View Full Version : 1.8 NPT tap

10-11-2006, 09:02 PM
hey i need to drill and thread a hole to accecpt a 1/8 NPT thread. looking at otters site for mounting a gauge it says a 1/8 NPT tap and a 1/4 dril do it.

what puzzles me is that 1/8" is 3.175mm, but this seams too small for a whole.

can someone please help me out. like what size hole o drill and wat size tap i need.

10-11-2006, 09:04 PM
1/8" and 1/8 NPT are 2 different things. Go to your hardware store and ask for a 1/8 NPT tap, you might have to go to the plumbing section.

10-11-2006, 09:11 PM
This has a link in it (http://www.sundragonpps.com/paintball_gauge_vert_adaptr.html) that'll take you to a drill and tap chart. National pipe thread is tapered, not a straight thread so the hole will be different than a straight through 1/8" tap and thread -

10-11-2006, 09:42 PM
Don't run the tap all the way through your hole, if you do you'll ruin it. If your not confortable with your ability to do it on your marker get a piece of aluminum or light steel and use it to experiment on. Most tap kits come with the recommended drill size to use. Run the tap till the first couple of threads on the tap are showing then back out the tap and screw in the gauge to check and see if it is about a 1/8 to 1/4 turn past being vertical (if not run tap in a little further) that way when you put thread tape on and tighten the gauge it should be vertical and give you a good seal. If you get it vertical but not a good seal then you need to use a little more thread tape. Use soapy water to check for leaks under pressure. Good luck.

10-12-2006, 05:57 AM
use a Q drill or.332" for a 1/8-27 NPT. National pipe thread. when you use the tap leave 4-6 threads showing of the tap when you tap the block. use wd40 as a lube on the tap.