Use 7/64 as tap drill and 9/64 as clearance drill
americanNPT pipe thread i want how much taper it has depends on the pipe size/diameter
acquire correct tap from hardware or automotive supplier. Drill smaller hole through EGR port boss on head. Drill larger hole , size stated on tap to same depth as on intake port. then tap. If metric thread tap cannot be acquired a tapered pipe thread tap will also work. Threads are very close and will seal because of taper.
Wrong Question... You first determine the hole size required for the mine plan and then based on the air capacity and pulldown capacity of the drill rig you can determine the optimal drill pipe diameter to achieve productivity from the drill. What size is your drill? Air Capacity in CFM, Pulldown Capacity. What size does your drilled hole (diameter and depth) need to be to suit the mine plan (for the drill & blast process)?
Thread size refers to the diameter of a threaded rod or pipe. In the case of 0.125 Inch NPT thread, the 0.125 Inch refers to the nominal inside diameter of the pipe that the thread will fit into. This means that the thread is designed to fit a pipe with a 0.125 inch inside diameter.
It is called a Die. It looks like a nut that is used on a bolt. It is made from much harder steel and cuts the grooves in the pipe like the thread on a bolt. The same thing is used to cut the grooves on a bolt, a different size one for each size of pipe or bolt.
To effectively drill holes in PVC pipe for irrigation, use a drill with a sharp bit that is the same size as the desired hole. Mark the location of the holes on the pipe, then drill slowly and steadily to avoid cracking the PVC. Clean any burrs from the holes to ensure smooth water flow.
We use a die of the proper size to cut threads on steel pipe. This pipe die can be turned by hand, or by machine. There are examples of this process in any good hardware or large home improvement store. They have pipe threaders on the premises, and they can thread most common pipe stock.
5/16ths fine thread
If they are self tapping screws, the drill bit is as thick as the solid barrel of the screw. If you want the screw to go through easily to have a nut on the other side, then the drill bit is slightly larger than thread size.
Unified National Fine as opposed to UNC - Unified National Course
NPT (National Pipe Thread) and IPS (Iron Pipe Size) fittings differ in their thread design and compatibility. NPT fittings have tapered threads, while IPS fittings have straight threads. NPT fittings are commonly used for general plumbing applications, while IPS fittings are typically used for larger diameter pipes. To determine which is more suitable for your specific project, consider the pipe size and application requirements.
You could go to your local auto parts store and purchase a thread repair kit the correct size you are looking for. The kit will supply you with directions and what you need to replace the damaged threads with an insert of correct size for aprox $20. All you should need is an electric drill and drill bits.