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IndustryArena Forum > MetalWorking Machines > Bridgeport Machines > Bridgeport / Hardinge Mills > Bridgeport Series 1 Rigid Ram spindle speed off by 50%. ???
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  1. #1
    Join Date
    Nov 2009
    Posts
    77

    Bridgeport Series 1 Rigid Ram spindle speed off by 50%. ???

    I just checked the spindle speed with 2 different digital tachometers and found 3251 rpm when the dial said 2200. I can see a little off, but 50% under-reporting? Is this normal or is there a way to calibrate the dial? Probably can't calibrate the dial, because all I could do is add rpm, not multiply. Could this be due to a worn belt that is orbiting at a different radius on the cone pulleys, now?
    cnc1000

  2. #2
    Join Date
    Apr 2005
    Posts
    175

    Re: Bridgeport Series 1 Rigid Ram spindle speed off by 50%. ???

    This attachment might help. If speed is off by the same amount at all settings, then you need to adjust dial. Belt wear , would only show as a small change. Also make sure that the speed increases when you press the increase button as the chain can be on the wrong side of the gear (when you go to far the one way)

  3. #3
    Join Date
    Nov 2009
    Posts
    77

    Re: Bridgeport Series 1 Rigid Ram spindle speed off by 50%. ???

    Good info. Thanks. I will have to modify it, though. I have the pneumatic speed control, btw. If I run it up to 4200 rpm, I'll be temporarily making the machine turn vastly faster than it's designed to do. Hence, I think it would be best to adjust it at 2200 and get it to read 2200, and only then, crank it up to 4200 and check it.
    cnc1000

  4. #4
    Join Date
    Jan 2005
    Posts
    1121

    Re: Bridgeport Series 1 Rigid Ram spindle speed off by 50%. ???

    I doubt it will go much faster than designed, unless the motor is twice speed. There isn't that much room on the pulleys

  5. #5
    Join Date
    Apr 2005
    Posts
    175

    Re: Bridgeport Series 1 Rigid Ram spindle speed off by 50%. ???

    The lub pump plunger is activated when the spindle turns on and stops when spindle stops. The original system used those low voltage contacts on the top of the MF/MR relay. You will also have to look at this system of running in respect to the mist/flood coolant. You will want the coolant to stop running when the spindle turns off and on when spindle starts. This can , and is done in gcode, but if working correctly, once the coolant is decided to be used, you do not have to turn on and off by code as it will be modal.

    In respect to your speed changer. I realize that you have a pneumatic control, but this is just an air motor that runs cw and ccw. This in turn, tightens or loosen a chain that adjust the lever at the vari-drive. If the air motor is rotated in one direction to far, the chain will wrap around the gear on the otherside and make the system work In reverse. Since you rewired the airmotor control switches, you might have the switches reversed as to function, but think it is correct as it adjust the speed but maybe it is not. Usually the speed on the dial is close to correct, not out by a lot. You could press the up button till it goes over center and continue till the dial starts to turn. You may need to press the down button as we do not know if it is correct. Then check speed of spindle to dial.

  6. #6
    Join Date
    Nov 2009
    Posts
    77

    Re: Bridgeport Series 1 Rigid Ram spindle speed off by 50%. ???

    Thanks to your info sheet, I adjusted the speed calibration bolt and it's spot on, now. The air motor will go one way but very reluctantly the other. Someone suggested a clogged air filter up there on the solenoids. The air motor acts like it is sluggish.The previous owner said some bushings may be wearing out, preventing easy sliding of the pulleys (I assume). Suggested I make some, but isn't there somewhere that sells parts like that for these old beasts?
    cnc1000

  7. #7
    Join Date
    Apr 2005
    Posts
    175

    Re: Bridgeport Series 1 Rigid Ram spindle speed off by 50%. ???


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