• Time
  • Show
Clear All
new posts

  • Looping

    Hi folks,
    New to looping and having a problem. What I have is 4 parts in a row going left to right. I first tried to use my original alignment and program for this part, which consisted of a manual Iterative Alignment and a DCC Iterative Alignment(CAD), followed by an alignment per the print. It didn't work quite well because the part is rather small and the leveling and translating to the part itself skewed the measurement of the 3 other parts so much so that by the 4th part it would not touch the part.

    So, I then made an alignment to the fixture I have and then translated to get back to the actual part. At this point I did a CAD=PART. I then went on to do the print alignment(I'll call it ABC_ALIGN). I inserted the LOOP command here. I then recalled my ABC_ALIGN alignment. I measured 1 point and reported out the "T" deviation". At each successive loop of the program I am getting a larger and larger deviation, which indicates to me something is not right.

    My question(s) for the user group is this...
    1. Does it sound like I did this correctly?

    2. Is it wrong to put an alignment recall command inside of a of a LOOP command?(HELP file indicates that I shouldn't do this if the features used for the alignment are not within the LOOP).

    3.Does the insertion of a LOOP command into a part program have any of the ramifications like when inserting a CAD=PART into a program? It seems like the program gets funky when I have inserted and/or removed the LOOP command from the program.

    4.Any hints/tips/comments/questions?

    James Mannes

  • #2
    I've always been partial to using external alignments to offset your loop. This has two benifits.

    First you dont need to rely on the fixture having exact offsets, or the program offsetting along the part axis like you described.

    Second, you dont need to worry about PC-DMIS updating THEO values when executing the LOOP command (this is probably what you described being similer to CAD = PART which also updates Theo values). This can cause the "funky" behavior you described if you cancel execution at the wrong time, or try and step into the program.

    $$ NO,******************ALIGNMENT LOOP*********************
    V1         =LOOP/START, ID = NO, NUMBER = 4, START = 1, SKIP = ,
                   OFFSET: XAXIS = 0, YAXIS = 0, ZAXIS = 0, ANGLE = 0
    Just create a loop with no offset, and then use the loop variable to recall each stations alignment. Just make sure you uncheck the "Reset Global Variables" box in general setup options.


    • #3
      bump up to top

      James Mannes


      Related Topics


      • IDR_jt
        Alignment in a loop
        by IDR_jt
        We are working with our loop to measure 4 parts with offsets. We must to align each part separately in the fixture but we don’t know how to do that....
        09-18-2012, 12:23 PM
      • JBELL
        Another Loop Question
        by JBELL
        I have searched with no luck for an answer. I am very new to looping and have some questions. Right now, I am doing a Man align then loop commands then...
        11-04-2015, 02:58 PM
      • arock
        by arock
        Trying to figure out this looping.... I got as far as taking the first feature of the alignment on the second part! Then it went way over in space and...
        06-14-2018, 08:44 AM
      • louisd
        Loopity loopy loops
        by louisd
        I'm trying to optimize path of a routine that measures anywhere from 1 to 4 parts set on a fixture (variable QTY.INPUT). Fixture positions are spaced...
        10-10-2018, 04:49 PM
      • brianparker
        Alignment fail in loop?
        by brianparker
        Can anyone shed light on this? Have a manual (marked off) and DCC alignment in my program, runs one part great. When it moves to my second part, I believe...
        01-27-2020, 02:44 PM