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Thread: Ball screw

  1. #1
    dodge_99 Guest

    Default Ball screw

    I'm new in my shop where I work. And have helped change 3 ball screws in the last 2 weeks. They are Mori-Seiki machines when we putting on the nut on each end the just tighten the up snug. I asked if there should be some kind of torque spec. on the. They say they just snug them up tight. What I want to know is there a torque spec. on a ball screw or some other way to do this. I just think my tightening of a nut is going to be different from some one else and so on. Any info. would be great.
    Thanks

  2. #2
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    Dodge_99,

    I always do this, put an indicator in the end of the ball screw do see the gap, move the axis to + and - direction and tighten the nut to this value is less then 0,02 mm. I know that has an specific torque, but ???

    Daniel

  3. #3
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    Xavierdemoura is right in how he checks it. Which should be done as a final check in installing a ball screw always. It checks that there is no float in the screw when moving back and forth. The way I usually set it is basically hit the nut till it sounds solid. As long as the nut goes on very free to begin with you will notice a huge sound difference as you tap the nut tight. You will notice the captured end gets tight very quickly and when you hit the other end to stretch the screw you can here it little by little become more solid. Once you have stretched the screw and taken up all the backlash the sound when tapping on the nut should be solid. It may be hard to here it in a loud shop sometimes but as you do them double check with an indicator as Xavier.. suggests. Make sure you move back and forth quickly to put the most load on the ball screw and check for float.
    Programming is like ***: one mistake and you have to support it for the rest of your life

  4. #4
    chad Guest

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    Sammy is right though for someone new he failed to mention you always capture the driven end of the ball screw. Also when stretching that depends alot on the length of the screw. On an some machines with say a ten foot screw length the stretch is very significant but on a smaller lathe you will not see that screw stretch as much. But as Sammy stated if you do not have any motion in and out on the floating end of the ball screw with a tenths indicator then you have installed it correctly. Most companies I have found will give you the specs for the torques. Sometimes it is in the mechanical drawing notes. It is a good idea to get these as some manufacturers specifiy that you should loctite bolts or set screws during installation.

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