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  1. #1

    Join Date
    Aug 2019
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    2

    An idea for a CNC.

    I have access to a rather large plasma table. I was thinking of using it to cut out a cnc from a single sheet of 1/2 hot rolled steel and use SBR20 linear rail kit from ebay. I already have a pretty nice spindle for my MPCNC that I'll be using.

    I put together a quick sketch of my idea what do y'all think? I'm worried that z movement will be roughly 23" and I'll loose 7" to the spindle mount. However this is just a quick idea I had any advice or input is welcome.

  2. #2
    Gold Member
    Join Date
    Apr 2004
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    5110

    Re: An idea for a CNC.

    Hot rolled steel isn't very flat to start with. Cutting a slab of it into pieces with a plasma cutter isn't going to help with that. But any surfaces you intend to mount rails to need to be extremely flat. Are you taking the rough assembly out for heat-treating and then having someone machine it flat? Or did you have some other plan that would make this work?
    Andrew Werby
    Website

  3. #3

    Join Date
    Aug 2019
    Posts
    2

    Re: An idea for a CNC.

    I didn't think of the surface finish on it, I guess I'll look into other materiel.

  4. #4
    Gold Member
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    Apr 2004
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    5110

    Re: An idea for a CNC.

    The surface finish isn't the main problem, it's the basic flatness of the material. If you put a straightedge on top of a piece of it, you'll see daylight in places where the metal dips down a little. That's enough to keep your rails from working correctly.
    Andrew Werby
    Website

  5. #5
    Community Moderator ger21's Avatar
    Join Date
    Mar 2003
    Posts
    35095

    Re: An idea for a CNC.

    Those round SBR20 are not a good choice, as they are not very rigid. Profile linear rails like THK or Hiwin are a much better choice.
    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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