How To Handle Down CMMs?

Thanks for the advice. That is what I figured we would have to do in the event our CMM goes down. 

We have what is called "Positive Recall". Like BigMac, we tag all sample parts for later run on the CMM. Parts in production are tagged/placarded as Positive Recall. They can continue in production if all other inspection checks/criteria check out OK. They can't be shipped until the CMM verification on the tagged part(s) check OK. A down CMM is a rarity. Calibration/verification only takes three or four hours. So down time is minimal. Repairs, if they are needed, are usually due to worn out probe bodies and heads. Any other repairs usually inidicates that the CMM is being abused, neglected or not being properly maintained/cleaned on at least a weekly basis. Our "newest" CMM dates to 2005 and is working on its third PH10 and second set of oil separators. It's never required a major repair. Our other two CMM';s date to 1985 and 1991. All three are in great shape and not being operated in true "lab" environment.

I work in a fabrication facility, there is a robot welder literally 30' from the rollup door leading to my CMM. We are in an enclosed room but it's not airtight, nor positive pressure which results in the finely atomized iron from the welding fumes all over the building permeating our entire lab. Any and all surfaces somewhat rapidly acquire a dusting of brown magnetic dust. Maybe someday they will invest in a better system, but it's been 15 years already, so I doubt it. Meanwhile we will keep the feather dusters handy to brush off our machines exposed scales.  At least they are perpendicular to gravity so the dust can't really settle on them as much.  

How often do you or your colleagues clean the scales? :)

Rarely. But I am in a nearly dust-free environment

it has been stated/reported that you should NOT clean the scales unless you are having a problem as you can do more damage than good by cleaning them 'all the time'

(edit) BTW, I have NEVER cleaned the scales on either of my machines, and the old Validator was in a 'gritty' atmosphere for decades, and that is for over 35 years

When they need it. 

If we ever come back online from this big refurb, we are about to hit 2 weeks overdue... We will start up doing weekly calibrations again and hit them with the feather duster before we start that. 

Where can we get the report/statement about scales cleaning ?  My old lady QA always show me how to clean the scales with 70% alcohol wiper. She believes in what the retired CMM showed her ... 

That would be good to know.
When I worked in a machine shop we had "sticky dust" due to all the coolant fumes and we did have to clean the scales on a regular basis with IPA. Proper ventilation and the health of your employees was contrary to profits you see... 

LOL... My machine stays within 20 feet from some small  welding machines. Whenever I clean the z scales which exposes to air weekly, I could see the black dust on the wiper.

What does IPA stand for ?

Isopropyl alcohol
Rubbing alcohol basically, like from the medicine section. 
Don't want to use the denatured stuff... it's not so good for the life of your scales, or you job..

my cal-tech told me that.  the mfg of the scales for YEARS said to clean them regularly, then they all started to fail due to almost anything wearing the clear-coat off the scales and that unless you were getting those dreaded X or Y or Z errors popping up, you should just leave them alone.  I was always just too 'scared' to rub on them with anything due to the way they were made.  No way I wanted to be the one responsible for removing the protective layer over the actual gold.  Even Hex is now stating "MAY HAVE TO" (the link won't open for me on my ancient PC)

my cal-tech told me that.  the mfg of the scales for YEARS said to clean them regularly, then they all started to fail due to almost anything wearing the clear-coat off the scales and that unless you were getting those dreaded X or Y or Z errors popping up, you should just leave them alone.  I was always just too 'scared' to rub on them with anything due to the way they were made.  No way I wanted to be the one responsible for removing the protective layer over the actual gold.  Even Hex is now stating "MAY HAVE TO" (the link won't open for me on my ancient PC)

I am required to clean weekly( Not sure what does clean mean?).  I did clean scales 2 times over half year(From July 1 last year).  to prevent "clear-coat off the scales", I would like to send Hexagon an email about how long does period mean here?