Equate Alignment in PC-DMIS

Published by CMMXYZ on May 21, 2021

PC-DMIS Tech Tip: This PC-DMIS Video shows how to measure a part if the part is larger than the CMM working volume.

Welcome to another video on Tech Tips from CMMXYZ. Today, let's talk about an alignment function called equate alignment. The equate alignment function is used to match alignments at different part positions. This is typically used when there's a need to move the part on the machine to give access for the probe to measure features which cannot be reached in one-part setup. In other words, when the part is bigger than the CMM working volume, equate alignment can also be used to realign the part if we accidentally move the part during measurement process.

Let's use the equate alignment function to measure the large part which cannot be measured in one-part position. Here, I have part on the CMM that the probe cannot measure the holes at the right side of the part and placed at the current position. I would have to move the part in X minus direction so that the probe can access the holes. In position one, select the common features that can be accessed from both the positions of the part to establish an alignment.

For this part, I've used the top plane, side plane, and cylinder as feature references for the original alignment. After alignment, the origin moves to the center of the cylinder. Next, measure all the accessible features in the current part position. Then, move the part to position two where the right side holes are accessible. After moving the parts to a desired position, switch to manual mode to create and measure the features for the new alignment. The key is that the new alignment should have the same origin and axis orientation as the original alignment. In this example, we are again measuring the same feature references that we used on our original alignment. Create a new alignment using the feature references such that the original and axis orientation is the same as the original alignment. Then, measure the new [inaudible 00:02:20] features on the CMM. After measuring the new features, you can see that the caret is aligned to the new position. Note that if we don't have common features between two or more positions, we can use different features but make sure that the origin and access orientation is the same as the original alignment using offsets while aligning. Then go to insert, alignment, equate alignment. In Equate, Alignment dialog box, select Part moved on machine. Select the new alignment in Equate new alignment drop-down and select the original alignment, Align 1, in With original alignment, and press OK. This will instantly update the previously measured features to the new position, and inserts the new equate alignment command into the measurement routine. Now that the part is aligned and equated at the second position, we can measure the holes at the right side of the part. Switch to DCC mode and measure the holes at the right side of the part. Now, the probe moves to the new position and measures the created features.

The next option in the Equate Alignment dialog box is Part bumped. This option is used when the part is accidentally moved and the alignment is remeasured to update the machine coordinates. If the part is accidentally moved, then go to Insert, Alignment, Equate Alignment. In the Equate Alignment dialog box, select the Part bumped option and select the alignment to remeasure. After remeasuring the alignment features, all the dimensions and features are updated to the new position of the part, then we can continue programming the part. This was a video on equate alignment. Thank you for watching the video.

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