418 error

[[Pa...]]

We just had an error I've not seen before.  The CMM was running a well-proven program through lunch.  When we returned the stylus was in contact with the part, traffic light was red.  The error was "418: problem with sliding average".

I cleared the error and picked up where it left off.  The stylus made contact with the piece, the sensor (VAST Gold) gave the green light indicating contact, and... seven entire seconds later the machine registered the hit.  The machine moves normally and seems to be measuring fine, but every single-point-strategy cylinder in this program suffers from the same problem; it takes between 1 and 7 seconds to register a hit after contact.  It appears this only happens with this program as I was able to successfully re-run a piece from another lot of a different part number with none of the weird behavior.  There have been no collisions.  The machine has run 2 shifts 5 days a week since calibration two weeks ago.  It's an Accura2 with VAST Gold.  I saw planes run, both single points and scanned; no problem.  I saw 2D curves run without any issue.  I changed the affected cylinders to other stylus systems and the problem persisted.

I ran a qualification (Master Probe and another stylus), no issue.

All cylinders mentioned here are oriented along the Y axis and at very similar X/Z positions.  Probing forces and speeds are identical.

It's an obscure problem.  Is it familiar to anyone?

 

[[Sv...]]

The error points to a faulty sensor.

[[Ch...]]

Yes sounds like Sven says, the balancing from the Probe head ist failed. 😔

[[Be...]]

Is there a possibility that the part itself is rocking?  Is it supported only at 3 points?

[[Ja...]]

When I had issues similar to this (with a VAST XXT) what I discovered after months of trouble shooting was the sensor adapter plate was the culprit but this was happening over multiple programs and seemingly random frequency.

Turns out one of the contact balls on the plate was coming more and more loose over time but I had no way of knowing that until one day it just fell out. I replaced the sensor adapter plate and I haven't had the issue repeat at all. If you aren't having luck with other fixes replacing that may be worth a shot.

Edited yesterday at 04:16 PM

[[Ch...]]

If you perform a few automatic probe-tip changes and the probe head makes a humming sound or takes longer than usual to calibrate, the head is likely faulty. You might also want to try probing the reference sphere a few times to check for any variance in the probing results.