Z axis counterbalance noise
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  1. #1
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    Default Z axis counterbalance noise

    After getting tired of groaning jerking noise on the z axis, I changed the ballscrew and linear guides, expecting a fix. Not so, apparently the less than 1 year old counterbalance is making this noise. It only makes it the last 6” or so of the lower z travel.

    The machine is a 96 vf2 with the well known nitrogen over oil counterbalance.

    Is this typical? It seems like an alignment issue would exhibit itself in the upper axis when the rod end is closest to the cylinder.

    I fully expected the z axis to be moveable and to try to move up when the ballscrew was out, but there was no way I could move it by strong arming it. The z servo load seems to run a fair bit higher as well.

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    Dredging this up, I'm still dealing with this. I'm finding that the counterbalance is quite warm to the touch. Has anyone else seen this type of issue? Its annoying to hear the machine groaning when rigid tapping and drilling, as it typically sounds worse at less than 40 ipm or so.

  4. #3
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    I have a '97 with the same CB, if you're sure that's the issue then perhaps you could block up the head, bleed the compressed gas to "0", then decouple the shaft and try moving it up and down on its own.

    You might have to drain the oil too, that would be a good time to inspect it for metal or other contaminants. If the cylinder shaft is very sticky it may require a rebuild (if possible) or replacement. I have no idea if Haas still has the cylinders in stock or whether a modern equivalent will have to be adapted.

    Any chance of getting some video/audio of the issue? My '97 started making a noise at one section of travel near the table that could be the same as what you've had. I also suspected a worn ballscrew (figuring that part which sees a lot of motion during peck drilling would wear first), but now you've got me wondering. I am comfortable that it's not the rails.

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    Thanks for that vid! It's not the same sound as mine, which comes and goes depending on how long the machine's been running and where in the range Z is moving. I'll try to take my own video when I have that machine running again.

    When you did your replacement of the ballscrew and rails, did you double-check the oil feed lines and flow? I've seen cracked lines and lost flow due to buildup of paraffins from the Vactra oil that used to be recommended.

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    I'm not sure, I think I did though. Everything is and was well lubed. This noise doesn't seem to get worse with time, and so far there is no leak. This noise is somewhat worse in the lower ranges, but not in any particular spot.

    I've been using vactra, what is the real scoop on that?

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    Quote Originally Posted by friesen View Post

    I've been using vactra, what is the real scoop on that?
    I don't have immediate references, but I've read that the Vactra formula had too much paraffin solids in it that could precipitate out and clog lines and filters. I've noticed in the past solids that had built up in the 5gal containers if V.2 that I'd bought, and that's caused me to worry about it even before I read of the change in recommendation.

    There was a thread recently on lube schedules for Haas machines: Haas spindle motor grease zerks / motor bearing lubrication type

    With the recommended way lube now Mobil SHC 625 or even Mobil 1 5W-20.

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    are you talking about that banging noise? I dont hear anything else?

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    No, it's more of a sqeal noise, double pitch on the way out.


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