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  1. #1
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    Question touch probe rotation cycle

    dear all,

    i have the following question

    1- if i have an inclined (not straight) rectangular block on machine bed, how to get its center points (in X and Y) with the inclination angle ?? i mean how to use axes rotation cycle to measure this inclined block via touch probe??

    the machine control is Fanuc 0imc
    the touch probe used is : Blum TC50 ( a German brand like Renishaw )

    the macro used in measuring cycle in attachment (the main macro is 9700 and all sub macros from 9701 to 9709)
    Attached Files Attached Files

  2. #2
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    On a 3-axis machine, it may not be possible.

    State your problem more clearly, preferably with a drawing, and write what exactly you want to measure.

    I am not able to open the file attached by you.

  3. #3
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    thanks Sinha for your reply,

    the problem in details as follow:

    i want to measure the center point of a rectangular die on machine center bed.

    we usually use a dial indicator to make this die 100% horizontally .

    we need to use this Blum to measure the center point of this die without using indicator (to save setup time).

    the machine move as photo number 1 and this cause the center to be wrong.

    we need to make the machine path like photo number 2.

    i hope it's clear now

    for the file in previous attach it was for measuring cycle (macro programs ).

    i will attach it again.
    Attached Thumbnails Attached Thumbnails 1.jpg   2.jpg  
    Attached Files Attached Files

  4. #4
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    Measuring center points by X and Y (look at brown lines) will give you the figure center. After that you should measure also the rotation angle
    Attached Thumbnails Attached Thumbnails PIC2.jpg  

  5. #5
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    I have derived formulae for a similar problem (finding the angle of an edge, and the coordinates of the lower left corner of a rotated rectangle). If you are interested, let me know. I would post these here.

  6. #6
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    yes please we need this formula badly

  7. #7
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    Formulae attached.

    I located the lower left corner, and the angle of the lower edge with X-axis. You need the center. So, more derivation is needed, after touching the workpiece from all sides.
    Attached Files Attached Files

  8. #8
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    Dear Sinha,

    the document you attached is helpful, but what if i need the coordinates of program zero point to be in the center of the workpiece (i mean not in the lower corner) ??

    is it possible, if yes how can i do this ??

  9. #9
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    Yes. It is possible. This is all coordinate geometry. You need to know how to write the equation of a line, and how to find the intersection point of two lines. I have not done this, but it can be done. If you are not comfortable with such calculations, but need the formulae desperately, let me know. I will do it for you.

  10. #10
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    yes Sinha, i need the formula and no need for the equation.

    i just want the Probe to go to the correct center.

    my problem is how to make Probe measure the correct center point of an inclined workpiece, because as you know, Probe (which mounted in the spindle) moves in horizontal and vertical movements (not inclined movement), once i get the center of rotation i will activate G68 and every thing will be great

  11. #11
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    OK. Give me a day or two. It is a bit complicated.

  12. #12
    I had a go at this I don't have any way of testing it though.


    %
    ;O0001
    ;(GET 3 Z AND X POSITIONS)
    ;(1ST PROBE)
    ;(Z1)
    #1
    ;(X1)
    #2
    ;(2ND PROBE)
    ;(Z2)
    #3
    ;(X2)
    #4
    ;(3RD PROBE)
    ;(Z3)
    #5
    ;(X3)
    #6
    ;(GET ANGLE)
    #100=ATAN[[#3-#1]/[#4-#2]]
    ;(TEST IF Z3 IS MORE OR LESS THAN Z1 AND OUTPUT VAR)
    IF [#5>#1] THEN #69=[#6-#2+[[#5-#1]TAN#100]]
    IF [#5<#1] THEN #69=[#6-#2-[[#1-#5]TAN#100]]
    ;(OUTPUT X POSITION)
    #5221=#2+[#69[COS#100]]
    ;(OUTPUT Z POSITION)
    #5223=#1+[[#5221-#1]TAN#69]
    M99
    %
    Attached Files Attached Files
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    ************************************************** *********
    *__________If you feel inclined to pay for the support you receive__________*
    *_______Please give to charity https://www.oxfam.org.au/get-involved/_______*
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  13. #13
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    First you have to use the method I suggested in a previous post, to find out the angle of the lower edge with X-axis, and the coordinates of the lower left corner.

