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Hard to get points.

Tested
Some times it's a very small ledge at the bottom of a hole. Some times it's a rib on a boss.
When things get really tight and I have a multiple cavities where I know I'll have slight differences.
I use other features to allow for good hits.
Here I measure the Diameter, take the radius from that feature "CIR4.R.ACTL"
I'm using a Ø2mm probe tip so I subtract half the tip "1mm" plus enough so that I will miss the wall but yet stay very close to it "0.125mm" and assign that to FRM_CENT1
Then I take a point after which I edit that point by placing my new "FRM_CENT1" the first position of the "THEO" and the "TARG".
This allows for the cavities and/or part to part to very and the CMM to still make good touches.

CIR4 =FEAT/CONTACT/CIRCLE,CARTESIAN,IN,LEAST_SQR
THEO/<0,0,15.9172>,<0,0,1>,10.9924,361,361
ACTL/<0.0937,-0.067,15.9172>,<0,0,1>,10.9537,361,361
TARG/<0,0,15.9172>,<0,0,1>
ANGLE VEC=<1,0,0>
DIRECTION=CCW
SHOW ADVANCED MEASUREMENT OPTIONS=NO
SHOW_CONTACT_PARAMETERS=NO
ASSIGN/FRM_CENT1 = CIR4.R.ACTL-1.125
MOVE/POINT,NORMAL,<0.9132,-0.0326,13.613>
PNT_SPLINE_SIDA1=FEAT/CONTACT/VECTOR POINT,POLAR
THEO/< FRM_CENT1,-12.2152,15>,<0,0.9999939,0.0034907>
ACTL/<4.4646,-17.6739,14.9985>,<-0.0004155,0.9999938,0.0034907>
TARG/< FRM_CENT1,-12.2152,15>,<0,0.9999939,0.0034907>
SNAP=YES
SHOW ADVANCED MEASUREMENT OPTIONS=NO
SHOW_CONTACT_PARAMETERS=YES
AVOIDANCE MOVE=NO,DISTANCE=0
SHOWHITS=NO
  • I think I do about the same thing with an Edge point. I set both indent and depth to a minus value. Probe hits to find the edge then measures out the depth value to come down real close to the vertical surface. Adjust indent and depth for probe and vertical wall size. 

    PNT182     =AUTO/EDGE POINT,SHOWALLPARAMS = YES
            THEO/-2.9022,-2.3824,0,0,0,1
            ACTL/-2.9022,-2.3824,0,0,0,1
            TARG/-2.9022,-2.3824,0,0,0,1
            THEO_THICKNESS = 0,RECT,EDGE ACTL_THICKNESS = 0,ONERROR = NO,$
            AUTO MOVE = BOTH,DISTANCE = 0.2,RMEAS = None,None,None,MEASURE ORDER = SURFACE,$
            SURFACE NORMAL = 0,-1,0,$
            INIT = 1,PERM = 1,SPACER = 0.05,INDENT = -0.1,DEPTH = -0.05
            VOID DETECT = NO,$
  • What about using RELMEAS? Relative measurement. Measure some feature that WILL BE at the same relationship to the 'tiny' feature, and let Pcdmis do all the hard work for you.
  • What about using RELMEAS? Relative measurement. Measure some feature that WILL BE at the same relationship to the 'tiny' feature, and let Pcdmis do all the hard work for you.

    +1

    I use this method all the time for "hard to get" features.
  • Well I do like to see the way people come up with code and use it ( I learn much from it ), this is a case of redundancy. There are many ways to skin this cat, one being relative measure, another making the center of the hole a temp origin.

    I give you marks for showing your work, but deduct a couple for the time it takes...lol

    I am sure this idea of this kind of coding will come in handy elsewhere though, good thinking !
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