This is a spiral groove cutting attachment for the famous 7x10, 7x12, 7x14 Chinese mini-lathes. It is mostly 3D printed and easy to make for anyone for the average machinist with basic 3D printing experience. This adapter is particularly useful to impart internal grooves in tubes. The cutter head is not included with the CAD model as it would depend on your desired diameter, but spiral guides for most common twist rates are. Simple cutter head is easy enough to make using the lathe itself though. may design similar tool youelf, but the time you would spend doing so would cost you more than just buy mine and edit it to your liking. The model here is a visual representation .stl only, enough to undetand how it works but not to reproduce it. Contact me if you need the complete CAD model in .stp or other formats as well as the cutter heads.