    Once the slope (m) is known, you can move the probe, parallel to edges:
    #100 = <m>;
    G91 G00/G01/G31 X100 Y[100*#100] F_ ;(movement parallel to "horizontal" edge, towards right)
    or
    G91 G00/G01/G31 X-100 Y-[100*#100] F_ ;(movement parallel to "horizontal" edge, towards left)
    or
    G91 G00/G01/G31 Y100 X-[100*#100] F_ ;(movement parallel to "vertical" edge, upwards)
    or
    G91 G00/G01/G31 Y-100 X[100*#100] F_ ;(movement parallel to "vertical" edge, downwards)

    By moving the probe parallel to edges, you can measure the length and breadth of the workpiece, after touching it from all the four sides, along the same orthogonal lines. For example,
    width = square root of (delta X square + delta Y square) - dia of probe
    where delta X and delta Y are differences in coordinates of probe center, at the two touch points.

    Now workpiece center can be calculated in the following manner:
    #101 = <length>/2;(calculating half length)
    #102 = <breadth>/2;(calculating half breadth)
    X coordinate = X coordinate of lower left corner + #101*COS[<angle>] - #102*SIN[<angle>];
    Y coordinate = Y coordinate of lower left corner + #101*SIN[<angle>] + #102*COS[<angle>];

    With such a macro, no matter how you clamp the workpiece on the table, you would be able to machine correctly.

  14. #14
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    Thanks for your great help Sinha,

    but shall i use a Macro to calculate slope "m" value ? if yes, i do not have such this macro... so can you help me to develop it ??

    then, shall i type the following program in the MDI ?? or what ??

    #100 = <m>;
    G91 G00/G01/G31 X100 Y[100*#100] F_ ;(movement parallel to "horizontal" edge, towards right)
    or
    G91 G00/G01/G31 X-100 Y-[100*#100] F_ ;(movement parallel to "horizontal" edge, towards left)
    or
    G91 G00/G01/G31 Y100 X-[100*#100] F_ ;(movement parallel to "vertical" edge, upwards)
    or
    G91 G00/G01/G31 Y-100 X[100*#100] F_ ;(movement parallel to "vertical" edge, downwards)

    #101 = <length>/2;(calculating half length)
    #102 = <breadth>/2;(calculating half breadth)
    X coordinate = X coordinate of lower left corner + #101*COS[<angle>] - #102*SIN[<angle>];
    Y coordinate = Y coordinate of lower left corner + #101*SIN[<angle>] + #102*COS[<angle>];

  15. #15
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    A single macro would do everything. Formula for m is also given in a previous post. I have given the required mathematical basis for such a macro.

    You first have to practice with a simple probing program, such as finding depth of a pocket. Next, try to write a macro for finding center of a rectangular pocket, the edges of which are parallel to X/Y axes. Then, modify it to place the workpiece zero point (which is the origin of the chosen workpiece coordinate system such as G54). When you are able to do these things successfully, you can proceed to the present problem. Make a small and easily achievable target first. This would give you enough confidence to proceed further. Do not worry about the time factor. Nobody learns in a day. It takes months, maybe years, to develop expertise. Someday, you will definitely stand on your own and guide others. You only have to keep trying steadily.

  16. #16
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    Re: touch probe rotation cycle

    Would it be the same with the center of 2 holes 45mm apart in Y axis? The center between the 2 hole is center of rotation rotation. Holes are 5.16mm Center is Y 22.5 from each hole.



    The Hole Spacing
    X0.00 Y+22.5
    X0.00 Y -22.5

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