Need to Drill & Tap to get a barb to fit - Help Needed

[AFK_Matrix]

Hopefully this is a nice quick question.

I am going to be getting the Acrylic Aquatube when they come into stock. Now these have 1/8" threads and unfortunetly there are no 1/2" barbs that will fit. So going to have to drill out 2 holes so I can fit 1/2" barbs.

Now all I need to to is rethread the Aquatube to use 1/4" BSP thread. So what I want to know is what hole size to drill? Am I right in thinking I will have to drill a 11mm hole?

Thanks

 

[AFK_Matrix]

True but won't that mean I have a restriction in my loop? As its going from 1/2" down to 1/8"?

 

[AFK_Matrix]

Thanks Dave just what I was after.