tap size, npt 1/8" Options

[rjbibeau]

i can't find the right drill bit size for the 1/8" npt anywhere. i checked the interent and found some charts and every single chart the i found has got either an R or a C for some reason. what the heck is up with that??? does anyone know the right size drill bit to use??

[wind]

since i work on a manufacturing floor and re-work is my specialty i can help you out....

measure the tap size, then find a bunch of drill bits. You usually want to drill a hole slightly smaller then your tap size. you want to have it small enough so that the teeth of the tap will be able to dig in and leave a thread.

in canada we use metric not imperial, so i cant help you with exact drill bit sizes.... if you use metric then i could help

1/8" is 3.175mm. So you would be using roughly an m3 tap.

when drilling metric you would go one mm less then your tap (unless your threads are large). so its an m3 hole you would us a 2mm to 2.5mm drill bit.

so you should be using a drill bit that is roughly .08 inches... drill bits that are close to that are 1/12" drill bit.... test it on scrap metal first.... you dont want to bust your tap on your car.... oh and use tapping oil and go slow!

one last thing.... all the holes on your car are metric... mabey you should get a metric set

This post has been edited by wind: Jan 12, 2005 - 2:43 PM