Qualification - What's happening?

[[Ja...]]

I understand that when a stylus probes a part, the measurement it records is in relation to the Master Probe (an offset if you will). But, what exactly is the software doing or looking for when you're qualifying a stylus? Center of reference sphere to center of ruby? It was explained to me once (poorly) before, so I thought you guys and gals might be able to clear things up. 🤠

[[An...]]

Hello Jake,

The reference sphere takes a certain position, which must be communicated to the system, then the position of the reference sphere is determined with the reference probe.
Position, position and diameter of each further probe is then determined at the reference sphere, in relation to the center of the probe.

[[De...]]

When the machine is turned on and is homed out, a reference position is created. This establishes the machine origin point.

In order for measurements to be taken by different styli across different stylus systems, Calypso must be able to have known 'offsets' to the individual stylus tips on the different stylus systems in relation to the machine origin.

In order to make this happen the first step is establishing the position of the reference sphere in relation to the home position of the machine.

Basic geometry tells us that any two spheres will always have the same radius between their centers when they contact one another. So by probing multiple locations around the reference sphere, it is possible to determine where the center of the reference sphere is by determining the center of all the points probed.

The Master probe is used for this step because all probe 'offsets' are the distance from the center of the stylus tip to the center of the Master probe.

Once this is complete, the CMM 'knows' how far it moved in each axis to get to the Center of the reference sphere.

Now when the same check is performed using another stylus tip, Calypso can calculate the difference in how far it needed to move. The difference in movement in each axis is the 'offset' for this stylus tip.

Qualifying your stylus tips is updating the 'offsets' of each tip to the master probe.

When you measure your part, the points are all collected in machine coordinates and then converted to actual positions of where the 'points of contact' are on the part first based on the stylus tips 'offset' to the center of the master probe and then projected along the normal to the surface being measured by the radius of the stylus tip.