Axis of PCDMIS different than axis of CAD Part

[guillaume_martin]

Hello !

In our school, we have to draw parts with SolidWorks.

For what I know today, "CAD equals Part" aligns the axis of PCDMIS with the axis of the part : Z+ with Z+, Y+ with Y+, X+ with X+

If I draw my part with attention, I can draw it to align the Z+ of my part with the future axis of the probe when I'll do "CAD Equals Part"

But if I want to measure the both sides of my part :
- one time the Z+ axis of my part will have to be aligned with the Z+ of the probe (PCDMIS)
- the other time, Z- of [...] Z+ of [...] when I'll do "CAD Equals Part"

And if i need to measure an other side of the part, for exemple, Y+ of the part will have to be aligned with the Z+ of the probe in PCDMIS.

****ed ! Is there a solution ?!?

Thank you very much for you attention,

Guillaume MARTIN

Ps : Do I correctly explained my problem ? My english courses are so far away !!!

[Wes Cisco]

Hello !

In our school, we have to draw parts with SolidWorks.

For what I know today, "CAD equals Part" aligns the axis of PCDMIS with the axis of the part : Z+ with Z+, Y+ with Y+, X+ with X+

If I draw my part with attention, I can draw it to align the Z+ of my part with the future axis of the probe when I'll do "CAD Equals Part"

But if I want to measure the both sides of my part :
- one time the Z+ axis of my part will have to be aligned with the Z+ of the probe (PCDMIS)
- the other time, Z- of [...] Z+ of [...] when I'll do "CAD Equals Part"

And if i need to measure an other side of the part, for exemple, Y+ of the part will have to be aligned with the Z+ of the probe in PCDMIS.

****ed ! Is there a solution ?!?

Thank you very much for you attention,

Guillaume MARTIN

Ps : Do I correctly explained my problem ? My english courses are so far away !!!

You explained just fine. This is only a problem if you intend to program from the CAD model instead of the part itself. If you just program from print and part you do not need "CAD equals part" at all. If you desire to use the CAD model, you have a couple of options, you can rotate the trihedron of the CAD model to match the way the part will sit on the CMM table, (probably easiest). Or you can use F5 Part/machine setup to account for the differences. Someone else will have to chime in now because I almost never get a CAD model to work with. HTH

[c_bearden]

One simple way to do this is do like Wes said...rotate your CAD model inside Solidworks to match how the part will be setup on the CMM. Once you import the CAD model, you can select your datums and see where they lie from your origin.....then do an alignment at the very beginning of your program and offset your X-Y-Z axises to get your CAD model at ZERO/ZERO/ZERO.

Doberman

[Paul Sarrach]

Do not worry about how you use your Solid Works, because in the real world you will not get your CAD that way.

You should never use "CAD=PART". Use a Iteritive Alignment. If you are doing a off-line program all you have to do after you have a program and now you have a part,go into your Set Up and use the "CMM to Part". Place part on CMM and find which axis is which. Then you will have to "Ctrl E" each feature and add in your "Move To's" and "Probe Rotations"

If you are doing one online, just ,go into your Set Up and use the "CMM to Part". And start creating your program. Use a Iteritive Alignment

[rebeldude]

I have to agree with Paul. An iterative alignment will line your axises up just fine

[Brian Gudauskas]

There are many ways to handle CAD and PART alignment relationships.

1. CAD=PART. Pros: Taught in class. Fairly simple. Always works if you understand the concept. Cons: If you don't understand it, can mess up a program. Should always get this right before creating the rest of your program. Might be more work than necessary sometimes. Can't be undone (but can be redone).

2. Offline program method (can be used online too). Pros: Simple. Just program the features using CAD from the beginning. No need for any setup whatsoever. No need to use CAD=PART. PC-DMIS tracks everything for you. Cons: Hard to think of any.

3. Use Solidworks to setup your alignment the way you will use it. Pros: You might now Solidworks better than PC-DMIS. Cons: You still have to use some alignment on the CMM, so you don't really save any steps, you just make it easier to understand.

4. Use the new transform utility in PC-DMIS 4.0+. Pros: Does what CAD guys can do, but in PC-DMIS. Cons: Same as number 3, you still have to do an alignment of some kind.

5. Iterative Alignment: Pros: Can be very easy once understood. Perfect for target point alignments. Perfect for coordinate systems that are not understood, or aren't very local to the part. Cons: It's sort of a best fit alignment, which can be argued is not supported by blueprint. It can be overkill for what could be a simple 321 alignment.

Hope that helps!

[c_bearden]

Iterative alignments are overkill in my opinion. I never use them unless I'm measuring a flimsey part. Too many user interactions when a 3-2-1 alignment is suffice......

Again, just my opinion.

Doberman

[Matthew D. Hoedeman]

I use CAD=PART on EACH AND EVERY alignment program I make and I never have ANY trouble with it.

