It is kind of terrifying seeing him operate so many machines with his tie dangling around his neck. He obviously knows his way a round a shop better than I do but I always thought neckties were no-nos in the shop.
Wearing them still isn't a good idea, but clip-on ties will at least break away when they get caught rather than forcing your head into some machine...
From the constant cuts to extreme close-up, I'm betting he puts on the tie and collared shirt for talking-to-the-camera shots (and one or two per episode where a machining tool is on, but he's carefully away from it) and takes it off most of the time when he's actually working.