Read Point Feature

[cmmguy]

I want to use the READ POINT feature to determine where the probe is currently located in the CMM Space AND I want to do this under DCC control. How accurate is this and is there a way to make the machine dwell while I take this reading?

Lets say that I have just measured a circle and the probe comes to rest after the final touch, then I take a read point. Is this Read Point taken on the fly as the probe is still moving or does the machine come to a halt before taking the point or is there a way to put a pause in to get this reading more accurately (accuracy in the range of ±.05").

[craiger_ny]

It should take the readpoint at completion of retract. You could give it a movepoint increment of 0, 0, 0 perhaps. I do not know if that will help or not. Fly mode I susspect would make things interesting.

[cmmguy]

Ok, the Move Increment would give me some dwell

[Peter Warcholyk]

cmmguy,

Just curious, what / why do you want to do something of this nature??
Please explain.

ZydecoPete

[bw_bob]

In my experience readpoints are best for starting off programs so you can go straight into DCC mode.

[cmmguy]

cmmguy,

Just curious, what / why do you want to do something of this nature??
Please explain.

ZydecoPete

Fair question.

-Old habits maybe.
-I dont completely trust Clearplane to do as advertised.
-I need to move to specific location in a single axis only (there is no ability to do a single axis move in PCDMIS.
-I write parametric programs and instead of always figuring things out completely, I can move around the part without hitting things.
-I also write completely automated programs (no operator intervention) and at the beginning of the program I like to make sure the CMM is in the right location before movement starts. You know, maybe the last part did not complete properly and the CMM is somewhere I dont want it.

Maybe there are other ways to do this and I am interested in knowing them. This is just one way that I have gotten used to.

In my experience readpoints are best for starting off programs so you can go straight into DCC mode.

Yes that is the traditional reason. It started on the Sheffield's and to stay competitive, I think it was later added to PCDMIS. And I use it that way also.

[Tested]

Try this

We do what you are asking every day and do not use any dwell.
MODE/DCC
MOVE/POINT,NORMAL,2516.3396,733.6685,-642.0497
MOVE/POINT,NORMAL,2516.3333,461.7372,-642.0447
MOVE/POINT,NORMAL,2948.9709,461.5702,-642.0598
MOVE/POINT,NORMAL,2952.4717,720.213,-832.5316
MOVE/POINT,NORMAL,2947.1987,720.2316,-832.5316
$$ NO,NEW START
L4 =LABEL/
WORKPLANE/XPLUS
PNT1 =FEAT/POINT,RECT
THEO/911.4438,251.2988,-746.2958,0,0,1
ACTL/2947.1987,720.2316,-832.5316,0,0,1
READPOINT/
MODE/DCC
A0 =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
ALIGNMENT/TRANS,XAXIS,PNT1
ALIGNMENT/TRANS,YAXIS,PNT1
ALIGNMENT/TRANS,ZAXIS,PNT1
ALIGNMENT/END
CIR1 =AUTO/CIRCLE,SHOWALLPARAMS = NO,SHOWHITS = NO
THEO/0,0,0,1,0,0,17
ACTL/0.355,0.0383,-0.638,0.9993397,0.0355762,-0.0073848,17.0016
TARG/0,0,0,1,0,0
A1 =ALIGNMENT/START,RECALL:A0,LIST=YES
ALIGNMENT/TRANS,XAXIS,CIR1
ALIGNMENT/TRANS,YAXIS,CIR1
ALIGNMENT/TRANS,ZAXIS,CIR1
ALIGNMENT/END

[cmmguy]

Thanks for your reply.

Without any type of dwell, how well does the ReadPoint grab the position during dcc moves. In your example, you have stabilized Y and Z and then only move the X 5mm. If you were to move XYZ about 30mm at the same time and then grabbed the ReadPoint, how close would the ReadPoint be to the last MovePoint executed?

Thanks

[Tested]

It seems to grab the move point numbers for the readpoint and have had no problems so far. It is close enough that I can put a 2mm tip into a a 2.35 hole on one prg I run.