Ive got a number of dd hi-fow barbs that are being wasted and am wondering where i could purchase some tapping bits (is that what they are called?) to make my res and dcc plexi top suitable for 9/16 thread barbs (i.e. the dd high flow ones). Ay you can tell, i dont know much about what im doing so any pointers would be appreciated (do i tap with a hand drill?)
Definitely DO NOT try tapping with a drill. You may have to drill out your existing barb holes (1/2" is the correct starting size for a 9/16-18 thread). Then tap the holes by hand. Dishwashing detergent makes a good lubricant when you're tapping plastics but you have to clean the tap after so it doesn't rust.
Well you need a 9/16-18 tap (18tpi, 9/16" dia); it's a standard fine-thread bolt size (at least in the states). I think the one you want is in the UNF section of the page linked to above. Which reminds me... I still need to get some BSP taps. You just can't find the darned things in the states.