I have been asked to measure lead on a cylindrical machined surface. Is PC-DMIS capable of this measurement, and if so how would you go about programming the measurement?
If you have an analogue scanning probe, you can do a linear scan in the axial direction along the first 2 inches of the cylinder. Measure the cylinder with as high a point density and as many levels as is practical to achieve accurate results (for both the size and orientation of the cylinder) and then construct an adjust filter from your scan, using the Cylinder measurement as the reference input:
PC-DMIS Help Center - 2023.1 (hexagonmi.com). This will correct any 3D error induced by the probe drifting in and out of section as you scan. You can now dimension profile of your adjust filter and turn on graphical analysis so that you can visually see if there is any lead or not - this essentially replicates the optical comparator check. You can also level to your cylinder, rotate from the cylinder centroid to the adjust filter, select the appropriate workplane and construct a 2D line from your adjust filter. You can then dimension the angle between your 2D line and the cylinder axis.
The HUGE caveat with all this though is that you need to take into account the total measurement uncertainty of your system. +0/-0.05° over a 2" length is quite a tight tolerance to hit and, depending on what CMM and probing system you are using, you may find it is not accurate enough.
If you have an analogue scanning probe, you can do a linear scan in the axial direction along the first 2 inches of the cylinder. Measure the cylinder with as high a point density and as many levels as is practical to achieve accurate results (for both the size and orientation of the cylinder) and then construct an adjust filter from your scan, using the Cylinder measurement as the reference input:
PC-DMIS Help Center - 2023.1 (hexagonmi.com). This will correct any 3D error induced by the probe drifting in and out of section as you scan. You can now dimension profile of your adjust filter and turn on graphical analysis so that you can visually see if there is any lead or not - this essentially replicates the optical comparator check. You can also level to your cylinder, rotate from the cylinder centroid to the adjust filter, select the appropriate workplane and construct a 2D line from your adjust filter. You can then dimension the angle between your 2D line and the cylinder axis.
The HUGE caveat with all this though is that you need to take into account the total measurement uncertainty of your system. +0/-0.05° over a 2" length is quite a tight tolerance to hit and, depending on what CMM and probing system you are using, you may find it is not accurate enough.
