!st (Taper) 2nd and Plug (bottoming) Tap, these three taps are ideal for making Meccano threads (5/32" BSW) in brass, steel or a suitable plastic, the 1st tap gives you a start when tapping by hand, followed by the second tap, the plug tap is to finish of in a blind hole such as a screwed rod adaptor, you can start with the 2nd Tap if you are tapping with a machine, a drill press is ideal, unplug the machine and slacken the pulley belt, use the chuck for your tap, then pull the chuck round by hand, backing off every couple of turns to clear the swarf, this method will give you perfect parallel threads. (use a little light oil when tapping in steel )  use a 3.2 mm drill with this tap