Cad = Part Setup

[Pablop]

I'm definitely a newbie here, I've only completed the first class, PC-DMIS Cad.

So, I'm a little stumped when I try to get cad=part to an iges model that has the y-plus in the cmm's z-plus orientation. That is, I've tried various combinations of aquiring points with the CMM set in Z-Plus, or Y-Plus, and aligning with various orientations, but I can't get the aquired points to lie on the part after I press cad=part.

Also, the pc-dmis manual is kind of light on explanation in this area.

If my Iges y-plus is the plan view (see attached jpeg), and the part is face up on the cmm, do I still have the cmm set for z-plus as I aquire a plane and two lines to align it.? Do I level the plane to Y-plus even thought the points were aquired with the cmm set to z-plus?

Help

[Matthew D. Hoedeman]

Well, first you have to set the machine=cad axis, just to keep things straight for Pcdmis.

F5 setup, then Part/Machine, then set X+ to X+ (which it should be already)
Then set CAD Y+ = MACHINE Z+ and Cad Z+ = Machine Y-

Then, set your workplane to Y+

Measure your planes and your lines (pick-ups on the detail).

Your plane should be in Y+, use that for level
Without knowing what you are measuring for your ROTATE, I can not help you, but if you measure the 'font' of the block, your rotate will be X+ about Y+
Then you need to set the XYZ 'zero' points. It looks liek the 'top' of the block is Y0, but I do not really 'see' a feature for the X and Z zeros. So, lets say that the left-fron corner is your pick-up points, we will say the X value of the corner is -6" and the Z value is Z6.0. So, you would set the X origin to the corner, the Y origin to the 'top' and the Z origin to the corner. Then, your OFFSET values would be X+6, Y0 and Z-6 (they always have to be the opposite of the actual cad value, don't worry about why right now). Then, after you have set your LEVEL, ROTATE, each axis origin, and offset each axis, you then click CAD=PART and every thig WILL snap right into position.


ONE NOTE: For the CAD to MACHINE axis to work right, it MUST be done the VERY FIRST thing when you create the program, BEFORE YOU MEASURE anything.

[DuaneSiders]

This is what I would do to set up this part.

1. Go to Edit/Preferences/Setup/Cad/CMM and make the following changes:

Machine X = Cad X
Machine Y = Cad -Z
machine Z = Cad Y

2. Change workpane to YPLUS

3. Measure a plane on top of the part

4. Measrure a line on front of the part from LEFT to RIGHT

5. Measure a circle in the large hole in the middle of the part.

6. Create a new aligment

level YPLUS to the plane
rotate XPLUS about YPLUS to the line
set ZORIGIN on the plane
set XORIGIN and YORIGIN on the hole
Translate XORIGIN to the CAD origin
translate YORIGIN to the CAD origin
NOTE: use the measured values for these translations and reverse the signs.

7. Selece CAD=PART (it now should on the screen)

8. Remeasure the plane/line/circle

9. change workplane to ZPLUS

10. Create a new alignment

Level plane2 to ZPLUS
Rotate Line2 to XPLUS about ZPLUS
Set ZORIGIN on plane2
Set XORIGIN on circle2
Set YORIGIN on cirlde2

11. Create any alignments needed to inspect the part and proceed.

[Pablop]

Thanks, I'll give that a try.

[Pablop]

Well, I just tried a quick round of the above and must have missed something, so Ill try again, but this raises another nagging question.

What is the best way to try cad=part more than once? Do I have to close the program, delete the cad file pcdmis created? Can I just delete the step and try again?

There's that whole warning about using cad=part only once, so I'm not sure what the best way is to try it over and over again until I get it right.

[Matthew D. Hoedeman]

Once you do CAD=PART, any cad file you then import will be 'married' the the alignment, just like the cad data you had in there. I use CAD=PART at least TWICE in every alignment program I make, I have NEVER had a problem with it. You can NOT un-do the CAD=PART, but you CAN change the values in the alignment (or the features) and do it again to correct a mistake you may have made or to tweak an alignment, especially for fixtures, to get the locators in tolerance. You can do it and do it and do it until you like what you are getting, but you can not un-do it.