ON-LINE programming with CAD data:
1) Set the part/fixture/detail on the table how YOU want it to be, and place it so it will be in the easiest place and orientation for YOU to work with it. In the case of a fixture, what is the position that will make it the easiest for you to load/un-load part.
2) Rotate the graphic screen view until the data matches the way you have it set up (remember, towards YOU on the screen = UP on the table in MOST cases). THIS DOES NOT rotate the data, this only rotates the VIEW on the graphics screen.
3) Using the F5 setup options, set the CAD to machine axis so that they match. If the ROTATE block show y+ TOWARDS you, then Y+cad = Z+Machine (in most cases on most machines.)
4) Once you have all 3 axis set (you may only have to change 2 of them, and it will be 2 or 3, NEVER just one!) you can close the F5 setup window. NOW, set you workplane to the proper plane. If you will be measuring a plane on the top or base and then 2 lines on the sides (normally the Z workplane of the machine), you will need to use the workplane that is showing on the top of the rotate cube because the CAD to MACHINE setup actaully changes the axis of the MACHINE not the axis of the cad. So, if CAD Y+ = MACHINE Z+ and you have the cad-to-machine done right, you will need to start out in the Y+ workplane.
5) Measure the features for the alignment, a LEVEL, a ROTATE and a feature to use for the third origin (the plane and rotate feature will work of the other 2 axis)
6) Go into alignments. Level to the plane, rotate to the rotation feature (line, cylinder, cone) and set the origins, however they need to be. In this case, the Y origin gets set to the plane that you used to level the Y axis to.
7) YOU MUST know what each origin value SHOULD be. AND, if it is a negative value, enter it as a positive value for the axis offsets. When all 3 are done, click on CAD=PART and close the window.

3-2-1 are the easiest alignments to do. I have used them since Pcdmis DOS days, WAY before they had the iterative alignments, and they are VERY easy to use. You can even use CAD=PART when doing iterative alignments. It will NOT hurt the alignment, but it gives the user a visual confirmation that you are aligned to the cad data (you will see a check-mark under OPERATIONS / GRAPHICS DISPLAY WINDOW). Also, if you make a seperate ALIGNMENT program (especially when using a holding fixture for a part) that saves the alignment to an external file, it will make it a lot easier in the long run for YOU. You can make many different programs to do different operations on the part on the fixture without the need to align each and every program. You run the alignment program, it saves the alignment to a file, and ALL the other program pull up THAT alignment data to use.

[Mike N.]

2. Offline program method (can be used online too). Pros: Simple. Just program the features using CAD from the beginning. No need for any setup whatsoever. No need to use CAD=PART. PC-DMIS tracks everything for you. Cons: Hard to think of any.

This method by far is the easiest of all....like brian said

try this method from an OLD thread

http://www.pcdmisforum.com/showpost.php?p=12655&postcount=7

[guillaume_martin]

First of all, thank you very much for you all ! Alignment was for me like the deep night in the wild forest, and now, thanks to you, it begins to be a dawn in the clearing !

I use CAD=PART on EACH AND EVERY alignment program I make and I never have ANY trouble with it.

7) YOU MUST know what each origin value SHOULD be. AND, if it is a negative value, enter it as a positive value for the axis offsets. When all 3 are done, click on CAD=PART and close the window.

Dear Matthew,

Your method is great !

The only default I could see is the point '7' : I (the student) have to return in SolidWorks to measure the distance between the origin of the CAD Part and the origin we want to set in PCDMIS...

For professionals like most of the user of this forum, it's easy, but for beginners (like me and the students) who have all to learn, it is adding a step !

(I know the answer will certainly be 'No' but : ) I'd like to
1) Measure and construct the origin in the measurement space in PCDMIS.
2) Simply says for the alignment "I'd like that teh Z axis perpendicular to THIS PLANE OF THE CAD Part, the X axis is parallel to THIS SIDE OF the cas part etc etc".
To say it simply, I'd like to forgot this (stupid) origin of the CAD Part, what could seems to be esoteric for my student, and only use the 'concrete' surfaces of the CAD Part. (If we could say that a CAD Part is concrete... !)

If it is not possible, isn't any "easy measurement tool" in PCDMIS ? I'd like that my student don't have to return in SolidWorks to measure the distance between the origin of the CAD Part and the Origin of measurement...

But they maybe have to learn that a software is not like they dreamed, but like it is sold !

Thank you very much !

Guillaume

[guillaume_martin]

Hi !

Today, I tryed a method I never tryed, probably the most simple one for me !
I simply made my 'LEVEL ROTATE ORIGIN' by selecting the surfaces in "program mode", and then "OK", without making "CAD = PART" !

And I was totally surprised when I saw that my origin and triedron stayed at the place I wanted !!! (The origin did'nt go at the origin of the part !)

Is this method dangerous ?

Thanks a lot,

Guillaume

[rangerboat72]

4. Use the new transform utility in PC-DMIS 4.0+. Pros: Does what CAD guys can do, but in PC-DMIS. Cons: Same as number 3, you still have to do an alignment of some kind.

This way is AWESOME! Where the heck was this when I first started programming with the DEMON? It would have saved me months of headache...

[Ken379128]

So if I go into the Setup/part/machine and change the part axis to the machine axis. I should then be able to do cad = part and use the cad model for a profile of surfaces? Is this correct

[Ken379128]

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