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  1. #1
    Join Date
    Nov 2009
    Posts
    4415

    X & A, possibly Z simultaneously?

    I have a small mill (A2ZCNC) with a Sherline rotary table vertically mounted so axis is parallel with X or horizontal (now that makes me unsure of what this axis is correctly referred to). Anyway tonight I was playing with some manually written G code and lowering the z and then moving the X back and forth, retract Z, rotate the A 60 degrees (or whatever that axis is called, I do call it A in my code) and basically repeat. It gives me a wrench flat and or flat sides down a otherwise round bar.
    That got me starting to think about how a ballscrew is made. I see it as
    Drop Z to first cut depth at starting point of X.
    Engage A and X at the same time (this is where my question lies). If I wanted A to rotate 720 degrees over the next 2" of X travel. One of the feedrates are going to override the other, right? Purely a hypothetical measurement not a real ballscrew. It really gives me a little more possibility with a wee little Sherline. Almost like a lathe with a milling head.
    I really think it would allow for some interesting twists in bar stock with out using the lathe.
    The other cool thing was that I could perform quite a few more functions without ever taking the part out. Similar to Simpson36's(?) machine making hose barbs.
    So how would I write that? ( 1 full rotation of A while X is traveling 1" and Z is fixed)
    Anyway any tips would be great.

  2. #2
    Join Date
    Feb 2006
    Posts
    1792
    Simultaneous control is possible if you have a 4-axis control.
    You use G01 only, with all four axis distances/angle.
    Feedrate of rotary axis ("A" is parallel to X, "B" parallel to Y and "C" parallel to Z. So, you have A-axis on your machine) is in deg/min, if commanded separately.
    If you use a linear axis as well as a rotary axis in G01 (as in your case), the commanded feedrate would be along the tangential direction of tool movement, i.e., along the spiral toolpath.
    This way you can generate a uniform pitch. If you need a complex contour, defined by lines/arcs, on the circumference, you need to have cylindrical interpolation available on your machine.

  3. #3
    Join Date
    Nov 2009
    Posts
    4415
    sinha, Thanks for the response. I do have 4 axis available. Maybe I am understanding you on how to use G01. I was under the impression that "A's" feedrate was overriden by "X's" and it appears it is. So can I write it like this?
    G01 Z0 F1 (clear of workpiece)
    G01 X0 F6 (starting point of X)
    G01 A0 F360 (starting point of A)
    G01 Z-.0125 A720 X2.25 F6 (would this plunge the Z in .0125, rotate 2 revolutions while starting at X0 and traveling to X2.25? Would it cut a spiral along the X axis with 2 revolutions over 2.25"?)

  4. #4
    Join Date
    Feb 2006
    Posts
    1792
    Simultaneous movement of all axes takes place so as to reach the programmed end point of each axis at the same time.
    So, it will cut a spiral, proceeding in Z-direction also, as X increases.

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