Collision problems within features

[Schredder_Joe]

Hello All,

I've run into an issue I've never seen before and I don't know if it's something I'm doing within the routine or an issue with the CAD model I'm using. In 2 different locations of my part I have a Boss within a hole. 1 is an O-ring groove, the other is a port. The O-ring groove has draft angle walls so I'm trying to measure the walls as cones but when it travels from 1 hit to the next, the travel path is in the material on the other side of the groove (both ID and OD). The problem with the port is that when it's finished taking hits on the cylinder OD of the boss the probe path goes right back through the boss to come out of the feature.

These collisions are all showing in the path lines / collision detection (I haven't tried them physically). I am using Clearance Cube and I think I may be able to turn it off and add a clearance move to avoid that collision on the port but I don't know what to do about the O-ring groove. I included the info about the port because it seems unusual that the path of an auto feature would travel right through the feature with clearance cube on and thought that might indicate an issue with CAD model. The model was imported as an IGES file.

Thank you in advance for any help you can give.

[DAN_M]

Whenever my CMM is measuring a tight area, I turn off all of the automated stuff (clearance plane, clearance cube, fly mode, etc..) and make my own moves with "move/point" and "move/increment" commands. It takes all of the guesswork out of where I THINK it should be going and will go EXACTLY where I tell it.

[Schredder_Joe]

I do understand that those auto moves can be unpredictable but the problem with the clearance move is secondary. The problem that is stumping me is how to keep the probe from running into the OD when it's taking hits on the ID and vice versa. I know how to change the number and placement of the hits but no matter how I take the hits the probe moves too far back when traveling between hits and tries to move through the part. The groove width nominal is .120 - .125 inches. I know I can change from circular movement to a straight path but that only changes where it crashes. That is the only way I know of to change the path of travel. Is there another way to change that path?

[Mike Ruff]

Set SHOW CONTACT PARAMETERS=YES and set SHOW HITS=YES. You can insert move points in between the individual hits of your cone.

You can also play with PREHIT and RETRACT values if it is moving too far away before/after a hit.

[neil.challinor]

A few things to check.
1) Make sure your pre-hit and retract aren't set too high.
2) Check the void detection toggle. Sometimes the void detection overrides your hit placement.
3) Really obvious, but check the IN/OUT type is selected correctly.
4) Not so obvious - check the surface vectors of the CAD model for the area you're trying to measure (EDIT>GRAPHICS DISPLAY WINDOW>CAD VECTORS)

[RIDER]

Can you post a screenshot of the hit path or the code with the parameters?
Do you have collision detection turned on by chance?
If you click on the CAD with a vector point, are the vectors of the model correct?

[Schredder_Joe]

Thank you all for your ideas. To answer your questions: neil, Void detection is not activated, the IN/OUT are set appropriately, and the surface vectors seem to be correct.

As far as pre-hit and retract, in the global settings for the routine, they are set at 0.1 inches which would cut it very tight (the gap between the walls being 0.120"). Is there a way to change those settings for an individual feature or do the same settings need to be used for the whole routine?

Mike: I think you have my answer with move points between hits (if the prehit, retract option isn't the answer). Unfortunately I can't find information on how to do that. I can see the hit targets in the edit window for the auto feature but I don't see those targets in the code in the main edit window. How do you add move points in between?

Below I posted the code for the ID and OD of the O-ring groove and a screenshot of the OD path.

Thank you all again.

BACK PORT - UP-RIGHT OD=FEAT/CONTACT/CONE/DEFAULT,CARTESIAN,OUT
THEO/<4.636,3.539,3.386>,<0,-1,0>,5,0.058,0.731
ACTL/<4.636,3.539,3.386>,<0,-1,0>,5,0.058,0.731
TARG/<4.636,3.539,3.386>,<0,-1,0>
START ANG=0,END ANG=360
ANGLE VEC=<1,0,0>
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=4,NUMLEVELS=2,DEPTH=0.01,END OFFSET=0.01
SAMPLE METHOD=SAMPLE_HITS
SAMPLE HITS=0,SPACER=0
AVOIDANCE MOVE=BOTH,DISTANCE=0.394
ONERROR=NO,READ POS=NO
SHOW HITS=NO
BACK PORT - UP-RIGHT ID=FEAT/CONTACT/CONE/DEFAULT,CARTESIAN,IN
THEO/<4.636,3.539,3.386>,<0,1,0>,5,-0.058,0.989
ACTL/<4.636,3.539,3.386>,<0,1,0>,5,-0.058,0.989
TARG/<4.636,3.539,3.386>,<0,1,0>
START ANG=0,END ANG=360
ANGLE VEC=<-1,0,0>
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=4,NUMLEVELS=2,DEPTH=0.01,END OFFSET=0.01
SAMPLE METHOD=SAMPLE_HITS
SAMPLE HITS=0,SPACER=0
AVOIDANCE MOVE=BOTH,DISTANCE=0.394
ONERROR=NO,READ POS=NO
SHOW HITS=NO

Oring groove.png

[RandomJerk]

IIRC, prehit is the distance from the EDGE of the tip, not the center (one of the few times that is the case. So, if your prehit is .1 and your tip diameter is .04, then you're guaranteed to hit. As mentioned, you can change these settings as many times as you need to in the course of the program.

Another potential solution is to program as individual hits and stagger the ID/OD hits - if you're looking to take a hit every 60°, start the ID hits at 0° and the OD hits at 30°.

