Looking to rotate the pipe? The first step you need to do is to drill the right size hole before touching the threads in the pipe.
But, not just any drill bit will do; you must choose the correct one to ensure accurate pipe threads that will ensure a tight seal.
In this article, I will explain what size drill bit you will need for your 1/8 pipe tap. Matching the drill bit to the faucet size is only the first step; you must follow best practices for drilling and tapping to ensure the job is done well. I’ve included some drilling and threading tips that you’ll find especially helpful if you’re new to these pipe cutting techniques.
So, let’s get started!
What is a pipe faucet?
Before discussing what size drill is best for 1/8 pipe faucetlet’s find out first: what is a pipe faucet and how does it work?
A pipe tap is a tool used to create threads inside a pipe during pipe fitting and machining applications. Threading the inner end of a pipe creates a female receiving pipe into which a male pipe is inserted to join two pipes, creating a tight seal.
Also known as threaded faucets, pipe faucets are made from alloy steel or a certain type of hardened steel, making it harder than most metal pipes.
The design of a faucet will vary from manufacturer to manufacturer. Some faucets are manual, with one end acting as a handle, while the other end has cutting grooves. With manual faucets, the threading process involves manual cutting.
More modern threading tools are constructed with one end having a lug or nut, while the other end is used for threading. This design allows you to mount the pipe faucet into another manual or motorized tool that helps turn the faucet, making the process less manual.
The tap process involves inserting the pipe tap into the end of the pipe and applying pressure while turning the tap. This is why the pipe faucet is constructed of harder material than the metal of the pipe; to cut the appropriate size threads inside the thread.
The grooves on the pipe tap have gaps that collect the cut metal, allowing you to discard waste as you thread the inside of the pipe.
The best rule of thumb when tapping is to ensure an even entry into the pipe. If you cut the pipe unevenly, it will be difficult to insert the male end of the pipe and the pipes would be joined at an angle, compromising the integrity of the seal.
What is a tap drill?
Now that we understand the basics of faucet and pipe threading, let’s look at faucet drills.
Before creating threads inside a pipe using a tap, you must first drill the pipe using a drill. A tap drill is a hardened drill that cuts holes in metal pipes.
When choosing a faucet drill, make sure it is the right size for the faucet you will be using to thread the inside of the pipe. The right size drill also ensures that there is no extra metal around the hole that would make it difficult to insert the tap for threading.
Tap drills are sized by diameter and length. The drill countersinks the hole, meaning the hole is slightly wider at the top and narrows as it goes deeper. The dip design accommodates the pipe tap tool, which has a slightly tapered tip. The tapered design allows you to place the pipe tap before starting the threading process.
What drill bit size is best for 1/8″ NPT faucet?
So, as I explained, matching the size of the drill to the tap you will be using to cut threads is an important first step. This allows you to drill the right size hole, keep the hole clean, and ensure that the faucet seats properly in the drilled hole.
If you have one 1/8» NPT Pipe Faucet, type R is the right drill bit to use with this faucet. If the pipe tap is tapered, the ideal drill bit size is 21/64 mm in fractions or 0.339 inches. For non-tapered or straight pipe tap, use a drill bit size of 11/32 mm or 0.344 inch. This gives 27 threads per inch.
Tips for Drilling the Right Hole for Your Faucet
A major mistake that novice machinists make is using the wrong size drill bit when tapping a pipe. While you can use charts to check the drill bit size you should use for a particular faucet, many of these charts are outdated and were used when machinists preferred to drill holes with a high percentage of thread height just to be safe
Also, in the past, many of the drills used for tapping holes were made of cobalt or high-speed steel. Instead, modern machinists now use more precise carbide drills. Carbide drills are more efficient and offer higher performance and accuracy than high speed steel drills. High-speed steel drills also make larger holes than more precise carbide drills.
The correct size tap drill ensures better threading results and generally eliminates the fuss of threading a hollow pipe. Tool manufacturers recommend increasing the diameter of the pre-drilled hole and applying thread values between 60 and 70 percent to increase the efficiency and longevity of the pipe tap.
Keep these tips in mind when drilling holes for the threads:
1. Store the drill bits with the respective pipe tap
First, once you match the drill bits to their pipe taps, it’s best to store them together. This ensures that you are using the correct size drill bit for each pipe faucet. The correct drill ensures that you are not making extremely large or small holes.
Excessively large holes may cause subsequent threads to be too shallow. On the other hand, holes that are too small can cause the tap to chip or bind, forcing it to remove more material from the pipe than necessary.
2. Anoint, anoint, anoint
Overheating is a potentially big problem when it comes to drilling and tapping pipes. Excessive heat can result in holes that are too large or small for the faucet size. A simple solution to this problem is to lubricate the drill bit with oil. Not only does the oil prevent overheating; It also helps clear debris, eases the drilling action and prevents the bits from making excessive unwanted noise when in action.
3. Start with a center drill
If you don’t have a lot of experience drilling holes in hollow pipes, it’s best to use a center drill bit before using the larger drill bit you chose for the 1/8 NPT pipe valve. The center drill allows you to create a small starter hole to guide the rest of the drill, making sure the drill is drilling in the right place.
4. Try to pinch to avoid overheating
Overheating is a major contributor to poorly tapped holes. An additional way to avoid the effects of overheating is to use the nibbling technique. Chipping involves drilling into the hole, then pulling the drill a bit to allow the hole to cool and remove debris. Turn the drill handle one full turn, then turn it half a turn in the opposite direction. Remove as much debris as possible when removing the bit and remember to lubricate the pipe surface as well as the bit.
5. Vary the applied force
Be sure to moderate the force you apply when drilling a hallowed pipe. Excessive force will damage the drill or result in an uneven hole, making it difficult to insert the pipe tap into the hole for threading.
How to use an NTP pipe faucet for best results
Whether you’re using a 1/8 NTP pipe tap, which requires an R or 21/64mm drill bit, or a 1/16, ¼ tap, etc., you should follow a few key principles for a perfect tap job. threading.
Here are some basic rules for using a pipe faucet:
Use high quality faucets
If you want high quality results, invest in the best faucets on the market. Use high-speed steel taps from a well-known manufacturer and replace worn taps with new, sharper ones. A boring faucet requires extra effort to cut the thread into the pipes. It can also cause the tap to chip or break while in the hole.
Place the faucet straight into the hole
For precise threading, carefully insert the tap into the hole. Make sure the faucet seats perfectly in the hole before starting the threading process. Aiming for a perfect start minimizes wear, tear and overheating.
Keep the hole free of debris
Tapping efficiency improves when you keep the hole clean and free of chips and debris. Pay attention to how the tap of the pipe feels. Any resistance is a sign of excessive debris that needs to be cleared. When this happens, turn the tap and pull out; this action will clear the chips, preventing binding of the faucet and clogging of the grooves.
Follow the valve alignment
Faucets usually come with guides that keep the pipe tap straight in the hole for precise threads. If tapping by hand, be careful to keep the tap fully aligned. On the machine tap, the pipe tap is automatically centered, but if you tap manually, tap misalignment is a real possibility.
Summary: What size drill bit for 1/8 pipe tap
Matching the right size drill bit to your pipe tap ensures efficient and accurate threading. An R type is the right size drill bit for 1/8 tap pipe, this equates to a measurement of 21/64mm or 0.339 inches. Keep in mind the drilling and threading tips we’ve recommended for the best pipe threading results.
