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    Default Probing multiple points on surface to find high and low

    I have a question that maybe you fellow programmers could shed some light on. What I am working with is a Mitsubishi MVR40 gantry mill with a Fanuc 31i controller. What we are planning on doing is to use the probe and touch off on 29 spots on a ring surface to check it for surface height. We will want to compare the points and find the highest point and also the lowest point to make sure it doesn't excede a set value of .125". I know how to program the probe for the 29 touch off points and then apply those values to 29 different variables. Is there a fairly easy way to compare the 29 points or is it going to take a "bunch" of code lines to do all the IF THEN compares? I may have to rethink this but we are pretty well locked into finding this info out on this many points. Thanks in advance.

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    Default Re: Probing multiple points on surface to find high and low

    I would think you could use a couple of variables (one for highest, one for lowest). Store the value of the 1st point in both then use a WHILE loop to compare the next point to each. If it's > than the "highest" variable, replace it, or if it's < the "lowest" variable, replace that.



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    Default Re: Probing multiple points on surface to find high and low

    Do you need to "remember" the location of the high and low points?
    Or just know the range?

    Control the process, not the product!
    Machining is more science than art, master the science and the artistry will be evident.


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    Default Re: Probing multiple points on surface to find high and low

    Hi,
    store every point to a variable, then
    at the end run 2 while's,
    1st to find the highest and
    2nd find the lowest value (and the point at the same time)



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    Default Re: Probing multiple points on surface to find high and low

    ProProcess,
    I do will need to "remember" the locations because of having to back spot face the locations within a range according to the print. The need to know the high to low range is to let the operator know if the part is going to be within range to mill a ring on the top surface and not go beyond the max allowed on the print. We are dealing with a large weldment and the plate surface will vary depending on how the shop welds the part up. I will need to bring myself up to speed on how to configure the 'while' arguments. Thanks for the responces.

    Kelly



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    Default Re: Probing multiple points on surface to find high and low

    Will you be doing work at all 29 locations?
    What happens if the range is too high? Part is rejected? Part needs realigned?

    It sounds like we do not have all the information to help you with what you really need.
    Maybe write out all the steps you want to perform in simple terms and we could provide you with a more complete direction.

    Control the process, not the product!
    Machining is more science than art, master the science and the artistry will be evident.


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    Default Re: Probing multiple points on surface to find high and low

    There will be work getting done at all 29 locations. This is going to be just one part of using a probe to find certain features on this part. On the area I have the questions about is in the screen shot. We are allowed a max of .125" material removal on the machined ring surface. Then a max .030" call out for a back spot face is also called out on the print. I figure on using the touch off points to aid in controlling the back spot depths we machine into the part. The front side is where I have had my questions on how to utilize the probe touch off points in figuring if the plate is for one warped to much. From the touch off points we will need to find the high spot and low spot to check the variance to make sure it doesn't excede the .125" range. And then figure the lowest spot, once the part is deemed good to machine, to setablish the Z0 point for the workshift. I have though about this and figure I could cut down on the number of points to do the compare to for the top surface but will need to use all the points for the back spot facing feature cutting. Using 11 points for the top surface compare should work out fine and give a good representation on the weldment. Thanks for the help everyone.
    Probing multiple points on surface to find high and low-top-ring-face-jpg



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    Default Re: Probing multiple points on surface to find high and low

    I would do it like this then...

    Save all your probed points in variables #101-#129 {points 1-29 i.e. #101 is point 1 and so on}.

    Run this Macro...

    Code:
    #1=101(initial count var)
    #130=##1(initalize highpoint)
    #131=##1(initialize lowpoint)
    #132=#0(clear result)
    
    WHILE[#1LE129]DO1
    G4
    IF[##1GT#130THEN#130=##1(save highpoint)
    IF[##1LT#131THEN#131=##1(save lowpoint)
    #1=[#1+1](iterate var)
    END1
    
    #132=[#130-#131](set range)<<<this should always yield a positive range result.
    (test result for alarm)
    IF[#132GT.125]THEN#3000=911(RANGE-EXCEEDS.125)

    I have not tested this, that will be up to you.
    I hope this helps.
    Let me know if you have questions.

    Last edited by ProProcess; 04-06-2015 at 12:38 PM. Reason: added comment
    Control the process, not the product!
    Machining is more science than art, master the science and the artistry will be evident.


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    Default Re: Probing multiple points on surface to find high and low

    Thanks to all,
    I think I have it figured out. This is what I have some up with. I will let you know down the road if it works out the way we want.

    Kelly


    (NOW TO COMPARE SURFACE HEIGHTS TO FIND HIGH TO LOW RANGE)
    (USING 29 POINTS)
    (AFTER THE COMPARE WE WILL USE THE LOWEST VALUE TO SET THE Z OFFSET)

    (NEED TO FIGURE THE HIGH SPOT OUT OF THE 29 POINTS)
    #10=1.(THIS IS TO COMPARE THE Z VALUES TO)
    (THIS WILL LOOP TO FIND THE HIGH AND LOW VALUES)
    WHILE[#10LE29]DO1
    IF[#10GT1]GOTO10
    #12=#861(HIGH VALUE COMPARE)
    #14=#861(LOW VALUE COMPARE)
    GOTO30
    N10(COMPARE LINES TO CHECK FOR HIGH OR LOW)
    IF[#[861+#10]GT#12]GOTO20
    IF[#[861+#10]LT#14]GOTO25
    GOTO30
    N20(NEXT LINE WILL SET THE NEW HIGH VALUE TO #12)
    #12=#[861+#10](SETS NEW HIGH POINT VALUE)
    GOTO30
    N25(NEXT LINE WILL SET NEW LOW VALUE TO #14)
    #14=#[861+#10](NEW LOW VALUE IS ESTABLISHED)
    N30(END OF COMPARE FOR POINT #861 + LAST #10 VALUE)
    #10=#10+1.(INCREMENT COUNTER)
    (THIS WILL KEEP COUNTING UP UNTIL THE 'WHILE' VALUE IS REACHED)
    END1(KEEPS LOOPING UNTIL ALL POINTS ARE COMPARED)

    (NOW TO COMPARE THE HIGH AND LOW SPOT)
    #15=0.110(**TOTAL VARIANCE ALLOWED BETWEEN HIGH AND LOW**)
    (PRINT CALLS .125" MAX DEPTH)
    (LEAVE SOME FOR FULL CLEAN UP ON MILLING)
    #890=[ABS[#12]]+[ABS[#14]](TOTAL DIFFERENCE BETWEEN HIGH AND LOW POINTS)
    IF#890LE#15GOTO50(CHECKING MAX DEVIATION)
    #3000=100(****TOP PLATE NOT FLAT ENOUGH****)
    (BETTER DECIDE WHAT TO DO WITH PART)
    (***LOOK AT VARIABLE #890 TO SEE TOTAL VARIANCE BETWEEN HIGH AND LOW***)

    N50(NOW TOP SET Z DATUM TO G55 WORKSHIFT)
    #5243=#5243+#14(TAKES THE LOW POINT AND ADDS INITIAL DATUM PLANE)
    (COULD BE POSITIVE OR NEGATIVE VALUE MOVE)
    (G55 WORKSHIFTS ARE NOW SET FOR TOP FEATURES)



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    Default Re: Probing multiple points on surface to find high and low

    You could write a bubble sort routine that would sort the Variables in ascending order and then get the difference between the smallest and largest value...



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Probing multiple points on surface to find high and low

Probing multiple points on surface to find high and low