11-30-2017, 10:30 PM
Lucky for me I haven't had to deal with Nylon much. Delrin is my plastic of choice. If using HSS, I agree it needs to be dead sharp. My normal "go-to" tool for finishing Delrin is a small 80° diamond carbide insert tool. Get the speed and feed right and it comes out glossy and smooth as glass. Get out of the sweet spot and it turns into a corn cob. 
I know if I push the speed too far the cut turns "muddy" after awhile when it starts to melt.
I don't know if you have ever watched any of "AvE"s videos on YouTube, but he has a knack for identifying types of plastic with a soldering iron based on the temperature that it melts at, and can identify reinforcement materials added (glass filled etc.) by the feel of the tip of the iron scraping across the surface. Not very family friendly, but he is entertaining once you get to know his "style".
I know if I push the speed too far the cut turns "muddy" after awhile when it starts to melt.
I don't know if you have ever watched any of "AvE"s videos on YouTube, but he has a knack for identifying types of plastic with a soldering iron based on the temperature that it melts at, and can identify reinforcement materials added (glass filled etc.) by the feel of the tip of the iron scraping across the surface. Not very family friendly, but he is entertaining once you get to know his "style".
Willie