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Old Sheffield 9.9.7 Retrofit w/ New Renishaw Hardware vs New CMM.. Thoughts?


Jan 18, 2019
Debating on whether on not CMM retrofit is a good option for our current set-up

Our existing CMM is a 2004 Sheffield 9.9.7 CMM with PC DMIS. Support and availability of replacement boards for our machine is becoming scarce so we are looking to upgrade. I had originally been resigned to buying a new CMM, but recently became aware that retrofitting to Renishaw UCC control, new scales, PH20 head is an option. Seems that total cost of retrofit is somewhere in $35k-ish range. Our CMM runs on linear motors X/Y, w/ servo Z axis. Air bearings on all axes, and accuracy is still very good.

Two main intentions for upgrading the CMM:
1) Increase accuracy for diameter checks.
Ideally I would like to achieve an accuracy of +/- .00005" (+/- 1micron) on diameters smaller than 1.5" since we have a high volume order with diameters that are toleranced to +/-.00025" (6 microns). From what I gather, 5-axis probing a 1" diameter with PH20 may able to achieve that accuracy (even on retrofit) since the X/Y axes are not moving, only the Renishaw PH20 head.
2) Gain flexibility to use software other than PC DMIS.
We run high complexity low qty parts so CMM programming time is a bit of a bottleneck. (CMM Manager or Polyworks look enticing)
3) Parts, controller boards, etc are becoming scarce

Anyone here have thoughts or experience on CMM retrofits?
Do you think it is a good route to go?
I'm slightly torn since it is an 18 year old machine so putting modern hardware on it may not be worth it. At the same time, I'd imagine since all axes are on air there shouldn't be much wear and tear.
Last edited:

Milling man

Aug 6, 2021
Moscow, Russia
At the same time, I'd imagine since all axes are on air there shouldn't be much wear and tear.
I would start by checking the real state of the machine to understand whether it is worth investing in it or not.
Rent a multi-channel laser interferometer or something similar and get an error map for all axes. Then it will be already possible to understand whether it is worth spending $ 35k or not. In general, your idea looks great, if the machine bed is in order, most likely everything will go well.