The problem encountered being to come and control, on a conical part, an interior diameter greater than the opening through which it must pass. So we had to design an instrument that retracts to pass, and then deploys while keeping the nominal rating to control. the difficulty being to always fall back on the nominal dimension each time the instrument is deployed.

The problem encountered being to have to control, at the same time, two internal diameters of a conical part and this on variable heights.

The problem is to come and control a bore on a horizontal lathe and this without removing the tailstock of the lathe. So we had to make an instrument and its transfer standard, capable of "bypassing" the tailstock.