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Atypical Homing Setup

Discussion in 'CNC Mills/Routers' started by Mel Ristau, Dec 18, 2014.

  1. Mel Ristau

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    image.jpg
    The attached drawing shows that my switches are mounted on the gantry / not the rails. In brief, I'm wanting home to be at left back instead of left front. Can someone help me with Axis Settings and tinyG board (v8) terminal connections for my atypical homing setup? Am I creating a future workflow issue by doing this? thanks!
     
  2. Hytech2k

    Hytech2k Master
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    I can't help you with the tinyG board, but "typically" the 0,0 origin is bottom left. Now with that being said, workflow depends on how your setup. For a time I homed to the lower left but for all my work I set the work piece origin to the center just because I used a jig for multiple sized signs. Now I use a little thing called the Makers Guide to zero of the lower left corner every time. As long as you set the work piece origin point in your software I don't think it matters, in fact when I setup a new job in Aspire one of the first things you choose is what corner or center to set 0,0 too. Just my 2 cents...
     
  3. Mel Ristau

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    Thanks Hytech2k!
     
  4. Mel Ristau

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    So here's a working solution:
    image.jpg
    But I still don't understand why it works.
     
  5. Hytech2k

    Hytech2k Master
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    That really sounds like a software setup issue. For instance I run Mach 3 and I have to set the settings to homing in the negative direction for the X and Y and the positive for the Z. If I didn't it would move towards the + end of the machine till it hit a limit switch then zero out.

    Just a thought but you might try reposting this in the "Controller Boards" forum, seems like a few fellas there are running the tinyG's. Might get a bit more help there...
     
  6. Joe Santarsiero

    Joe Santarsiero OB addict
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  7. Mel Ristau

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    "What kind of switches?"
    Micro switches from Inventables wired NC.

    "Are you using the Github wiki?"
    Yes that's my primary guide.... Have about decided to just set homing up for typical homing at front/left.
    (Front/left makes sense if building a basic Shapeoko2. My machine has a max XY travel of 1100mm and most convenient for home to be rear/left.)
    The atypical setup in the attached drawing works but I don't understand why. (Seems like the Xmin switch should connect to the Xmin board position.
    Also, I don't understand if I'm creating future workflow issues by homing to rear/left.
    Think I will just abandon the rear/left objective and setup for typical front/left... Until I have more CNC experience.

    image.jpg
     
    #7 Mel Ristau, Dec 20, 2014
    Last edited: Dec 20, 2014
  8. David the swarfer

    David the swarfer OpenBuilds Team
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    you should not do this! (make the min and max ends reversed)
    the CNC standard is the X increases to the right, and Y increases going away from you, ie o,o is front left.
    just about all CNC software assumes this and cannot be changed. this means your parts may be cut flipped along a diagonal.

    generally is does not matter where you put the home switches along the axes since you can put an offset in the controller software that sets the real 0 position. if TinyG cannot do this then it should be fixed (-:
    ah yes, the 'zero backoff' setting for each axis is what you want.
     
  9. Mel Ristau

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    Thanks David - just the kind of advice I'm looking for.
     
  10. Serge E.

    Serge E. Master
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    An easy way to remember is to hold your left hand before you, thumb pointing up (Z+), index finger pointing away from you (Y+) and middle finger pointing right (x+). Where all three finger 'meet', that's your origin (0,0,0). That is the conventional setup.

    Place that origin wherever you want, keeping the relationship the same, and your CAD, CAM and machine should move correctly... In fact, you could wire your machine so what is normally the X becomes your Y and vice versa and you 'get' what you are looking for : the origin "becomes" the "rear left corner". the Y+ goes right, X+ goes towards you and Z+ remains going up. Easy, eh ? Just rotate your left hand clockwise 90 degrees and you'll get the 'picture'. ;)

    If you are a contortionist you can have your machine wired just about any which way as long as the relationship stays 'left-handed'. :cool:

    Have fun.
     
  11. Joe Santarsiero

    Joe Santarsiero OB addict
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    or you could just rotate your machine and swap axis to a long X and short Y and use it like the rest of the professional milling world does! Just sayin.

    long travel is X... short is Y. x0,y0 is bottom left. I don't know where the routing world got this from :)
     
  12. Serge E.

    Serge E. Master
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    Hey, that sounds like myOX with a 1500mm X and a 750mm Y, with the origin at bottom left. Not the largest around, I'll admit, but it fits the 'milling world' model. :oops: A few were asking why I went that way ... I just figured it would allow me to work on wide and long doors, sliding it through. Must of really been an influence from my dad being a machinist / tool & die maker? I did pay attention, as a kid at least, when he showed me those big milling machines ...
     
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  13. Joe Santarsiero

    Joe Santarsiero OB addict
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    With extensive machining experience myself, a longer x just feels natural. Especially, from a programming perspective. When one with a router considers making a long sign with a long Y...it's being machined rotated. Not knockin the community...just saying it doesn't feel natural or intuitive to me :]
     

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