[Mike Ruff]

To adjust prehit/retract:
It is possible to adjust the prehit and retract as many times as you like in the same program. .1 inches is pretty big- I usually use .04 or .06 inches. To adjust it, put the cursor at the end of the feature where you want these changes to start. Hit ENTER, start typing prehit, hit TAB, type in the value you want to change it to. The process is the same for retract. You can change them back to previous values if you want to after the features too. It should look like this:

PNT205 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<2.7086,1.2876,-0.8045>,<0,0,-1>
ACTL/<2.7087,1.2876,-0.8047>,<0,0,-1>
TARG/<2.7086,1.2876,-0.8045>,<0,0,-1>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
PREHIT/0.04
RETRACT/0.04
PNT210 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<2.7228,0.681,-0.8045>,<0,0,-1>
ACTL/<2.7227,0.6811,-0.8047>,<0,0,-1>
TARG/<2.7228,0.681,-0.8045>,<0,0,-1>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
PNT215 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<2.7124,0.062,-0.8045>,<0,0,-1>
ACTL/<2.7125,0.062,-0.8047>,<0,0,-1>
TARG/<2.7124,0.062,-0.8045>,<0,0,-1>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
PREHIT/0.1
RETRACT/0.1
PNT231 =FEAT/CONTACT/VECTOR POINT/DEFAULT,CARTESIAN
THEO/<2.5141,1.288,-0.8045>,<0,0,-1>
ACTL/<2.5143,1.2882,-0.8047>,<0,0,-1>
TARG/<2.5141,1.288,-0.8045>,<0,0,-1>
SNAP=NO
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO

[Mike Ruff]

To insert move points, on the last line of the code you posted where it shows SHOW HITS=NO, change it to SHOW HITS=YES, and you will see the individual hit targets. You can insert move points in between these hits as shown:

CON1 =FEAT/CONTACT/CONE/DEFAULT,CARTESIAN,IN
THEO/<1.4764,1.4764,-0.03>,<0,0,1>,15,0.92,0.7087
ACTL/<1.4764,1.4764,-0.03>,<0,0,1>,15,0.92,0.7087
TARG/<1.4764,1.4764,-0.03>,<0,0,1>
START ANG=0,END ANG=360
ANGLE VEC=<1,0,0>
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=YES
NUMHITS=7,NUMLEVELS=2,DEPTH=0.07,END OFFSET=0.05
SAMPLE METHOD=SAMPLE_HITS
SAMPLE HITS=0,SPACER=0
AVOIDANCE MOVE=NO,DISTANCE=0.1
ONERROR=NO,READ POS=NO
SHOW HITS=YES
HIT/BASIC,<1.84,1.4764,0.04>,<-0.9914449,0,0.1305262>,<1.84,1.4764,0.04>
HIT/BASIC,<1.7031,1.7606,0.04>,<-0.6181558,-0.7751428,0.1305262>,<1.7031,1.7606,0.04>
HIT/BASIC,<1.3955,1.8309,0.04>,<0.2206172,-0.9665873,0.1305262>,<1.3955,1.8309,0.04>
HIT/BASIC,<1.1488,1.6341,0.04>,<0.893261,-0.4301718,0.1305262>,<1.1488,1.6341,0.04>
HIT/BASIC,<1.1488,1.3187,0.04>,<0.893261,0.4301718,0.1 305262>,<1.1488,1.3187,0.04>
MOVE/POINT,NORMAL<-1.0001,0.0578,6.1271>
HIT/BASIC,<1.3955,1.1219,0.04>,<0.2206172,0.9665873,0. 1305262>,<1.3955,1.1219,0.04>
HIT/BASIC,<1.7031,1.1922,0.04>,<-0.6181558,0.7751428,0.1305262>,<1.7031,1.1922,0.04 >
MOVE/POINT,NORMAL<-1.0001,0.0578,6.1271>
HIT/BASIC,<1.7687,1.1098,0.84>,<-0.6181558,0.7751428,0.1305262>,<1.7687,1.1098,0.84 >
HIT/BASIC,<1.3721,1.0193,0.84>,<0.2206172,0.9665873,0. 1305262>,<1.3721,1.0193,0.84>
HIT/BASIC,<1.0539,1.273,0.84>,<0.893261,0.4301718,0.13 05262>,<1.0539,1.273,0.84>
HIT/BASIC,<1.0539,1.6798,0.84>,<0.893261,-0.4301718,0.1305262>,<1.0539,1.6798,0.84>
HIT/BASIC,<1.3721,1.9335,0.84>,<0.2206172,-0.9665873,0.1305262>,<1.3721,1.9335,0.84>
HIT/BASIC,<1.7687,1.843,0.84>,<-0.6181558,-0.7751428,0.1305262>,<1.7687,1.843,0.84>
HIT/BASIC,<1.9453,1.4764,0.84>,<-0.9914449,0,0.1305262>,<1.9453,1.4764,0.84>
ENDMEAS/

[Schredder_Joe]

Thank you all so much, you've been so helpful. I think I'll be able to get this done now

[William Johnson]

Are you using circular moves between hits, then adjust the prehit retract.

[Schredder_Joe]

I was able to get this issue worked out using a combination of adjusting prehit / retract and putting some move points between hits. I hadn't noticed this last post until I was starting a new thread. Thank you again to all for the help.