If you have been machining metal for a while the change to plastics can be a little daunting. There are some tricks to the trade and some basic things you need to know about thermal expansion, speeds and feeds and the use of coolant. The biggest thing to remember is that most plastics, especially those that are thermoplastic, will melt when they get hot enough. Thermosets won't melt but can be brittle to machine so they are a totally different problem. Since heat is the culprit you must machine each plastic with the knowledge that it will grow, sometimes very rapidly, and then shrink again after machining. Some materials have to be machined once, normalize at room temperature, and then go back for final cuts. Sharp tooling, properly designed tools, speeds and feeds are all critical so there will be a learning curve. TriStar offers a "Machining Plastics" seminar and design manual through their website. For even more tips, Ask The Experts - that's what they are there for! It's not rocket science but there are tricks to the trade!