error on scan

[ginnbob]

I got this error on my scan about cannot find nominals on hits. what would cause this?

[Schlag]

You in inch or MM ? I have made this mistake before ! Does it make it through the whole scan and then give you this error ? I would start with verify that the surface vectors are correct and that all the actual surfaces you are trying to scan were " selected " when you generated scan.

[mbatten]

You beat me to it!

[mbatten]

The CMM finds the nearest surface in your CAD model to the measured hit in order to figure out what direction it should compensate the probe diameter. The "find nominals tolerance" defines when it gives up - if no CAD surface is closer than that, it will give you that message.

Make sure that that number is at least half your probe diameter plus whatever variation you expect to see in the surface you're scanning. If you've increased to that point and even a bit beyond and it's still not working, make sure:

1. Your alignment is good.
2. The surface is where you think it is.
3. You're not slipping off the surface at some point. This one gets me sometimes - I'll be trying to get close to an edge, and if the edge break is a bit bigger than I expect, I'll get all kinds of whacky numbers at that point. Also, is there a hole that it's running over?

If you still have the box up, I would start by increasing that number by 50%-100% and checking "change for this run", and see 1) if it works (the box will come right back if it doesn't) and 2) if the resulting scan data looks right.