Agree with all the questions from nemanja, just wanted to mention there are nozzle tips designed specifically for nylon that will help. Making sure the material is dry is top of the list, But keep in mind Nylon 66 can be over-dried when dried for extended periods of time. Nozzle and barrel temperature are equally important. You can download some very good processing guides for all grades and types of nylon from Dupont plastics website.