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  1. #1
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    Pros and Cons of Using Dual Z Axis Drive

    I haven't seen too many examples of this configuration and I was just wondering why?
    Is it too complex, not overkill?
    On first thougth, it seems to have alot going for it, besides the cost of extra components.
    The spindle mount would be very simple with the minimum of overhang and one could have a longer Z axis to allow for higher jobs.

    Have I missed something obvious?....

    I hope to be building a T Slot Router one day and I would like to know if this is a viable option.
    Your thoughts?
    Steve

  2. #2
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    Re: Pros and Cons of Using Dual Z Axis Drive

    Interesting idea....not something i would do

  3. #3
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    Re: Pros and Cons of Using Dual Z Axis Drive

    Why?..too complex and/or expensive?

  4. #4
    Community Moderator ger21's Avatar
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    Re: Pros and Cons of Using Dual Z Axis Drive

    Pro's and Cons depend on what you are comparing it to. A single spindle machine, or an ATC machine.

    Pro's:
    If most of your work only requires 2 tools, then it's much faster than a single spindle machine, and even an ATC machine.

    It's slightly to a lot cheaper than an ATC, depending on the ATC spindle you choose.

    Con's:
    You need two of everything.
    Two leadscrews. Two sets of linear rails. Two spindles. Two steppers or servos, and two drives. Two VFD's*.

    It's twice as heavy.

    It's bigger, requiring a longer gantry.

    Chinese ATC's can now be found for as low as $1500, but when you add toolholders and everything else you need for an ATC, you'll usually be at about $3000 or more.

    A dual Z axis can be done for less than $1000.
    Gerry

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    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  5. #5
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    Re: Pros and Cons of Using Dual Z Axis Drive

    Quote Originally Posted by Sterob View Post
    Why?..too complex and/or expensive?
    I guess it's because i like to keep things simple....not saying it's bad cause i have not looked into it. I just did not ever consider doing something like that

  6. #6
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    Re: Pros and Cons of Using Dual Z Axis Drive

    Quote Originally Posted by ger21 View Post
    Con's:
    You need two of everything.
    Two leadscrews. Two sets of linear rails. Two spindles. Two steppers or servos, and two drives. Two VFD's*.
    .
    Sorry, I tried to find a pic of what I was thinking about but couldn't find one.
    My idea was to raise and lower the Gantry with a stepper at each end of the gantry instead of raising and lowering the Spindle.
    One spindle and one VFD.

    But you are correct....twice as many linear rails , ball screws, steppers and drivers.......



    and still have dual Y axis as well...lol


    Steve

  7. #7
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    Re: Pros and Cons of Using Dual Z Axis Drive

    I have a feeling i might build a big machine in the near future....something that can handle full sheets..2.4 x 1.2 m

  8. #8
    Community Moderator ger21's Avatar
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    Re: Pros and Cons of Using Dual Z Axis Drive

    Oh, I thought you meant dual spindle, but you're talking about a gantry that moves up and down.

    Not sure any benefits would outweigh the cons. Much more weight to move up and down, and more money. And the only benefit is more gantry clearance?
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  9. #9

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    Re: Pros and Cons of Using Dual Z Axis Drive

    Hi - Some large scale 3D printers do this. But for a router I think it would increase the wobble factor. The gantry is on two rails and as it moves one side leads the other then the other side catches up. This occurs no matter the drive system. The elastic properties of the system dictate this. It's sort of a slip/stick mechanism. So you will have horizontal and vertical stick/slip occurring exaggerating the wobbles of the structure. I think the cons win... Ericks keep an eye on Maximus it will be real soon...Peter

  10. #10
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    Re: Pros and Cons of Using Dual Z Axis Drive

    Quote Originally Posted by ger21 View Post
    Oh, I thought you meant dual spindle, but you're talking about a gantry that moves up and down.

    Not sure any benefits would outweigh the cons. Much more weight to move up and down, and more money. And the only benefit is more gantry clearance?
    Less Spindle overhang and simpler Spindle mount as well , but I see what you mean.
    The complexity and cost do not justify the possible gains.

    It was just a thought.....lol

  11. #11
    Community Moderator ger21's Avatar
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    Re: Pros and Cons of Using Dual Z Axis Drive

    Careful design can also minimize spindle overhang.

    And your just shifting the Z axis ballscrew somewhere else, and doubling it. Make one part simpler, and two parts more complex.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  12. #12
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    Re: Pros and Cons of Using Dual Z Axis Drive

    Quote Originally Posted by ger21 View Post
    And your just shifting the Z axis ballscrew somewhere else, and doubling it. Make one part simpler, and two parts more complex.
    Yes, there is that.....

    Its a complex issue....

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