease will indeed sling off over time. Or if you're doing a long run in low gear, pause every now and then to cycle the lever from low to high and back to low again to get a fresh dose of grease on the teeth.

  2. #17
    Join Date
    Aug 2008
    Location
    Charlestown NSW
    Age
    65
    Posts
    1,669

    Default

    Funnily enough, I came to a very similar conclusion. .
    I also remembered that I had some oil/grease (consistency of room temperature honey) left over from an overhead crane gearbox refurb that I was involved in some time ago. So I used that. Worked on the idea that when its in high the small gear is submerged in this goo and when its changed over to low, the gear come up out of it and spreads some on the bull wheel.
    I also fixed the spindle lube system whilst I had it apart. The original oil cup had an extension pipe inside the head that ended just inside the housing, nowhere near the spindle. I relocated the oiler so it lined up with the axis of the spindle and extended the pipe so the oil actually drips onto the felt washer at the top of the quill.
    Fitted an open bearing at the top instead of the shielded listed on the parts diagram.
    Now the oil actually runs through and eventually drips out the bottom. So for the first time in its life the bottom bearings are actually getting some oil.
    The oil dripping out would bother some people, but not me. I have to keep the table and all the other bare metal oiled to stop rust anyway, so I just spread it around.

    You can see the relocated and longer oil pipe at the bottom left of the picture. Also the extra oil pipes I fitted to oil the quill feed gears etc

    oil pipes.jpg

    peter

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