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Upside-down Alignment

button.monkey
Hey guys. I'm trying to do an iterative alignment on a fixture but I'm hitting a speed bump and I'm not sure whats causing it. The points for the manual alignment are identical to the automatic alignment and share all the same properties. The manual alignment shows the vector correctly but the probe is upside down. The automatic one shows the vector correctly and the probe in the correct orientation. I've posted the code below as well as attached a picture of the "upside down probe". Does anyone see where the issue lies? When I run it, I go through the manual alignment and then when it attempts to measure the Master tooling ball on its own, it tries to go to the centre of the tooling ball and reads an unexpected probe hit. Running PC-DMIS 3.7 MR3

upside-down probe 

STARTUP    =ALIGNMENT/START,RECALL:, LIST= YES
            ALIGNMENT/END
            MODE/MANUAL
            LOADPROBE/2X20_E30
            TIP/T1A0B0, SHANKIJK=0, 0, 1, ANGLE=0
            FORMAT/TEXT,OPTIONS, ,HEADINGS,SYMBOLS, ;NOM,TOL,MEAS,DEV,OUTTOL, , 
            ASSIGN/INPUT_CUSTOMER_P = "xxxxx"
            ASSIGN/JOB_INPUT_P = "xxxx"
            ASSIGN/PART_NAME_INPUT_P = "xxxxxx"
            ASSIGN/PART_NUM_INPUT_P = "xxxxx"
            ASSIGN/TM_INPUT = "xxx"
            ASSIGN/TZ_INPUT = ""
            MOVESPEED/ 75
            TOUCHSPEED/ 1
            PREHIT/ 4
            RETRACT/ 2
MASTER_M   =AUTO/SPHERE,SHOWALLPARAMS = YES,SHOWHITS = NO
            THEO/2299.95,-700.08,1262.45,0,0,-1,12.7
            ACTL/372.654,161.77,-483.981,0,0,-1,12.689
            TARG/2299.95,-700.08,1262.45,0,0,-1
            THEO_THICKNESS = 0,RECT,OUT,$
            AUTO MOVE = BOTH,DISTANCE = 5,$
            NUMHITS = 5,NUMROWS = 2,INIT = 0,PERM = 0,SPACER = 1,$
            START ANGLE 1 = 360,END ANGLE 1 = 0,$
            START ANGLE 2 = 0,END ANGLE 2 = 90,$
            ANGLE VEC = 0,0,1
LINE_M     =AUTO/SPHERE,SHOWALLPARAMS = YES,SHOWHITS = NO
            THEO/2299.95,-175.076,1262.4,0,0,-1,12.7
            ACTL/370.56,686.758,-483.94,0,0,-1,12.69
            TARG/2299.95,-175.076,1262.4,0,0,-1
            THEO_THICKNESS = 0,RECT,OUT,$
            AUTO MOVE = BOTH,DISTANCE = 5,$
            NUMHITS = 5,NUMROWS = 2,INIT = 0,PERM = 0,SPACER = 2,$
            START ANGLE 1 = 360,END ANGLE 1 = 0,$
            START ANGLE 2 = 0,END ANGLE 2 = 90,$
            ANGLE VEC = 0,0,1
PLANE_M    =AUTO/SPHERE,SHOWALLPARAMS = YES,SHOWHITS = NO
            THEO/2549.948,-700.101,1262.4,0,0,-1,12.7
            ACTL/122.679,160.773,-483.972,0,0,-1,12.714
            TARG/2549.948,-700.101,1262.4,0,0,-1
            THEO_THICKNESS = 0,RECT,OUT,$
            AUTO MOVE = BOTH,DISTANCE = 5,$
            NUMHITS = 5,NUMROWS = 2,INIT = 0,PERM = 0,SPACER = 2,$
            START ANGLE 1 = 360,END ANGLE 1 = 0,$
            START ANGLE 2 = 0,END ANGLE 2 = 90,$
            ANGLE VEC = 0,0,1
A0         =ALIGNMENT/START,RECALL:STARTUP, LIST= YES
            ALIGNMENT/ITERATE
              PNT TARGET RAD = 0.5, START LABEL = , FIXTURE TOL = 0.12, ERROR LABEL = 
              MEAS ALL FEAT = NO ,MAX ITERATIONS = 99 ,LEVEL AXIS=ZAXIS ,ROTATE AXIS=XAXIS ,ORIGIN AXIS=YAXIS
            LEVEL = MASTER_M,LINE_M,PLANE_M,,
            ROTATE = MASTER_M,LINE_M,,
