Alignment Selection Modes (CNC)(Start)

[[Do...]]

Greetings all,

I am trying to find descriptions of the different mode settings under the Alignment Selection from the Start Measurement window. We've come up with our own internally, but I wanted to verify them against how the community interprets them and/or how Zeiss explicitly defines them.

Additionally, what do you guys typically use in your workplace setting? As we are working towards more repeatable fixturing setups, we have started to utilize the (Start) method for parts in production. Would this be the best method when establishing parts on AutoRun or would one of the other options be better suited?
 
Typically, you will see a list similar to this from the dropdown menu: (please feel free to correct these descriptions as needed)

Manual Alignment = Physically touching off the part
Current Alignment = Recalls the last used alignment for that given program (start or base)
ExampleProgram = Same as current alignment?
ExampleProgram (Start) = Last manual Start Alignment
ExampleProgram (CNC) = Last automatic Base Alignment
ExampleProgram (Start)(CNC) = Last Automatic Start Alignment

Any feedback would be greatly appreciated!

Cheers,
Don

[[Ri...]]

Manual Alignment = For manually locating the part. Prompts you to perform the Base Alignment/Start Alignment yourself, then will execute the Base Alignment in CNC mode.

Current Alignment = Will not run the Base Alignment again. Using the alignment calculated from the last CNC calculated Base Alignment. Should be used with caution.

Program Named Alignment = Executes the Base Alignment in CNC mode based off the last manual alignment of the Base Alignment. Used most commonly.

Program Named Alignment (Start) = Executes the Base Alignment in CNC mode based off the last manual alignment of the Start Alignment. Not commonly used, and should be used with caution.

Program Name Alignment (CNC) = Executes the Base Alignment in CNC mode based off the last CNC calculated Base Alignment. Commonly used, but should still be used with caution.

Program Name Alignment (Start) (CNC) = Executes the Base Alignment in CNC mode based off the last CNC calculated Start Alignment. Not commonly used, and should be used with caution.

I might be off on the (Start) ones as I have never used them, so that's my best take/understanding of them.

[[Mi...]]

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Agreed except Start Alignments should be something to learn for anybody not confident in them. If you have a complicated and/or Looped base alignment, you can use a start alignment to really speed up the part locating prior to the base alignment.

Base Alignment = all 6 DoF arrested, scanned features, looped.
Start Alignment = maybe only some DoF arrested, best taken with points - Rough part locating.

The Base Alignment is Relative to where the part is found during the Start Alignment. I use Start alignments that are shared across many programs for a given part or family of parts. I can move large numbers of programs to different CMMs and only have to perform 1 manual alignment. Each program has a unique Base Alignment, but Share the start alignment. It's certainly not what Zeiss intended but it saves me a ton of work.

Start Alignments can be set to run every time or only during a manual run then never again... depends how you want to use it.

[[DW...]]

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Single points are OK too. For the BA I do single points, for DRF I use scanning (unless there is a reason not too - small unstable radii etc).

[[Cl...]]

If you use high quality Poka Yoke fixturing that either doesn't move from its location or can be placed
solidly on/off at a specific location on the CMM, then single points for a start alignment are just fine.

[[Ri...]]

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There is a different between running a Start Alignment and running the Base Alignment via the program name alignment (start).

Start Alignments are great, and should be used for quick recovery of a manual alignment, especially in the case of complex Base Alignments.

I will disagree that Base Alignments have to be scanned features. This has been brought up time and time again, and I will disagree with it until the day I die.

[[Mi...]]

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Have to? No. But depending on the parts being made and the methodology of the programmer it often makes sense. Especially in high volume production where cycle times are scrutinized. I'm measuring machined parts, and I generally include the Primary and Secondary datums of the program in the looped Base Alignment. Obviously you don't have to, but it helps you have nominals that match basics without secondary alignments, it also reduces cycle time on partial runs or rechecks as it's most likely a rerun is happening due to somebody not liking the result they got from a position or something, if the datum is already being measured in the base alignment... it saves time.

I would refine my "Scanned features" comment to be "Stable features that you are measuring well enough that you don't have to check it again later in the program to use it in a characteristic"

[[Da...]]

My understanding is that the base alignment is only there to achieve a stable part orientation. No scanning needed, single points are just fine. Features used in characteristics follow GD&T requirements > always scanning.

[[Mi...]]

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There's lots of times where features used the Positions, Profiles, etc are completely appropriate to use points. Cones especially, you'll likely find much less in the way of calculation errors with point strategies.

But, the Base Alignment can do much more than just find the part, do it with stable features, strategy appropriate for the job, Filter/outlier, set it to loop, you could even set it up as a proper DRF if you want by setting the features to OTE and turning on ISO5459, and those features are now measured better than anything else in the program because of the loop so there's no reason NOT to use them for results.

It's an old, non-Calypso way of thinking to not use the Base Alignment features for results.

[[Ri...]]

Here's what I'll say, it is completely going to depend on the complexity and size of the part, as well as the function and Datum structure of the part. .

The most important function of the Base Alignment is to create a foundation for you to measure your part. If that comprises your Datums, and you can scan those features, go ahead and do that. Having said that, not every part that everyone makes is the CADCube, or a nice symmetrical part, or a part that benefits from this.

What do you do when the engineer puts crappy Datums on the drawing? In the automotive world my favorite was making Datum A a nice skinny cylinder. Make a 2 meter long tube, but Datum A/B are all on one side of the tube, and don't make up 25% the size of the part? Got a Passive Scanning head and you make plastic injection molded parts with deformations in the part? Measuring a part with huge tolerances? Got an inadequate fixture? Got inexperienced operators? The list goes on and on.

There is a polarization regarding scanning and touch-points in general. You should scan when it is appropriate and you should do touch-points when it is appropriate. I have said many times that anyone telling you that there is only one way to program Calypso has been living in a bubble.

I think what makes a great Calypso programmer is someone who has seen a lot of different types of industries/parts, and while they have a go-to method of programming the part, is willing to adapt their program to that specific part and their customer's needs.

[[DW...]]

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1000%. I am fortunate to see many industries, many materials. It forces you to think outside the box. The question I get daily is "Can we do this?" or "How would we do this?". Initially, I was very frustrated. Now I love the challenge.

[[Do...]]

I appreciate all of the replies, thank you for the great information!

[[Je...]]

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Donald,

I would agree with what the others have already said. You'll see a lot of feedback on this topic, because it's an important one. Feel free to ask any clarifying questions, if needed.

[[Br...]]

One thing to remember....

I open an existing program called widget make changes and save it as Router. The name of the Base alignment will stay at widget. So in this case, i will not see it in the pull down. You have to go into the base alignment and update the name.