[Mike N.]

I'm surprised nobody has explained the simple method

offline while in online mode:

1. import cad model
2. turn on program mode (ctrl+F4)
3. 3d rotate model on screen to equal how its fixtured on table
4. click on plane face to establish plane and press end on keyboard
5. repeat as necessary for other features to obtain an alignment
6. create alignment and rotate in alignment to necessary orientation
7. turn on dcc and repeat same features for dcc alignment
8. continue with program

[B. Jacobs]

Mike,
I just tried what you said. I think it worked. It was simple. I hope I did it correctly. I am going to save this info for the next time I have to import something.
Thanks

[Pablop]

When I tried this method I get the following:

1) In the graphics window, the probe tip is pointed along the Z-Axis of the part (Did you mean to included adjustment of the part vs. machine axis as per above, posts fist?)

2) If I click onto a surface, PC-DMIS seems to randomly try to acquire some feature of the plate (holes lines) anything but the planar surface.

I'm just way too new for this. Need to put the hours in.

[Mike N.]

When I tried this method I get the following:

1) In the graphics window, the probe tip is pointed along the Z-Axis of the part (Did you mean to included adjustment of the part vs. machine axis as per above, posts fist?)

the probe position in the graphics window wont make any difference. It will obtain the proper vector from the cad model and those vectors will make up the feature orientation for your created alignment.


2) If I click onto a surface, PC-DMIS seems to randomly try to acquire some feature of the plate (holes lines) anything but the planar surface.

I would check your settings for "surface mode" it probably isn't checked OR your model isn't created as a solid or "with surfaces"

I'm just way too new for this. Need to put the hours in.

It does work ....try and try again

[Jeff Hunt]

Do you face to set up the machine axis seperate for each part? I have some parts where the cmms z+ is the cads Y+. Other parst machine Z+ is the cads x+. Does the change go into the Default for all programs or is it part specific?

[Matthew D. Hoedeman]

It is SETUP specific. If you can not set the part up so the cad axis match the machine axis, you should do this setup procedure and do it BEFORE you measure anything.

[Jeff Hunt]

It is SETUP specific. If you can not set the part up so the cad axis match the machine axis, you should do this setup procedure and do it BEFORE you measure anything.

What differance will this make besides mirroring issues? I thought the CAD=PART really does the same thing.

[Matthew D. Hoedeman]

CAD=PART makes the alignment/machine/cad data 'married'. Doing the CAD to MACHINE is basically, PRE-ALIGNMENT, making the machine axis go the same direction (direction ONLY) as the cad axis. In the past, it was a 'helpful' thing for getting parts set up and aligned. Now, at least in V3.5, it was all but REQUIRED for you do to the regualr alignment, it would not be able to solve features correctly (if at all) unless it was 'looking' at the part as it sat on the table. I don't know if this has been fixed in V3.7 (or V4.0).

Example, the part sits with X+ to the machine Z+ axis. If you started the program, using machine numbers (which you have to for the alignment) and left it at Z+ workplane (matches the machine and the measurements you are taking) and measure the Z+ plane, then 2 lines on the edges, in the Z+ plane, then went and did the alignment, and leveled X+ to the plane and rotated Z- to the line on the front (which would be correct) and did all the other stuff, saved the program, closed, came back and ran it later, it wouldn't be able to solve the plane when you measured it. THAT is a P I S S E R, let me tell you.

[guillaume_martin]

4. click on plane face to establish plane and press end on keyboard

When I clic on a plane or a cylinder, a "UV" windows appears asking me how many points I want to measure in directions U and V.

Then, in the program, all this points appears : I have to construct the plane or the cylinder with this points (vectors).

How could I do to come back to your method : Clic on the surface then press "End", without that "UV" windows appears ?
(Is it a little checkbox to check !?!)

Thank you in advance,

Guillaume