I don't know if this was addressed, but the CMM itself will also expand/contract at the same time as your Inconel, but by a different amount. Unless it is ALL made of the same material, it may very well expand/contract differently in X/Y/Z, too! Knowing CTE of the target is only half of the problem. I am in an uncontrolled environment, as well, but have Temp Comp in the S/W, plus sensors on all 3 axes AND another sensor to stick to the target. It is probably a very complicated calculation, but the S/W does it. I would tend to not trust it (I am a very untrusting soul...) if it is more than like 15-degrees (F) from 68. At the very least, that philosophy saves me lots of work on the hottest days. Before we had Temp Comp, we had a tool standard. I long tool made of aluminum (much of what we CMM is aluminum) that has been outside-certified for length. As it got hotter (or colder), we would measure the length of the tool (both parallel to X and then Y), and compare that length to the certified length. That would give us a weird CTE (our CTE rolled the CTE of the target and the CTE of the CMM all into one Franken-number) that we recorded on paper. We ended up with a table of 'CTE' at each degree between about 60 and 90 degrees. It only worked for aluminum, though. TPTB didn't want to spring for another tool standard made out of Inconel, or for steel, or for titanium.
I don't know if this was addressed, but the CMM itself will also expand/contract at the same time as your Inconel, but by a different amount. Unless it is ALL made of the same material, it may very well expand/contract differently in X/Y/Z, too! Knowing CTE of the target is only half of the problem. I am in an uncontrolled environment, as well, but have Temp Comp in the S/W, plus sensors on all 3 axes AND another sensor to stick to the target. It is probably a very complicated calculation, but the S/W does it. I would tend to not trust it (I am a very untrusting soul...) if it is more than like 15-degrees (F) from 68. At the very least, that philosophy saves me lots of work on the hottest days. Before we had Temp Comp, we had a tool standard. I long tool made of aluminum (much of what we CMM is aluminum) that has been outside-certified for length. As it got hotter (or colder), we would measure the length of the tool (both parallel to X and then Y), and compare that length to the certified length. That would give us a weird CTE (our CTE rolled the CTE of the target and the CTE of the CMM all into one Franken-number) that we recorded on paper. We ended up with a table of 'CTE' at each degree between about 60 and 90 degrees. It only worked for aluminum, though. TPTB didn't want to spring for another tool standard made out of Inconel, or for steel, or for titanium.
