How to stage a large part through the CMM...

[FOG_Carter]

Hi All,

Here's my dilemma. We have a large part which is approx 420" (10,675mm) long and unfortunately our CMM is approx 276" (7000mm). How do I stage this through the CMM using one program? I seem to recall the 'equate alignment' being mentioned for this situation but I'm unsure how to use it. I never done anything like this before. If someone has a good, robust process I'd definitely like to see it.

Regards,
Carter

[Darrollh]

First of all, Go ARMY!!!! Lol secondly. You can use something called move part and equate the alignment. One of the guys here would have more info on that. My parts are usually small.

[DAN_M]

You use an equate alignment when you have a part that you'll need the operator to physically move during the routine. Most commonly if you have a long part. For example, I once measured hole patterns on an 8ft long plate on a 4-5-4 using equate alignments.

1) measure datums in position one. create alignment (I did A1)
2) move the part to wherever you want...but ensure that in this new position you can measure the same datums in the same places as you did in position 1
3) have the CMM re-measure those same datums in the same spots it did in position 1
4) create a NEW alignment (A3)
5) tell PC DMIS to equate the second one back to the first (insert/alignment/equate)

MOVE/CLEARPLANE
PLN1       =FEAT/CONTACT/PLANE/DEFAULT,CARTESIAN,TRIANGLE,LEAST_SQR
            THEO/<0,0,0>,<0,0,1>
            ACTL/<0,0,0>,<0,0,1>
            TARG/<0,0,0>,<0,0,1>
            ANGLE VEC=<1,0,0>,RADIAL
            SHOW FEATURE PARAMETERS=NO
            SHOW CONTACT PARAMETERS=NO
            MOVE/CLEARPLANE
CIR1       =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,IN,LEAST_SQR
            THEO/<0,0,-0.0624>,<0,0,1>,1.398
            ACTL/<0,0,-0.0624>,<0,0,1>,1.398
            TARG/<0,0,-0.0624>,<0,0,1>
            START ANG=0,END ANG=360
            ANGLE VEC=<1,0,0>
            DIRECTION=CCW
            SHOW FEATURE PARAMETERS=NO
            SHOW CONTACT PARAMETERS=NO
A1         =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
              ALIGNMENT/LEVEL,ZPLUS,PLN1
              ALIGNMENT/TRANS,XAXIS,CIR1
              ALIGNMENT/TRANS,YAXIS,CIR1
              ALIGNMENT/TRANS,ZAXIS,PLN1
            ALIGNMENT/END
            MOVE/INCREMENT,<0,0,1>
            TIP/T1A90B-90, SHANKIJK=1, 0, 0, ANGLE=-90
            MODE/MANUAL
            COMMENT/OPER,NO,FULL SCREEN=NO,AUTO-CONTINUE=NO,
            Take part and lay in Fixture's Position #2
            COMMENT/OPER,NO,FULL SCREEN=NO,AUTO-CONTINUE=NO,
            Put probe at read point (as shown). Press OK for CNC Measurement.
READPNT_1      =FEAT/POINT,CARTESIAN
            THEO/<-0.3,0,0>,<1,0,0>
            ACTL/<-0.3,0,0>,<1,0,0>
            READPOINT/
A2         =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
              ALIGNMENT/TRANS,XAXIS,PNT22
              ALIGNMENT/TRANS,YAXIS,PNT22
              ALIGNMENT/TRANS,ZAXIS,PNT22
            ALIGNMENT/END
            MODE/DCC
PLN2       =FEAT/CONTACT/PLANE/DEFAULT,CARTESIAN,TRIANGLE,LEAST_SQR
            THEO/<0,0,-0.3>,<1,0,0>
            ACTL/<0,0,0>,<1,0,0>
            TARG/<0,0,-0.3>,<1,0,0>
            ANGLE VEC=<0,0,-1>,RADIAL
            SHOW FEATURE PARAMETERS=NO
            SHOW CONTACT PARAMETERS=NO
            MOVE/CLEARPLANE
CIR3       =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,IN,LEAST_SQR
            THEO/<-0.0624,0,-0.3>,<1,0,0>,1.398
            ACTL/<-0.0624,0,0>,<1,0,0>,1.398
            TARG/<-0.0624,0,-0.3>,<1,0,0>
            START ANG=0,END ANG=360
            ANGLE VEC=<0,0,-1>
            DIRECTION=CCW
            SHOW FEATURE PARAMETERS=NO
            SHOW CONTACT PARAMETERS=NO
A7         =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
              ALIGNMENT/LEVEL,XPLUS,PLN2
              ALIGNMENT/TRANS,YAXIS,CIR3
              ALIGNMENT/TRANS,ZAXIS,CIR3
              ALIGNMENT/TRANS,XAXIS,PLN2
            ALIGNMENT/END
            EQUATE/A7, TO ALIGNMENT, A6

[FOG_Carter]

Thanks DAN_M! It'll be a few weeks before I'm done with the program, but unfortunately the CMM install and turnover won't be complete until October. There is one item I'm concerned about is Step 2, but you state:

"but ensure that in this new position you can measure the same datums in the same places as you did in position 1".

I will only be able to measure datum A, datum B and C will be inaccessible.

[Quality ish]

I'd imagine that you could also use a readpoint, after you've moved the part, and realign on an already established feature.

And, yes.

Go Navy!

(USS Wainwright
CG-28)

[FOG_Carter]

USS Bergall (SSN-667)

[Darrollh]

US Army 2nd ACR Celtic Battery Ghost Troop.

[Quality ish]

In the Navy, we had outlets and everything. We rarely used batteries...

Roll Eyes (Sarcastic)