            ORIGIN = MASTER_M,,
            ALIGNMENT/END
            MODE/DCC
            MOVE/POINT,NORMAL,2371.693,-704.155,1074.34
MASTER     =AUTO/SPHERE,SHOWALLPARAMS = YES,SHOWHITS = NO
            THEO/2299.95,-700.08,1262.45,0,0,-1,12.7
            ACTL/2299.95,-700.08,1262.45,0,0,-1,12.7
            TARG/2299.95,-700.08,1262.45,0,0,-1
            THEO_THICKNESS = 0,RECT,OUT,$
            AUTO MOVE = BOTH,DISTANCE = 5,$
            NUMHITS = 9,NUMROWS = 2,INIT = 0,PERM = 0,SPACER = 1,$
            START ANGLE 1 = 0,END ANGLE 1 = 360,$
            START ANGLE 2 = 0,END ANGLE 2 = 90,$
            ANGLE VEC = 0,0,1
            MOVE/POINT,NORMAL,2300.86,-688.662,999.186
            MOVE/POINT,NORMAL,2203.265,-689.038,999.197
            MOVE/POINT,NORMAL,2201.072,-140.423,999.19
            MOVE/POINT,NORMAL,2345.682,-173.786,1215.66
LINE       =AUTO/SPHERE,SHOWALLPARAMS = YES,SHOWHITS = NO
            THEO/2299.95,-175.076,1262.4,0,0,-1,12.7
            ACTL/2299.918,-175.105,1262.406,-0.0000344,0.0000062,-1,12.7
            TARG/2299.95,-175.076,1262.4,0,0,-1
            THEO_THICKNESS = 0,RECT,OUT,$
            AUTO MOVE = BOTH,DISTANCE = 5,$
            NUMHITS = 9,NUMROWS = 2,INIT = 0,PERM = 0,SPACER = 2,$
            START ANGLE 1 = 360,END ANGLE 1 = 0,$
            START ANGLE 2 = 0,END ANGLE 2 = 90,$
            ANGLE VEC = 0,0,1
            MOVE/POINT,NORMAL,2349.049,-152.543,929.8
            MOVE/POINT,NORMAL,2453.275,-206.54,929.787
            MOVE/POINT,NORMAL,2559.6,-653.308,929.781
            MOVE/POINT,NORMAL,2580.739,-695.373,1215.982
            MOVE/POINT,NORMAL,2567.678,-716.314,1262.361
PLANE      =AUTO/SPHERE,SHOWALLPARAMS = YES,SHOWHITS = NO
            THEO/2549.948,-700.101,1262.4,0,0,-1,12.7
            ACTL/2549.915,-700.131,1262.394,-0.0000344,0.0000062,-1,12.7
            TARG/2549.948,-700.101,1262.4,0,0,-1
            THEO_THICKNESS = 0,RECT,OUT,$
            AUTO MOVE = BOTH,DISTANCE = 5,$
            NUMHITS = 9,NUMROWS = 2,INIT = 0,PERM = 0,SPACER = 2,$
            START ANGLE 1 = 360,END ANGLE 1 = 0,$
            START ANGLE 2 = 0,END ANGLE 2 = 90,$
            ANGLE VEC = 0,0,1
            MOVE/POINT,NORMAL,2540.867,-687.7,1055.002
A1         =ALIGNMENT/START,RECALL:STARTUP, LIST= YES
            ALIGNMENT/ITERATE
              PNT TARGET RAD = 0.5, START LABEL = , FIXTURE TOL = 0.12, ERROR LABEL = 
              MEAS ALL FEAT = NO ,MAX ITERATIONS = 99 ,LEVEL AXIS=ZAXIS ,ROTATE AXIS=XAXIS ,ORIGIN AXIS=YAXIS
            LEVEL = MASTER,LINE,PLANE,,
            ROTATE = MASTER,LINE,,
            ORIGIN = MASTER,,
            ALIGNMENT/END
  • The first alignment is a rough alignment on the tooling balls. The second is a more accurate one done by the machine. I'm not aligning to the part in this case because the fixture has pins protruding through the 4way hole and 2 way slot which are covered by the clamps. So basically I have no datum features to work with. The fixture was poorly designed (it has a mating check feature that collides with a tab and if the tab wasn't there it would hit a side wall lol...) Anyways the customer knows about these issues and decided to go ahead and use the fixture anyways so I'm working with what I've got. I've done a handful of alignments this way and it's never been a problem.

