Groan - you reminded me of the time when one of my jobs was to check the micrometers around the factory - they made packaging for cigarettes, cosmetics, toys etc.

Some would come along and have their instruments checked and set up right - others would let me check them but refused to allow for any adjustment even when I told them the drated thing was way off and had got loose bits that required sorting - so I would refuse to certify them and also not accept their approval of card deliveries until I had checked it myself. Others would hide in the Men's room when they saw me coming with the gagues and book.

With having to check the chemical content, pH and transferable odour as well did I need the extra hassle?

Some of those daft old bu**ers were lucky they didn't get a micrometer put where adjustment would be difficult, if not dangerous.

I think I might have realised why I pleat down to millimetre precision and get really worried if I find a quarter inch too much or too little left over after the first pinning down.