Don’t know if there is anyone on here associated with filament manufacturing. Centerless grinding is a relatively cheap and simple method of getting very precise diameters with very tight tolerances, and I was wondering if anyone uses it in their manufacturing.
http://www.efunda.com/processes/machining/grind_centerless.cfm#through-feed_grinding
I worked at a plant where we used it to hold diameters to 0.0001" or 2 micron tolerances. For filament manufacture, the continuous twisting would be a problem, and it seems too dirty and abrasive.