move points-can they track alignments??

[MJBolster]

I recently programmed some cylindrical parts with numerous grooves( o-ring, etc.) around the diameter. Some of the grooves were relatively narrow and deep and I needed to sample the groove walls as planes. I used move points
to work my way around the part to avoid colliding with other features. The long
axis of the part is horizontal to the work table to enable me to sample the most features per set-up. (I'm still very new to PCD and cmm's.) I have little understanding of incremental move points and have only fooled around with "regular" mp's. My understanding is that move points are "locked"
into the measurement envelope of the cmm and incremental mp's are from the last hit. The issue is that if my workpiece is not located real close to the programmed position the move points are out of whack to the features so I get collisions . We don't use repeatable fixturing yet. Is there any way to get move points to track the part alignment? Is incremental move point the only option at this point?

[why me]

what Kind of alignment are you using? and are you programing from cad? I program from cad using interive alignment and my move point track where ever I set up the part we do injection molding 1"2"3" blocks and two sided
tape are the two things I use most

[MJBolster]

Not programming from cad yet.

[MJBolster]

I have not checked out iterative alignments yet.

[Matthew D. Hoedeman]

Move points SHOULD be absolute XYZ values based on the alignment, to an exact 3-D point in space, no matter where the probe currently is

Move INCREMENTAL moves the probe incrementally in each axis based on the values used, no matter where the probe currently is.

So, both ways, it makes no difference where the probe IS, but depending on where it is will determine where it ends up after the move, depending on the type of move.

So, lets say, the probe is at X10.0, Y15.0 and Z20.0 (for both examples)

Move,Point of X11.0, Y16.0 and Z20.0 will move the probe 1 in X and 1 in Y and 0 in Z to the absolute postion of X11.0, Y16.0 and Z20.0

Move,Incremental of X11.0, Y16.0 and Z20.0 will move the probe 11 in X, 16 in Y and 20 in Z to the absolute position of X21.0, Y31.0, and Z40.0

[MJBolster]

Matt, I use the print button on the jog box for my move points after I move the probe where I want it. Are you saying that these points should track my active alignment no matter where I place my part on the table?

[Matthew D. Hoedeman]

Yep, they sure should, UNLESS this is one of those things that requires CAD=PART or an ITERATIVE alignment (which includes an 'internal' CAD=PART). Everything I do gets a CAD=PART, every time, no matter what I am doing, even if I am only mapping out hole locations in a block of steel. I even use them with ITERATIVE alignments, it is not a problem. I have never had any problems using CAD=PART, ever. I use them ALL THE TIME. The only visable thing I see when using it with the ITERATIVE alignment is that it prompts you to measure the alignment again (MEASURE ALL FEATURES NOW?).

[Bill **********]

You can test this very easily. Set a move point above your alignment. Don't move the probe, move your cursor below the alignment set the SAME move point. You will see that they do indeed follow the alignment. The move before your alignment will be in absolute machine coordinates, the one below will be realtive to your part alignment.

Edited to add the following:

I do a lot of local alignments when I'm setting SPC bushings and if I forget to recall my primary alignment and go merrily along my way, I can very easily crash (worst case) or get a machine parameter out of tolerence (best case). Move Points are definately alignment sensative. Be careful copying and pasting them for this very reason.

Bill

[Dannyrl]

I use move points a lot. I trust them more than clearplane. Every program I have has lots of move points. As Bill says, be very careful using copy and past with move points. If you copy a point from one alignment and paste to a part of the program with a different alignment, the probe may go anywhere. It will use the xyz from the origin of the new alignment.
DL

[MJBolster]

Thanks All!!!

Hope to get back to the CMM soon to check all this out again.

TKS-
MJB