hello everybody

can you share how is your shop o lab calibrating the CMM machines?

we have 3 B&S CMM xcel, PC DIMS software, on site

thanks for sharing

Most people bring in outside contractors to calibrate them. Also, generally the manufacturers lock out the error maps so it's fairly difficult to return anything found out of spec back.

If you just want to validate your linear dimensions, some block stacks set along all 3 axis in multiple locations can do that.

For your volumetric calibration, most of the time I see a ball bar setup used. A laser is also often used to check the linear dimensions when we bring in someone from the outside.

how about when the calibration fails?

Most people bring in outside contractors to calibrate them.

Yes, generally a reputable outside contractor will not only verify the dimensional calibration, they can do any of the prescribed preventive maintenance that may be appropriate - such as internal cleaning, change air filters, etc., that you might not get around to, be aware of , or be trained to do.

how about when the calibration fails?

If you have an outside calibration source who is approved by the machine vendor s/he would have the ability to modify the internal error maps. That is the difference between calibration and validation.

Does the CMM calibration sphere requires calibration as well?

Yes, since the accuracy of that sphere is directly related to your probe qualification it should be calibrated. Many outside calibration sources can check the spheres in house instead of needing to bring someone on site like the CMM requires.

when I question the CMM operators about this, they told me that the probe has a plastic tip and they assumed the wear is minimal therefore calibration is void....

are all the probe tip made of plastic?

CMM probe tips are usually made from artificial ruby or Silicon Nitride (a type of carbide that is mostly used when scanning Aluminum castings). I have never seen plastic used.

It's not necessarily damage that you're looking for, the sphere could be thermally expanding/contracting and not be correct without any visible damage.

Now I'll be somewhat honest, unless you are concerned about micron level tolerances you could ignore it to save some money, but it's $150 for a calibration and I have mine on a 2 year cycle.

Also, (on Calypso/Zeiss, possibly others) if you use disc shaped probes you will want a certified ring gage for setting them.

The tips as mentioned are not plastic but glass which has a coefficient expansion of zero. The probe will wear and must be changed out periodically. If you view a probe under a microscope you will see evidence of wear.

As far as an outside calibration service if they are not able to adjust the mapping software then it is only a verification that the machine meets the OEM specs. If you purchase a Renishaw Ballbar kit you can do this yourself and save your money. It is best to have the OEM or their agent come in an do the calibration for obvious reasons. Changing the mapping software should not be left to just anyone.

Mark Boucher

The tips as mentioned are not plastic but glass which has a coefficient expansion of zero. The probe will wear and must be changed out periodically. If you view a probe under a microscope you will see evidence of wear.

As far as an outside calibration service if they are not able to adjust the mapping software then it is only a verification that the machine meets the OEM specs. If you purchase a Renishaw Ballbar kit you can do this yourself and save your money. It is best to have the OEM or their agent come in an do the calibration for obvious reasons. Changing the mapping software should not be left to just anyone.

Mark Boucher

Where are you finding glass stylii? I'd be interested in looking at their web site to see what advantages they claim, especially with regards to scanning on cast iron and aluminum.

For scanning on aluminum I use silicon nitrite this has the best wear of any of the probes when it comes to aluminum.

Mark Boucher

Agreed, it doesn't get that buildup either. For scanning aluminum castings (unless there's something I'm unaware of) you can't go wrong with silicon nitride. I got some literature a while ago when Zeiss was trying to push diamond probes. I have not heard of them in a while, but I could see the use if you had really rough cast iron castings that you wanted to scan.

We have gone to an in house calibration, or rather "certification" as was accurately noted earlier. We use a calibrated QuikChek Master to check the volumetric in all three axes and then we also do a full blown MSA. Both of these are done annually. Not only does this save scheduling a day for an outside source to come in for calibration it saves us a bunch of cash, which makes everyone happy. We've been doing this on both of our CMMs now for three years with no problems. If we were to have an issue we would be required to call in the pros from outside. I hope that helps! :agree1:

We have gone to an in house calibration, or rather "certification" as was accurately noted earlier. We use a calibrated QuikChek Master to check the volumetric in all three axes and then we also do a full blown MSA. Both of these are done annually. Not only does this save scheduling a day for an outside source to come in for calibration it saves us a bunch of cash, which makes everyone happy. We've been doing this on both of our CMMs now for three years with no problems. If we were to have an issue we would be required to call in the pros from outside. I hope that helps! :agree1:


Interesting, are you following B89 or the ISO-10360 procedures? What size is your QuickCheck master you are using? What size CMM? Is your company ISO registered? Is your QuickCheck sent out periodically for accredited calibration?

No. Actually, most of the tip probes are made of ceramic or ruby. The calibration of probes with reference ball usually compensates the wear, but this has limitations when tips have cracks or little scratches.