I love the volt meters. Where did you get them? If you can find some really flat knobs, that would be perfect. The tap you bought is NF -national fine thread 1/4. That's a bolt tap. What you want is 1/4NPT -national pipe tap, or G1/4 pipe tap. Both work for water cooling fittings. Pipe tap fittings are tapered, so you have to test fit as you tap.