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Bridgeport replacement working well

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  • Bridgeport replacement working well

    I recently got this 1982 vintage Alliant 42VC with factory fitted ProtoTrak Plus 2-axis CNC control to replace a 1961 Bridgeport that was worn beyond practical use. I paid $100 more for the newer machine than did the old one some 12 to 15 years prior.

    This to this:

    And today I got the pocketing cycle figured out.

    Double the HP I had, none of the slop in the ways, more speed (up to 100ipm feed, 4200 rpm), and with one-shot lube that works. Life is good!

  • #2
    Still a Bridgeport though....... sigh.

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


    • #3
      Marginally better than a Bridgeport, John. The previous owner is a 25 year old whiz (and I mean unbelievable skills) who took apart the head and added support bushings and bearing upgrades to the variable speed drive. The Meehanite base of the Alliant is substantially heavier than the Bridgeport. Ball screws on the table and saddle are at least 25mm diameter. How is this less worthy than a Blidgeport?


      • #4
        Looks like a good swap too me!

        The Prototrak Plus Control,is it a full featured CNC control,or does it mainly do canned cycles?
        I just need one more tool,just one!


        • #5
          Originally posted by wierdscience View Post
          Looks like a good swap too me!

          The Prototrak Plus Control,is it a full featured CNC control,or does it mainly do canned cycles?
          Just getting into it after over 30 years with Fanuc, Yasnac, Cincinnati, Seimens, Mitsubishi, Siemens and other oddball controls, I'd have to say that it's "so simple it's hard." It has canned cycles of sorts for Mill, Drill, Pocket/Frame, Arc and Circle. It can be used in "Power Feed" mode, similar to having a 6F feed box on a BP. A "Do One" cycle does something I've not explored yet.

          The seller says he's got a seat (license) for BobCAD 25 that he's going to give me, and that a customizable post processor can be configured to output "ProtoTrak" codes. That is what I really need given my background and the kind of tool paths I want to be able to run. I believe the post would output short versions of the canned cycles. You can use the control keypad in "Mill" cycle to string together multiple events, such as a Mill to an Arc, and it will carry a tool radius compensation offset through the path if done right. If nothing else, the control works fine as a 3-axis DRO under 100% manual hand cranking.

          So far, I've found that if you go in an edit an existing program, it may drop some field values in the canned cycles. Because of that it becomes necessary to dry run the program over the work to see if the path appears to be what you want.

          All told, it's a helluva lot better than the clapped out machine it replaces.


          • #6
            Congrats on the new machine PixMan!
            Some of those type of controls have what they call a "teach" mode where you can hand crank it point to point, making an entry at each point. This records the toolpath which can then be run in auto mode. That may or may not be the "Do One" cycle.
            There may be a mode for 3D manual hand cranking which is usually used to verify a program without crashing the machine since it only moves when you do. If you want the machine to stop, you stop.
            Kansas City area