M

I appreciate everybody's help in responding to my questions.
This is the first time I post here, and I couldn't find any posts that bring light to my issue below.
Some people at my organization are questioning the need for periodic calibration of surface plates ($ issue), or \the use of surface plates at all during inspection of the layout of duct assemblies we produce.
Inspections are currently performed on calibrated surface plates using all the usual gages (height, etc.).
The assembly's tolerances range between 0.020" to 0.030".
Questions:
1) Could we eliminate the need for performing this inspection on a surface plate?
2) Could we do some checks on the surface before inspection instead of sending the plate for calibration?
3) A vendor of a portable CMM (arm) is telling us that we won't need a surface plate to inspect the assembly if we use one of these arms, but I found some conflicting information elsewhere that indicates that inspections using portable CMMs do require a surface plate. What is your experience on this?

b/c it seems no1 stated the obvious (or I passed too fast on the posts and in this case mea culpa).