Contura 6206 grinding noises

[[No...]]

One of our new Conturas 6206 develops a habit of making grinding noises when moving, mainly in the Y axis, but now it started in the X axis as well. The service guy said it's harmless, but if I had a gold nugget for every time I've heard that, I'd be a rich man. 🙄

Today there suddenly was an inexplicable offset in all stylus holders in the rack (VAST XT), so that none of the styli could be picked up proparly anymore and I had to re-reference all holders. We have the free version of the Smart Service dashboard running, so I checked if a severe collision or anything similar happened over the weekend, but nothing. Now I wonder if it may have to do with said noises.

Has anyone experienced something like this before?

[[Da...]]

Severe "grinding" noises are sometimes caused by the protection bellows of CMM machines. They settle in a wedged orientation and make those noises. On the other hand, I never had it happen on my Contura G2s, and as far as I know, all Conturas only have bellows in the Y-axis.

I’ve seen one machine with a bad air bearing, but even that didn’t make a grinding noise.

[[No...]]

I know what you mean, especially from our old MC 550 with its wooden housing and sturdy bellows 😃
But the Contura doesn't have any bellows at all, so I can rule that out.
No, it's a noise that comes from somewhere inside. The Y noise has a faint ringing, a bit like a wrench on a string being pulled across the granite, while the X noise is periodical and sounds like somebody rubbing on a surface with a piece of paper.

[[Ke...]]

I would also check the quality of your air to the CMM and monitor the pressure, I have seen(or I suppose heard) water or oil in the air lines of the CMM cause various atypical sounds

[[No...]]

The air pressure is ok and we have additional filters installed at the air outlet (but now that you mention it, I'm not sure if and when these were exchanged last time 😕 )

To me it sounds like a mechanical problem, i.e. something being loose or not in the correct position. A weaker version of the Y noise already occured a while ago and I was able to get rid of it by moving the axis back and forth a few times. But that didn't work this time. Unfortunately I was not present when the last maintenance took place, so I don't know what the service guy said exactly.

[[No...]]

Another question:
Suppose the probe head or the Z ram collides with something on its outside and the drives shut off. How is such an incident recorded? It's not a typical collision, so what kind of event would I have to look for in the Smart Services Dashboard or elsewhere?
Because since Monday I now have the second part program where I had to reestablish the base system because it was offset by up to 4 mm (!) from the part. Since we use fixtures on a magnetic chuck, I would expect a tenth of this at most.

[[To...]]

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Hard Collision, as opposed to a Soft Collision.
I believe a Hard Collision is also one that generates a probe deflection greater that X. (solve for X)

[[No...]]

My line of thought was always that soft and hard collisions are classified by speed: anything at or below 70 mm/s is soft, anything above is hard. Because that's also what Zeiss takes as the basis for warranty repairs.
As I already said, the dashboard recorded no unusual events over the weekend. The last action recorded (CMM stopped) was Saturday at 3 am and the next one Monday at 6 am. Monday morning was when the problems started (the noise however was there before). What else may cause a sudden offset that large, which also seems to have affected the stylus rack?

[[Da...]]

I am wondering (and I don’t know): Is the reference point on Zeiss machines determined by a movable physical switch rather than a marking on the scale?

I would imagine, such a random offset should be impossible. I wouldn’t let the service have a good night's sleep until they’d offer me a satisfying explanation for that.

[[No...]]

On our old Contura from 2001 the reference marks were magnets screwed (?) to the scales.
Back then we once had a similar issue where the offset varied every time the machine was homed. Since it had started shortly after maintenance, I asked the service if there could be anything wrong with the reference marks. They said no and that the marks weren't adjustable at all.
Thank god the tech guy they sent me afterwrads was quite experienced. When he went on a break I had a quick look on his notebook screen. The document he had opened was a detailed description of how to adjust the reference marks 🤠

Today I checked the positions of our magnetic chucks. They are locked in place with pins in the thread holes. But the measurements show an offset of about 1.5 mm in X. So there must be something wrong.

I'm going to call service and let them have a look at it.

[[Wo...]]

We've had an issue that every Monday our oldest Accura would home to a different position (and I'm talking about 10-15 inches short on either Y or X axis). We would have to leave it where it stops and then do RETURN-SHIFT-F12 on the controller so it would home again. After second home it would most likely home correctly. I have a ring screwed to the table all the time and every time the machined is homed the location of the ring is checked and compared to nominals. This way I know the machined homed correctly.
No idea what's causing this. It has been happening less recently, so I was suspecting some environmental problem.

[[No...]]

Regarding our Contura, I was told by tech support that it has no hardware stops anymore, so no reference marks or switches there at all. That reminded me of what the tech guy said who installed the other (identical) CMM: The new Conturas have no end switches, instead they detect the mechanical end stop purely by the increased power consumption of the drive. This is also checked as part of the final acceptance protocol.

[[No...]]

Here's a short update on the outcome of our case:
The grinding noises are gone. The service guy simply cleaned the drive belt and pulley (or whatever is inside).

The offset issue was more complex and we're still not sure it's finally resolved. The first tech guy they sent couldn't find anything wrong and just set a parameter in the controller to compensate the offset. But a few days later it was back - this time in the opposite direction. 😮
So they sent a second technician who analyzed the problem more deeply. In the end he replaced the whole controller because he had noticed the malfunction of a relay that was connected with the probe head. If that was really the problem is not clear yet. Only time will tell.