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IndustryArena Forum > MetalWorking Machines > Haas Machines > Haas Mills > Unpowered Z axis lowering ( discharge the counterbalance)
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  1. #1

    Unpowered Z axis lowering ( discharge the counterbalance)

    Hey yall. we recently purchased a VF-2B and its time to move it. the machine in not currently powered and has no real way to get it powered. we are trying to sort out how to get the spindle down to the table with the least amount of trouble and or damage. discharging the enough nitrogen from the counterbalance tank seems like a reasonably easy way to get it done. i can recharge with out much trouble back in out shop with a accumulator charging set up . Is the the best way to accomplish this or is there a better way ?>

  2. #2
    Join Date
    Nov 2007
    Posts
    1699

    Re: Unpowered Z axis lowering ( discharge the counterbalance)

    Does it even have a counterbalance? What year is the machine?

    Even if it does, there's a fair chance that the pressure will already be low. The Z axis motor does 100% of holding up the head on machines after at least 2003-2004. I understand there's a brake in there that locks when it loses power. That holds the screw against back-driving.

    I would put a floor jack on the table and raise it up to the spindle. Pump a little pressure under the spindle to support it. Next, get up on top and remove the Z axis motor. Do not do this without the spindle supported at the bottom. As soon as that motor comes off, there will be nothing holding up the head except the nitrogen cylinder (if you even have one). Lower the spindle to rest on a block of wood. Preferably, get a spindle support bracket and screw everything together.

    The spindle support bracket doesn't only keep the head safe but, it also keeps the table from moving around during transport. Hit the brakes hard and it may not take much for the table to overcome the ball screws and slam into hard stops or the ends of the screw travels.
    Greg

  3. #3
    Quote Originally Posted by Donkey Hotey View Post
    Does it even have a counterbalance? What year is the machine?

    Even if it does, there's a fair chance that the pressure will already be low. The Z axis motor does 100% of holding up the head on machines after at least 2003-2004. I understand there's a brake in there that locks when it loses power. That holds the screw against back-driving.

    I would put a floor jack on the table and raise it up to the spindle. Pump a little pressure under the spindle to support it. Next, get up on top and remove the Z axis motor. Do not do this without the spindle supported at the bottom. As soon as that motor comes off, there will be nothing holding up the head except the nitrogen cylinder (if you even have one). Lower the spindle to rest on a block of wood. Preferably, get a spindle support bracket and screw everything together.

    The spindle support bracket doesn't only keep the head safe but, it also keeps the table from moving around during transport. Hit the brakes hard and it may not take much for the table to overcome the ball screws and slam into hard stops or the ends of the screw travels.
    This machine is an early 2003. Im not positive if it has a counterbalance or not. I had read that it could have is why is was tracing that option down. I had also read that you take the z motor off the tool high change is effected. Is this true .

  4. #4
    Join Date
    Nov 2007
    Posts
    1699

    Re: Unpowered Z axis lowering ( discharge the counterbalance)

    Yeah, I really don't think a 2003 has the counterbalance anymore. It's not rocket science. Is there a giant nitrogen tank and gauge on the side of the casting? It's not like you're going to miss it. It's on the same side as the tool changer between the cabinet and the electronics.

    And if you take off that Z axis motor without supporting the spindle, the entire head will drop and slam into the table like a rock. Make absolutely sure you have it supported and have control over it before the motor comes loose.

    No, nothing about the tool height is going to change. The machine finds its home switch every time you power up. You can put the motor back on mid-travel, power it up and it will jog up to the Z limit switch just like it has always done.
    Greg

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