G1/4 Mod For D5 1/2" & 3/8" Barbs
This mod was instigated by BP-Vincent at Bitspower so all credit to him
Very similar to a previous guide Tapping and Threading a G1/4 Hole but thought i would do a run through with the D5 to give a better idea of how it looks in practice.
Hopefully this simple guide will explain the tools required and how best to tackle the job.
11.8mm HSS Drill Bit
1/4" BSP 19 TPI Second or Plug Tap
400 Grit Wet & Dry
First of all you need to disassemble the D5 by unscrewing the front barb assembly from the pump itself and you also want to remove the pump bracket to make the job much easier.
Once you have the front off you need to cut the existing barbs off down to the Red line indicated in the picture below. You want to get this as precise as possible as this is where the rubber "O" ring of the barb will be seated so it needs to be as flush as possible. Don't worry if you're slightly off as you can always straighten things out with some 400 Grit Wet n Dry on a flat surface the way you would lap a water block base.
Once you're happy you have the existing barbs removed and flush you need to take a 11.8mm Drill and ream out both the inlet and outlet of the pump and its best to have the part clamped in some way as you need to keep the drill hole as accurate as possible or even better using a pillar drill. You will find the pump material drills really easy and i found i didn't need any lubricating at all but feel free to use it if preferred.
Now you have the 11.8mm hole, take your G1/4 Tap and basically start screwing it into the hole you have just drilled. Its paramount at this stage that you offer the Tap up to the hole perfectly vertical at 90 degrees to the surface otherwise you could end up with the thread running off and the barb not fitting flush resulting in leakage.
Keeping the Tap lined up correctly you can start Tapping the hole by turning the Tap half a turn clockwise followed by quarter turn anti-clockwise which allows the swarf to be released from the threads keeping the cutting edges of the Tap free to make cutting much easier – the process of half a turn clockwise followed by quarter turn anti-clockwise should be carried through till the Tapping process is finished. Again i found no lube was necessary but feel free to use it if preferred.
Its just a case of cleaning up, especially if you used any type of cutting lubrication and reassemble the pump and you're good to go.
The pictures below are first using 1/2" Danger Den Stubby barbs then the complete pump i used D-Tek Hi-Flow as the "O" ring stands less chance of popping out due to the recess "O" ring grove.