Related question: is there any way to get NPT threads to be in the orientation you want? For example I hate it when the thermometer is not threaded in enough in the upright position, but can only be threaded another half turn, not a full turn, before it is too tight.
One thing I do know is you've got to be careful threading stainless. If you screw it up, it'll work harden and you can forget about getting it back out.
I've got another Idea. I've got a HF 220v spot welder. I could use that to 'dimple' (not actually weld anything, just make a mark) the side of my polarware at increments, to make a poor mans graduation. Again I'd be slightly afraid of screwing something up and burning a hole in the side of my nice kettle.