    Retract and prehit are not the issue; I tried playing with those yesterday with no luck.

    Thanks for the input though

    You don't need to align to the part. Leave the part off and align to the fixture. Then put the part on after.

    did you do a setup option of part/machine. Part setup, Cad +X equals machine axis and so forth.

    Always us measure all always but make sure your prehit and retract are high enough to clear part.

    Why are you doing the second alignment?

    After you first alignment you should be checking the nets and the 2 and four way locators and then maybe use them to fine tune alignment    .'

    So get rid of your second alignment and see what happens./

    I do agree with the bolded part above. The manual alignment on the tooling balls with Measure All Once checked, and then move on to the locators from the fixture. But, it's not very helpful if you can't get the machine to get through the single iterative of the manual alignment.

    I disagree with worrying about changing the machine axis though. Probably just a personal preference, but after the manual alignment, everything syncs up so it is just extra work.

    i'll ask the simple question first... how can you possibly hit a point in space in Z- with a probe angle of AOBO?

    second, why are the theos so far out of wack with the actuals on the manual features?

    sounds like a workplane issue to me

    For tooling balls on the manual alignment, this is expected. It is normal behavior.

    presuming workplane = Z+
    with the fixture laying on the granite
    looking "down" at the fixture
    are the tooling balls facing you?
    if so they should have a K vector of 1, not -1

    When working with fixtures in car body and iterative alignments this is 100% false.
  • The workplane is Z-. I originally had it in the code but then tried removing it to see if that would have an effect, which it didn't. I think the probe looking upside down was just because my cursor wasn't far enough down the script to take the alignment into account. The real issue seems to be that the probe wants to cut the tooling ball in half.

    When you have the edit window open, what does the hit path of the sphere look like? Does it look right?

  • When working with fixtures in car body and iterative alignments this is 100% false.

    I stand corrected. I don't have the luxury of CAD models.
  • I've run into this before and these are all good suggestions. I would try changing the auto move for the sphere to NO instead of BOTH. I've noticed that in DCC it can cause the probe to try to go to the center of the sphere before taking hits.
  • The hit path looks ok although, when you open up the feature panel, the animation it shows goes through the probe to touch on a plane that divides the tooling ball in half.
  • Hey guys. I'm trying to do an iterative alignment on a fixture but I'm hitting a speed bump and I'm not sure whats causing it. The points for the manual alignment are identical to the automatic alignment and share all the same properties. The manual alignment shows the vector correctly but the probe is upside down. The automatic one shows the vector correctly and the probe in the correct orientation. I've posted the code below as well as attached a picture of the "upside down probe". Does anyone see where the issue lies? When I run it, I go through the manual alignment and then when it attempts to measure the Master tooling ball on its own, it tries to go to the centre of the tooling ball and reads an unexpected probe hit. Running PC-DMIS 3.7 MR3

    upside-down probe



    I don't see anything wrong with your alignment. Based on the nominal and actual data it appears that you have oriented the fixture along the same axis of the machine. Also, after the alignment you check the spheres in DCC which only show minimal error.

    Maybe you imported the wrong cad file for this fixture? A left hand cad file for a right hand fixture perhaps? You are only looking at the probe relative to the cad model.

    Note: The sphere IJK vectors should not be <0,0,-1> but <0,0,1>. This won't cause a problem with your alignment but might cause issues when measuring depending on the options you use. PC-DMIS will think the top of the sphere is at the bottom.
  • So I changed the automove to NO and that fixed the issue. Thanks JM for the tip! I'll remember that for next time.

    Ron, this is definitely the correct CAD model. The workplane is Z- so in this case the vector is 0,0,-1 for the tooling balls. If I make a random point on a flat surface of the part the auto vector is 0,0,-1.

    I'd like to say thanks to everyone for the replies and the input. It was all great advice for troubleshooting that I'll keep in mind for the future. I'm still relatively new to this so I appreciate the help. All the replies were positive which felt great. I've read a few threads that weren't nearly as polite

    Thanks again everyone,
    Button.Monkey
  • Good catch!
    If the spheres are 12.7 mm diameter they will definitely need an "automove" bigger than 5.
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