Collapsible tubes are made by

The blank diameter used in thread rolling will be

Outside diameter of bush is turned using a mandrel. The mandrel diameter is maintained as $${30^{\matrix{ { + 0.000} \cr { - 0.050} \cr } }}\,\,mm$$ and the bore diameter is $${30^{\matrix{ { + 0.050} \cr { - 0.000} \cr } }}\,\,mm$$. The maximum value in $$mm$$ of the eccentricity on the bush due to the locating mandrel

Flatness of slip gages is checked with