Hard to get points.

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

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W0QNX over 12 years ago

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,$

Reply

W0QNX over 12 years ago

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,$

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