Internal and external threads can be made using conventional drilling, machining and semi-automatic end tapping. The higher temper alloys (such as T6 temper) give good quality results. Updated: December 10, 2012 Tip a friend Close Tip a friend Tapping To From Message Hi, I found the following article 'Tapping' on www.hydro.com and thought it might be of interest to you. Here is the link: http://www.hydro.com/en/Subsites/Extrusion-Ltd/Products1/Production/Fabrication/Tapping/ Close Contact Your message has been sent