Probe stopping 'mid air' - Drives off

[[Ja...]]

Hi all

Any advice on probe just stopping in mid program (different stages), and drives turning off. Its as though something has obstructed it, but yet there has been no collisions. I have also cleaned the X, Y & Z scales with no success. I am met with a '418 Problem with floating mean value formation' error.

See below;

 

Thanks

Jack

[[Cl...]]

The error message doesn't look familiar. When this has happened to me, It was a dirty glass scale. I'd start there.

[[Ja...]]

What Clarke said, I've encountered a similar issue on our Duramax CMMs and a gentle wipe of the scales may be in order.

Edited May 1, 2025

[[Da...]]

Clean the air bearing surfaces, it could be dust creating a "drag" on the drive. Also check your air pressure coming in to your cmm.

[[Ja...]]

I've tried cleaning the scales already. What solutions are you guys using to clean? Wondering if there is somewhere else I am missing. I'll give it another try. 

 

Thanks for the responses so far.

[[Ja...]]

Also, what air pressure should it be running at? My machine is an ACCURA, 5 metre long. 

[[Da...]]

Air pressure should be above 80 psi. Also the scales and the air bearing surfaces are not the same. The air bearing surfaces are on the table and along the beam, and the scales are thin strips that look like copper ( on my Contura). I just use Isopropyl alcohol to clean with. 

[[Ky...]]

418 floating mean error is usually a probe head issue to my knowledge. When the sensor takes a points, its actually taking several, but it will only work if the values it measures is within a certain range (I do not know exactly what that range is off the top of my head). Checking scales and air pressure is a good idea, but I tend to doubt it would create a 418 error.

 

It could also be something with the measurement itself (like if the part is moving slightly while you are measuring it), but in general it is probably a probe head issue.

[[Wo...]]

I've had that issue on one of the XTRs when using the same stylus system for a long time, without stylus system changes. Over a few hours the stylus system would start to "shake" much more during measurement and if it became too much it would throw this error. I would just do an automatic stylus system change from time to time to somehow "reset" the stylus system.

[[Ja...]]

I've cleaned the X Y Z scales to death, using Isopropyl wipes, Granite Cleaner on the travel surfaces where the air bearings contact, checked air pressure which is around 75 PSI. Still no luck...Its bombed out while moving to home position now. Nothing to do with probe selection, its happened at various stages of the program, different probe each time. The part is a big 1metre long shaft which has been ran plenty of times, so I'm confident it isn't moving. Like I say, the machine stops and drives switch off in movement. Its hardware related it seems. 

In contact with a service engineer who hopefully will be able to help. I'll feedback here for anyone who is interested.

Thanks for your responses so far

Jack

[[Da...]]

Your air pressure needs to be above 80 psi. Can you adjust it up from the 75?

[[Ke...]]

Kyle is correct, the Floating Mean Value error means that the CMM cannot get the reading of the points to converge to a stable value. This is most commonly caused by a failing probehead, though in some scenarios such as poor fixturing or flexible parts it can be caused by movement  of the part itself during probing. As you have indicated this is happening at different points throughout the program, I would recommend verifying the stability of your part holding, but most likely you are seeing the beginning stages of probehead failure, particularly if it happens in midair. A few other things you could try include cleaning the contacts of the XXT probehead itself (VERY CAREFULLY), ensuring the attaching ring of the XXT to the RDS carrier is tight, and cleaning the contacts of the RDS carrier (VERY CAREFULLY). These do sometimes resolve this issue on systems running the RDS XXT

[[De...]]

Can you flip the switches on the different axis and see if the machine moves freely for the full movement range without tripping? I had a problem in the Y direction and what it turned out to be was a tiny piece of paper under the the left side of the machine and it would occasionally get under where the air bearing rides on that side. I couldn't see it until we took the covers off. This was a previous employer.