What Size Drill Bit for a 3-48 Tap?

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The 3-48 tap is a versatile tap that is commonly used for a lot of materials. They are mostly used for CNC tapping which is probably why you’re here. If you wanna know what size drill bit for a 3-48 tap is, read more below.

What Size Drill Bit for a 3-48 Tap?

A 3-48 tap would need a size drill bit of 5/64 inch or a number 47 drill. In decimal, this is 0.0785 inches. The 3-48 tap is an NC like the 1-64 tap which means it belongs to the Unified National Coarse. The UNC or NC for short is a defined standard set of thread forms, sizes, and other variables.

It is commonly used in the United States and Canada. NC or coarse threads are deeper than fine threads like the ⅝ tap with a drill bit of 17/32” and 1-64 tap with drill bit size #53. The 3-48 taps are commonly used for general machine tapping or CNC tapping. They’re also good for tapping into most materials.

Tips for Using Small Drill Bits

Use a Drill Press

Drilling with small drill bits requires a lot of accuracy. With a drill press, your accuracy increases significantly and generally produces better results. Most drill presses are built with metalworking features.

It has features that make drilling with small drill bits easier. For example, it has a handle that results in the bit going down into the workpiece at an accurate angle, creating a precise drilling area.

If you’re going to work on a lot of small drill bits in the future, it’s not bad to invest in a drill press with many features related to drilling with small drill bits.

Never Force the Drill Bit

It’s not a good decision to force the drill bit through the material most of the time. The speed of the drill bit won’t change even if you force it through, and it will only do more harm than good.

You also might end up breaking the bit if you’re being forceful. Small drill bits are usually brittle so you need to use them carefully. Forcing it through also blunts the bit’s tip, making it unusable.

In the end, you want to ensure that the drill bit you’re using is compatible with the surface. If it is and still doesn’t drill effectively, other underlying problems might need to be addressed.

Clamp the Material

Since small drill bits require a bit of careful handwork, you need your surface to be as stable as possible. Hence, you should definitely clamp it down to keep it from moving. Even with small drill bits will be hard if the surface isn’t steady. 

This is especially true in small workpieces. Clamps hold the workpiece or surface in place so you can drill without worrying about it moving. 

Think of clamps as an extra pair of hands that holds the piece for you so you can use both your hands to use the drill more accurately. There are many different drilling clamp accessories available in the market.


3-48 taps are part of the UNC and are commonly used since they can be used for a majority of materials. Make sure you use the right size drill bit at 5/64 inches so the tap will work properly and last for a long time.