Clearance Plane and Pass-Through Plane

Published by CMMXYZ on June 7, 2022

CMMXYZ Tech Tip:

Video tutorial on Clearance Plane and Pass-through plane in PC-DMIS.

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Welcome to another video on tech tips from CMMXYZ. In today's video, I would like to cover a basic and a popular option, PC-DMIS that many programmers use, which is clearance plane and pass through plane. What is clearance plane? Clearance plane is a virtual plane from the coordinate system whose distance is set by the programmer. Clearance plane command makes the probe travel in the set clearance plane when moving from one feature to another.

To explain clearance plane, I have imported a DEA virtual machine, placed the CAD model on the surface of the CMM, and created the manual alignment as clearance plane can only be used in DCC mode. Once DCC command is added in Edit window, we can activate clearance plane. To activate clearance plane, go to Edit, Preferences, and Parameters. In Parameters settings dialogue, Clearance Plane tab, we can find Active Plane and Pass Through Plane. Let's first set the Active Plane as Set Plus and enter a distance of 100 millimeters from the coordinate system. Let's keep pass through plane at zero, which will be explained later in this video. Check mark on Clearance Plane Active option to activate clearance plane apply, and then click on OK. A Clearance Plane command is added in Edit window.

You can see the clearance plane, which is created using Show Clearance Plane icon, which can be seen in Graphic Item toolbar. Click on the icon to see the clearance plane in Graphic Display window. Now, let's change the angle to A0B0 orientation. When the tip orientation is changed, a clearance plane command is added automatically before the change. This command line makes the probe move to clearance plane and then changes the angle. Next, I'll create two features on Z-plus work plane. We can see that clearance plane command is added to features.

Now, let's execute the program from DCC mode. You can see that the probe goes to clearance plane, which is set at 100 millimeters in Z-access before measuring every feature. Next, let's measure a hole on the front surface that is the Y-minus work plane of the part. Currently, our work plane is applied in Z-plus direction. To apply a clearance plane in Y-minus direction, we have to go back to Clearance Plane tab in Parameter settings and change Active Plane to Y-minus, and it'll create a clearance plane at a distance of -100 millimeters as the clearance plane is in minus Y direction.

Now, we can use pass through plane. Pass through plane defines a clearance plane that the probe moves to to get to the next work plane, then makes an angle change. After the angle change, the probe moves to the new clearance plane and starts measuring features. I'll set my pass through plane in Y-minus direction at a distance of minus 50 millimeters from the coordinate system, then apply the clearance plane definition and click on OK. A new clearance definition command must be followed by the tip command to properly define pass through plane. So, I'll go ahead and change the tip orientation to A90 B 180, and I'll create a circle on Y-minus work plane. Now, let's execute the program from previous work plane and see how the probe moves. The probe goes to Z-plus work plane and uses Y-minus direction as pass through, makes an angle change, and measures circle two.

To give another example, let's set a clearance plane in X-minus work plane and keep past through plane as Y-minus. Let's follow that by an angle change command, and I'll create a point feature in the notch. When running the program from previous work plane, we can see that the probe moves to X-minus work plane using Y-minus direction as pass through and changes the angle in the new clearance plane to measure the point feature.

This was a video on clearance plane and pass through plane. Thank you for watching the video.

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