I have a large, unsorted, quantity of potentially useful watch screws of all sizes and types. Unsorted... I also encounter many missing screws. How to reconcile this problem? Is there any kind of mandrel (similar to the Bergeon hand hole sizing tool) which can be used to identify the size of screw holes? - case screws are the most common culprits it seems. I realise this begs the question of thread pitch but it would be nice to have somewhere to start. Then I might one day attempt the sysyphus-i