r/Metrology • u/SrgntBallistic • 3d ago
PC-DMIS Pro vs CAD for Programming
First. I'm no expert in metrology or CMM. Very much a beginner and just started watching tutorials and product overviews this week.
[Pic for Attention]
A friend asked if I could look into learning how to write programs to do (semi) automated CMM for some parts his shop is making.
Currently they're running PC-DMIS Pro and the shop techs use it to manually check some crucial feature dimensions, datums, etc...
My understanding is that you can't bring CAD files or drawings into Pro...? You have to have CAD (or CAD++) for that.
Is it technically possible to write pretty thorough programs that can later be run with DCC (after manual alignment) with just Pro? My assumption is that it's possible but you have to interpret all of the features, datums, relationships etc... yourself.
Where CAD can help with a lot of that because it's baked into the CAD file, or you can bring in the drawings derive it from there.
Am I way off base with this? I'm watching through tutorials/training from Hexagon, CMMXYZ and others to get up to speed as fast as possible.
Any help is appreciated.
[Edit: any reason for the down votes? Is this not something appropriate for this sub?]
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u/ExplosiveButtPlug 3d ago
Don’t forget that you can get screwed if a drawing (which is now your only source of nominal information) happens to have “limited dimensions only” in the drawing notes.
Ex: a machined casting print will call out the nominals via reference dimension for a machined surface, but won’t contain the nominals for the as-cast surfaces
Only want to dimension those undefined areas is to go into a CAD software and query the model from there. Much easier to do it in PCDMIS. It also makes some functions near-impossible to use (iterative alignments, best-fit alignments), limiting the type of CMM jobs you can do.
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u/Tough_Ad7054 3d ago
You are on the right track. Programming without CAD is definitely a job best left to the “Pro”. It is possible, it is much harder and slower and you need to be an expert at reading drawings. It’s all math.
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u/stumpycrawdad 3d ago
I learned to program cmm's without cad. Got models like 8yrs later, just got mad as shit because it's cheating as far as my brain was concerned.
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u/Tough_Ad7054 3d ago
Me too, pard. I think the good thing about all our hard math work in the early days is that we realize that the CAD is just a numerical mask and the math behind it will always prevail. We can see right thru the Matrix of Metrology. 😏
I love using the model but sometimes do a program straight from the print, just to keep fresh, as it were. It still sucks.
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u/rotcivwg 3d ago
I second this. A couple years ago my shop got the exact machine pictured as our first CMM. I was tasked with learning how to program it. I’m a machinist and not an engineer and I think it would be much more difficult to program it without CAD. PC-dmis is pretty intuitive in summary mode with a CAD model to work off of.
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u/SrgntBallistic 3d ago
Thanks!
In talking with him about possibly upgrading to CAD, It kinda seems like a question of "where do you want to spend the money?"
In the time/effort/complexity of interpreting drawings, and possibly multiple doing iterations to get good working programs...?
Or the upgraded license.
I saw some posts in here talking about Metrology Mentor which seems to be able to use PMI/MBD write programs, maybe do some automatic pathing and collision detection.
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u/Tough_Ad7054 3d ago
He will save untold thousands by getting a PCD CAD license. Get an offline license and leave the machine as Pro. Frees up the machine and offline licenses are pretty reasonable.
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u/reav11 3d ago
One of the bigger issues with PC-DMIS pro is that there are a lot of things that are considered "sheet metal" features in PC-DMIS that are not supported in the automatic feature creation tools "Auto-Features".
The auto feature creation tool i incredibly limited ins scope so you IIRC you won't be able to create things like round or square slots, cones, edge points, auto planes.
It's absolutely possible to do all of that in PC-DMIS pro, and if you have a live machine and parts there is no reason that it can't be done. Doing it offline is a lot more complicated but still something that can be done.
But the latter isn't something I'd ask a beginner to do.
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u/ribeye256 3d ago
I used to program arms without CAD all the time in Delcam PowerInspect, now Autodesk. While not DCC, they were repeatable programs. That was for legacy stuff with no CADs available. When we switched to more model based, I switched to Polyworks and what a difference! So much easier with CAD models.
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u/f119guy 3d ago
It’s possible to write thorough cmm programs without CAD. It was done for decades. It’s a matter of making something 1000x more difficult and time consuming. The people I know who program a CMM without a CAD model are currently chained to their CMM.
Jokes aside, I have met 2 programmers who were somewhat efficient with programming PCDMIS without a model. They would usually need 1-2 weeks to get their programming dialed in enough to run a machine without crashes and be reliable enough to start gathering data for FAI, PPAP or just running off parts and making offsets. And they always ran into the minimal dimension drawing issues. They would open a CAD model in something like NX or Creo, export some vector data from a few points on the as cast/3D printed surfaces and then import the vector data back into pcdmis. Mind you, they’re programming complex parts, generally 9 datums or more and applying advanced GD&T.
I think getting a CAD++ seat is the way to go. Unless your friend has very simple parts, or has a very limited budget
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u/clavo21 3d ago
Yes you can program without CAD.