Equate alignment

[Tested]

I thought that the equate alignment needed you to measure and create a originial alignment. Then measure some features that your were going to use in your equated alignment. Next move your part as needed and remeasure these features that you checked while you were in the originial alignment.
next you create a new alignment from these. Then by selecting the equate alignment the new one is matched to the old one.

I read the help file and it doesn't seem to be saying this at all. Am I making this harder than it is?

[cmmguy]

I have just been looking at this myself. Although not tested yet, I understand it to mean that the Before Move Datum structure has to been "seen" or checked again in the After Move, then realigned and then the two alignments are "EQUATED"

[Tested]

I'm hoping that is not the case as I will not be able to reach the same features in the second alignment as I will use in the first, and if your going to measure the same features what would the "equatealignment" really do for you?

I think I'm missing something.

[Matthew D. Hoedeman]

This feature used to work MUCH better than it does now, just one of the enhancements to Pcdmis.

I have not tried to use it in the newer, messed up versions simply becuase I gave up tring to make it work the way it used to work.

This is how it used to work:

Alignment one, align the part, check the features, dimension them, etc. Then, move the part, make a second alignment. Once the second alignment is done (iterative, CAD=PART, whatever), you would use the equate function to equate the 2 alignments together. This would make all the previuos measured features 'jump' to the new alignment locations, along with their dimensions. This allowed you to use previously measured features, in their correct relationship to the NEW alignment.

[Tested]

So it does not allow you to use new features to get yourself back to the old alignment?

[cmmguy]

I'm hoping that is not the case as I will not be able to reach the same features in the second alignment as I will use in the first, and if your going to measure the same features what would the "equatealignment" really do for you?

I think I'm missing something.

The Equate Alignment box says New Alignment and Origin Alignment. It seems that the two alignments would have to be the same somehow. something that you can "SEE" in both setups. Maybe they dont have to be the actual real datums but some intermediary alignment. There has to be tradeoffs in accuracy, I guess, when you have to move the part.

So it does not allow you to use new features to get yourself back to the old alignment?

How would it know that they were related? The Equate box only lets you pick alignments. I guess they could be new features as long as they were visible in both setups and you set alignements on them somehow.

[Matthew D. Hoedeman]

The features (locations, types, etc.) didn't matter, as long as BOTH alignments were to the same 'cad position'.

See, I had a fixture (LONG long ago) that was almost 3 times as long as the machine with a part to match. The way I would check this part (today) would be to write 3 alignmnet programs, one for each fixture position on the table and check programs for each set up.

Using the equate alignment (at least, they way it USED to work, not sure about now) I could have done this with 1 program, BUT it would HAVE to be all one program. Alignment 1 for set-up 1, check what I could reach. Then move the fixture, make a new alignment IN THE SAME PROGRAM, do the equate of the new alignment (AL-2) to the original alingment (AL-1) after the second align was all done. Then it would 'snap' all the previously measure features to the 'new' alignment location. Check all the points I can now reach, then repeat for the third set up. It did not matter if the features weer the same or not, or even if you leveled to the same feature (say the first alignment was measure to a Z+ plane, the second could be to an X+ plane, made no difference).

[Tested]

From what I'm getting from it it does nothing more than adjust the dimensions you have already taken to a new alignment. It does not meld two alignments togeather. I thought I could measure alignment features and then measure some features that I would be able to get to once I moved the part , move the part measure these new features and do the equate alignment and it would adjust to my first alignment.

[Matthew D. Hoedeman]

That's what I am saying, that's what it USED to do, I do not know what it does these days. V3.2063 had an equate that worked SWEET. Alignment, check, move, make a NEW alignment, then equate the new to the old, and it looked (on the screen) just as if you have measured the previous alignment and check features from where the part is currently sitting, based on the second alingment you just made, even if they would be 5 feet off the end of the table.

[Tested]

If your are not measuring the same features "features not of your first alignment" in both before and after you move the part, what is it using to meld the two togeather?

[Bill **********]

Equate alignment works just fine after 3.5 mr3. You set up your initial alignment. within that alignment you have to measure features, NOT NECESSARILY your datums, that you can reach in your second alignment. In your second alignment you use the measured features as your NEW alignment features and then equate. This takes the deviations from the first alignment features and applies them to the same features in the second alignment. People get confused here because they think that they need to measure the same alignment features in both set ups, they don't. The new alignment features need to be measured as FEATURES in the first and Alignment features in the second.

Bill

[Matthew D. Hoedeman]

The CAD position. You tell it that the plane you leveled to in the first alignment is at Z100.5 and the line you measured is X+ with at Y-123.6 and that the hole you measured was at X125.3

This give you are CAD alignment (CAD=PART if not doing iterative).

Then you move the part. Now, you are leveling on the side of the part, not the bottom, once again, CAD DATA is what you are working to, and the SIDE levels to X+ at X500.3, your line for this alignment is Y+ with a Z value of -324.5 and the circle you measure has a Y valus of 500. Once again, CAD=PART, these values relate to the cad data.

All these features and the axial values of the features relate right back to the X0 Y0 Z0 of the cad file (which never changes). As long as YOU know what the features are and their values BACK TO THE 0,0,0 point, then you can equate the alignments, one to the other. It makes no difference if you have ANY features at X0Y0Z0, that location 'in space' exista for everything you do on the CMM, if you can reach it or not or if it is even in the same room. You have to know each features relationship BACK TO THIS 0,0,0 point. AS long as you know that, and you align to them correctly, then you can equate the alignment to each other.

[Matthew D. Hoedeman]

Equate alignment works just fine after 3.5 mr3. You set up your initial alignment. within that alignment you have to measure features, NOT NECESSARILY your datums, that you can reach in your second alignment. In your second alignment you use the measured features as your NEW alignment features and then equate. This takes the deviations from the first alignment features and applies them to the same features in the second alignment. People get confused here because they think that they need to measure the same alignment features in both set ups, they don't. The new alignment features need to be measured as FEATURES in the first and Alignment features in the second.

Bill

Yeah, see, THAT SUCKS. PRE-V3.5 you didn't have to be able to reach all the features in one set up. They could be completly out of reach of each other in each set-up, all you had to do was the 3-2-1 alignment, correctly, to get the equatre to work.

[Tested]

Okay Bill thats what I was hoping for but nothing in the help file or the manual says anything like that. And Matt was using it for something other than what I was after. I thought it should work as you are saying I just needed to hear it from someone I guess.

Thanks so much for the input.

[cmmguy]

Equate alignment works just fine after 3.5 mr3. You set up your initial alignment. within that alignment you have to measure features, NOT NECESSARILY your datums, that you can reach in your second alignment. In your second alignment you use the measured features as your NEW alignment features and then equate. This takes the deviations from the first alignment features and applies them to the same features in the second alignment. People get confused here because they think that they need to measure the same alignment features in both set ups, they don't. The new alignment features need to be measured as FEATURES in the first and Alignment features in the second.

Bill

The equate box asks for only new alignment and original alignment, how would that relate the two if you didnt somehow make an alignment out of the Pre-move features(I understand that these features dont have to be the "real" datum)