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  1. #1

    Default Z axis question. Please help

    Hi there,
    I'm looking for help assessing the usability of a Parker linear actuator I bought for use as my z axis.
    Im building a mechmate wood router. I've completed the base which I've made extra heavy (1700 lb) in hopes of increasing speed and accuracy. 97% of the time I'll be cutting wood.
    I purchased a Parker actuator, somewhat impulsively, at an auction near my house. My thought was this would potentially save me time and money from having to fabricate my own however I'm not sure if it is robust enough for what I'm seeking to do.
    It has 12" travel. I've attached the spec sheet on it.
    Any help regarding the usability of this would be greatly appreciated.

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    Last edited by Panovak; 01-31-2020 at 09:44 PM.


  2. #2
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    Default Re: Z axis question. Please help

    It will work but the question is will it give the results you want. It looks like the round rails are fully supported if so that is a good thing! If not it would be best to use this on a very light duty machine. If you look at the specs the slide just barely passes for what I would consider to be acceptable design forces. I’m on my laptop home at the moment and have already forgotten the specs but I think it was 60 pounds side loading. I’d call that a light to medium duty slide for a router.

    People like to knock round rails and there are some megood reasons to do so but at the right price they are far better than many of the cheaper or DIY solutions for linear motion. The slide will work but as I said it depends upon what your expectations are. If it doesn’t meet expectations it will be good enough to machine a replacement out of aluminum. So I really don’t see a reason not to use the slide. If you pay attention to the gantry (y axis) saddle rigid mounting should be easy. It you have concerns make the saddle large enough to accept a larger Z axis in the future. You didn’t mention the going price but I imagine that the leadscrew itself is worth what you paid.



  3. #3

    Default Re: Z axis question. Please help

    Thanks for your input. Indeed it is fully supported. It's linear rails supports are machined from same piece as back plate. It's rated at 168lbs side loaded. I paid $150 for it so I'm not committed to using it. I just don't want the z axis to be the weak part of my build.
    Would it be worth my effort to machine the back plate flat and mount profile rails? I have access to machining tools.
    Thanks

    Last edited by Panovak; 02-01-2020 at 02:24 PM.


  4. #4

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    I attached a couple images of the actuator with side plate and carriage removed.

    Attached Thumbnails Attached Thumbnails Z axis question. Please help-img_20200201_131620037-jpg   Z axis question. Please help-img_20200201_131639130-jpg  


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    Default Re: Z axis question. Please help

    It will probably work as is. If you're dissatisfied with its performance, you could always replace the rails with better ones, but it will probably be just fine. Are you trying to reuse the original motor, or fitting your own? Be sure to use a flexible coupler of some sort if you're putting a new motor on it; a little misalignment will otherwise snap either the motor shaft or the screw.

    Andrew Werby
    https://computersculpture.com/


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    Community Moderator ger21's Avatar
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    Default Re: Z axis question. Please help

    If it's a standard Mechmate using V Rollers and gravity, it'll probably be fine.

    Building a heavy frame with a mechmate doesn't really help much, unless you build it with linear rails instead of V Rollers.

    Gerry

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  7. #7

    Default Re: Z axis question. Please help

    Thanks for the replies. I will be using linear guides and Rack and pinion on the rest of the machine.



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    Community Moderator ger21's Avatar
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    Default Re: Z axis question. Please help

    Then you may find this to be the weak point. Round shafts are no where near as rigid as linear bearings.

    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)


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    Default Re: Z axis question. Please help

    I would go for it as is. As noted ball bushings are not as rigid as some other choices but on the other hand they are worlds better than some DIY solutions I've seen. It sounds like the slide is built to get the best possible results from ball bushings.

    In the end it still comes down to your expectations. Realistically you got the slide at bargain pricing so that is a good thing. the only other concern is how you will use the machine, I wouldn't call it a solution for heavy machining but that doesn't make it a bad choice. You stated that the machine is being built heavy which is great but simply being heavy will not solve all problems, you need to focus on rigidity and that has to be from the bottom up.

    If you do decide that it isn't the right choice, I would sell the assembly and use the machining facilities you have access to, too build a Z that meets all of your needs. Having access to machine tools is a massive advantage that a lot of DIY types simply don't have. It can make a huge difference in what you can create.



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Z axis question. Please help

Z axis question. Please help

Z axis question. Please help