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IndustryArena Forum > MetalWorking Machines > Bridgeport Machines > Bridgeport / Hardinge Mills > Bridgeport V2xT Retrofit and lack of precision
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  1. #1
    Join Date
    Nov 2008

    Bridgeport V2xT Retrofit and lack of precision

    I am certain it has to be mechanical. So put in Hiconn BOB with closed loop to motion controller system. This a mach 4 system. problem is that I don't get same steps per inch anywhere in any of the axis' . Originally thought maybe ballscrews just sitting there for long time and no lube maybe so did this .
    problem was not cosine error with DTI. I have a problem where steps per can vary from 100,070 to 100,050 steps per inch on X axis for example.
    Here is torn X axis belt from last video. Torn about .045-.05 from edge of belt
    Attachment 471092 Here is mismatch from pulleys.
    Attachment 471094 ballscrew pulley .562" inside of the edge of that mounting box. Servo pulley almost right on the edge of plate that mounts on that face in previous picture.
    Attachment 471096. What really stinks is that I have no way of checking stretch of that belt when it is all put together. I am suspecting that I need to make 3/16" thick steel servo adapter plate instead of the 1/2" thick aluminum ones already on there. That might give me enough play so I can align my collet mounted servo axis pulley. Same situation on my Y axis, but at least there is a way to be able to measure belt stretch when it is all assembled. Now mind you the Y axis does have more stretch than it had before these servo adapter plates. Maybe that is where I am losing some accuracy. Here are pics of Y axis
    Attachment 471100 Attachment 471102 Attachment 471104
    Maybe timing pulley mismatch doing this problem or is it the stretch? Maybe something else?
    Ballscrew pics
    Attachment 471106 Attachment 471108

  2. #2
    Join Date
    Nov 2008

    Re: Bridgeport V2xT Retrofit and lack of precision

    More ballscrew pics
    Attachment 471110 Attachment 471112
    BTW, ballscrews when under belt tension ( whatever that # my be) takes less torque to move than my 1/4" click torque wrench can register. Here is pic of the sump with all the oil in it from the lubing, so I am hoping oil is getting to those screws Attachment 471114
    Any and all suggestions or thoughts are highly appreciated. My next steps will be redoing my Z axis calibration only in upward direction, some one on PM said that might help. With X axis I just bought a 22" encoder scale that will temp mount on table too see if longer than 3" moves will help. I might have screw mapping on my controller even though guys from machmotion are always telling me I don't but there is a screen on there that looks like it might just be it, so screen shoot soon to come.

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