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??1941 Bridgeport Mill??

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  • ??1941 Bridgeport Mill??

    My mill is giving me trouble. I just installed a servo type 150 in x axis feed unit. When i bought the mill it was all apart. The old guy told me just grab that screw and nut and stick er together. He says its better to buy em all apart so you know how to fix em. Oh i says. $1900 bucks i paid for it and learned how to move machinery to boot. (call crane company) anyhow i dont think its the right ballscrew and it has lots of backlash to boot. Im thinking of replacing the screw nut with a superior unit. Perhaps future cnc conversion??? My question is what do i do to get the right replacement part?? The serial number is 370 and is a step pulley model. I hear bridgeport is no longer around. Any good parts sources in Ontario Canada you might know of??? Thanx Guys.

  • #2

    Is the play in the shaft mounting bearings or in the nut? The nut should be split to provide adjustment for part of the wear in the nut and on the shaft.



    • #3
      Bridgeport is now part of Hardinge, , although that may not help you any.
      Try to make a living, not a killing. -- Utah Phillips
      Don't believe everything you know. -- Bumper sticker
      Everybody is ignorant, only on different subjects. -- Will Rogers
      There are lots of people who mistake their imagination for their memory. - Josh Billings
      Law of Logical Argument - Anything is possible if you don't know what you are talking about.
      Don't own anything you have to feed or paint. - Hood River Blackie


      • #4
        "anyhow i dont think its the right ballscrew and it has lots of backlash to boot. Im thinking of replacing the screw nut with a superior unit."

        Ballscrew??? You lost me here. Where did the ballscrew come from? 1941 B'ports didn't have ballscrews.


        • #5
          I've read somewhere that you get a second chance with the nut on a bridgeport ..
          first over the years you get to adjust the lash out of it with the normal nut ....

          then later on the nut can be sawn in half or something ...and you get another run out of it .

          I could be mistaken ...but others will say.

          All the best.mark


          • #6
            ??1941 Bridgeport Mill??

            All of the Bridgeport tables I have ever been into had bronze threaded bushings that the lead screw threaded through. The bronze nuts had a saw cut across them about 3/4 of the diameter, and a cap screw that ran parallel to the lead screw in the body of the nut. To tighten the lash out you simply tightened the cap screw a little and it put a little bind on the screw threads.

            Obviously, the ball screw setup is an aftermarket fix. I am sure that anyone who sells ball leadscrews can furnish the correct set if you give them that S/N to go by. As for removing lash from ball screws, I have no idea and no personal experience with them. I would hope that there would be some straightforward adjustment for them.

            good luck with your dilema.
            Jim (KB4IVH)

            Only fools abuse their tools.


            • #7
              The standard feed nuts have a slot cut most of the way through. You can (theoretically) use them without cutting the slot through further, but you are then trying to compress a big brass nut with a small adjustment screw.

              Better bet is to remove the nut, complete the cut with a bandsaw or hacksaw and then clean up the "mating faces" in the lathe and re-assemble. Then, the adjusting screw is merely squeezing the "two" new nuts together in their bore. This not only allows for more adjustment, but also easier adjustment.

              Still, wear them enough and they need replaced and are available from many of the BP replacement parts places. Alternative machine tool is one that comes to mind. I've bought parts from H&W in Indiana and gotten good advice as well. One of the proprietors (H of H&W) was very helpful and has been in the rebuilding business for many years.

              One thing to watch for if you have *loads* of backlash is to make sure that the adjustment bolt for these nuts has not backed itself completely out. I had that on mine when I got it. There is a locking screw for the adjusting screw that was gone, and probably allowed the adjustment screw to disappear.

              Manual mills pretty rarely have ballscrews installed and never from the factory that I know of.

              Was there a problem with the power feed that you believe is caused by the feed nut?

              Paul Carpenter
              Mapleton, IL