Mounting part on setup tooling

Can't help you much with THAT software, but in the past, I have done it myself using a CAD package. You got use of one of them where you can build the "pieces" to the part model?

No, I don't. Is there anything out there for a reasonable price (read:free)? I only need it for this purpose.

Thanks

I want to bring models of knee blocks, 1-2-3 blocks, and other setup equipment in so I can program around real-world setups, allowing me to simulate datums, etc. I am finding the instructions in the Help screen very vague.

PCDMIS is metrology software. It builds inspection programs to CAD models/drawing data/actual parts. Like the others have said, you need software that creates 3D solid CAD models.

Some common fixturing is available under Insert > Hardware Def > Quick Fixture for Rayco, R&R, Teco stuff, like clamps, plates, standoffs, etc, but I think this area of PCDMIS is REALLY cumbersome to use. I can get those QFs positioned in PCDMIS, but it takes 7million mouseclicks and is therefore undesirable to me. It works, though.

But it sounds like you need models of common fixturing equipment. I'll bet that somebody has already done the work to make those and host them on the internet, and I'll let you use your Google-fu to find them. My question to you is:

Why do you feel you need these models? I have been programming offline for quite a bit, and the only time I've brought in the models of setup equipment was when a customer specifically requested it. Our ability to program in PCDMIS isn't impacted by the lack of the fixturing, for the most part, unless you have some intensely wild fixturing with multiple tooling balls or something like that.

Possibly you could post a picture of your model and your part and somebody could give you a workaround that doesn't involve bringing in foreign CAD models.

allowing me to simulate datums,

Why would you want to simulate the Datums? Does your print have you checking the part back to where the Datums actually are located and orientated off the part or to where your 1-2-3 blocks are positioned manually by error prone human hand?

PCDMIS is metrology software. It builds inspection programs to CAD models/drawing data/actual parts. Like the others have said, you need software that creates 3D solid CAD models.
....

All around good post, very informative.

Some of the parts we produce are long or thin and fairly flexible; they frequently need to be secured to a block or table to restrain them. This usually makes the primary datum inaccessible.

To achieve the same end, can I program using the actual model surface, then pick up the mating surface when the part is measured? What modifications have to be made in the alignment to do this?

Some of the parts we produce are long or thin and fairly flexible; they frequently need to be secured to a block or table to restrain them. This usually makes the primary datum inaccessible.

To achieve the same end, can I program using the actual model surface, then pick up the mating surface when the part is measured? What modifications have to be made in the alignment to do this?

If I read your post correctly, the necessary modification requires getting the design engineer to move the datum from the surface you make inaccessible with your fixture/setup to the surface you claim is the "mating surface".

If the GD&T on the drawing was originally done correctly, it reflects the necessary form, fit, and function requirements of the part and must be adhered to if you wish to remain compliant to the standard.

There is no magic alignment modification that allows you to just pick whatever feature is most convenient to be the datum.

Example: -A- is the back surface of a part. -B- is one edge, -C- is another. The part must be secured to a plate, making -A- inaccessible. I must use the plate to establish -A-.

I see 2 possibilities:
1) When creating the program, bring in my model mounted on a surface that I can probe instead of probing the actual part surface, or,
2) Program using the part model surface, then, when measuring the actual part, probe the plate and manipulate the alignment.

I seem to be getting responses wondering why I want to do this; isn't this a common scenario? I well know that I cannot just arbitrarily ignore the designed datum/feature relationships and controls, and it is not a matter of convenience.

it's not uncommon, but is also less than desirable, for the plate is not the actual datum. From a micron's perspective, that datum doesn't lay flat against the surface plate -- there are high points of contact that it is resting, due to it's deviation from perfect form. So no matter how you spin it -- it's not the same surface as the datum.

bad surface > poor alignment > poor dimensions > poor report.

While I THINK I understand what you're going through, you should really attach a picture, like I suggested before. Possibly somebody can recommend some sort of setup that will both rigidly fixture your part and allow you access to the features you care to align to or inspect. The first line of your last post does not do this.

Here's my assessment of your possibilities:

1) Bad idea. For the reasons I stated above, whereas the CAD and part will appear to lay perfectly on each other, in real life they don't adhere, due to manufacturing error. This will result in a poor alignment.
2) Not really possible to 'manipulate the alignment'. Don't forget that when you are taking hits on a surface, PCDMIS is using the CAD model's vectors to calculate probe compensation. IE: If you have a model of a 321 block, call Datum A the underside, fix it to a surface plate, program off the model, but then shoot the actual surface plate upon execution, what is going to happen?

PCDMIS is going to take your hit information off the surface plate (which faces up), and probecomp it according to the CAD vector information (which tells it that the surface is facing down). The result will be a surface that is off by the thickness of your probe radius, because we've inadvertently told PCDMIS to comp in the wrong direction.

The workaround that I've always used in this scenario when I have a Datum that (in this case) is flat against my surface block:

- create the plane off the model as expected
- edit the theoretical vectors to reverse them
- now that plane actually refers to the surface plate. it has the XYZ information that it (nominally) shares with the underside Datum, and the IJK information unique to the surface plate. So it will comp correctly.

however, you should make every effort to avoid cutting corners like this! I won't do it unless I've explored myriad setup options already. Good luck

Example: -A- is the back surface of a part. -B- is one edge, -C- is another. The part must be secured to a plate, making -A- inaccessible. I must use the plate to establish -A-.

I see 2 possibilities:
1) When creating the program, bring in my model mounted on a surface that I can probe instead of probing the actual part surface, or,
2) Program using the part model surface, then, when measuring the actual part, probe the plate and manipulate the alignment.

I seem to be getting responses wondering why I want to do this; isn't this a common scenario? I well know that I cannot just arbitrarily ignore the designed datum/feature relationships and controls, and it is not a matter of convenience.

mcultice & Collin, you are both exhibiting a great ignorance of GD&T. Because I am basically a pretty good guy, (Don't Tell Anyone!!!), I am going to try to teach you a little bit.


GD&T is a black art. Many of weak character dabble about generally doing far more harm than good. Those brave and stout enough of mind to strive for comprehension often fear there is a direct ratio that raises their insanity and anguish tat for tit with their growing knowledge. In short this is dangerous stuff best left to paid professionals.


Yeah, that means us. So let's start with a few definitions:


Datum = theorhetical entity of perfect geometric form that does NOT exist in physical reality.

Datum Feature = surface(s) of an actual part from which the Datum is derived.

Datum Feature Simulator = A imperfect fixture made precisely enough it's imperfections are ignored and it can be used to help derive the Datum from the Datum Feature. (examples of this would be a surface plate, or a gage pin, or a co-ordinate measuring machine.)



If you have not studied these ideas you should. I will not try to teach all of this complex abstract stuff in minute detail for free via the innerwebz.


You can secure the part to the plate, provided the plate is sufficiently flat to be a Datum Feature Simulator, and then probe the plate around the part to create the Datum. That is how it is supposed to be done. However I do not think you can pick points from the Datum Feature on the CAD to write the program offline. You will have to create vector points that appear to be in space in your graphics window offline, but that will probe the plate when actually executing the program. From those points create your Datum [A] plane that you will use in your alignment exactly the same as you would if you had taken the plane on the actual Datum Feature of the part.

Which is NOT the same as what I thought you were saying previously, that you secure the Datum Feature to the plate and then probe the OPPOSITE side of the part from the Datum Feature and use CAD nominals to Offset that to create the Datum. That is WRONG.