What size drill bit do you need for 1/4 by 20 tap?
What size drill bit do you need for 1/4 by 20 tap?
| To Tap This Size Screw Or Bolt: | Use This Drill Bit: | (Closest Fractional:) |
|---|---|---|
| 12-28 NF | #14 | 3/16″ |
| 12-32 NEF | #13 | – |
| 14-20 NS | #10 | – |
| 1/4-20 NC | #7 | 13/64″ |
What size drill bit do you use for 1/4 inch pipe tap?
7/16″
NPT Tap Drill Chart
| Tap Size | Drill Size | Tap and Drill Set |
|---|---|---|
| 1/4″ NPT Tap | 7/16″ Drill Bit | 1/4″ NPT Tap and Drill Set |
| 3/8″ NPT Tap | 37/64″ Drill Bit | 3/8″ NPT Tap and Drill Set |
| 1/2″ NPT Tap | 23/32″ Drill Bit | 1/2″ NPT Tap and Drill Set |
| 3/4″ NPT Tap | 59/64″ Drill Bit | 3/4″ NPT Tap and Drill Set |
What size hole do I drill for a 1/4 bolt?
4130). The chart below shows drill sizes up to 1 inch in diameter….
| Screw Size-TPI | Recommended Hole Diameter | Drill Bit Size |
|---|---|---|
| 1/4-20 | 0.2280″ | #1 |
| 5/16-18 | 0.2900″ | L |
| 3/8-16 | 0.3580″ | T |
| 1/2-13 | 0.4531″ | 29/64″ |
What size drill bit do I need for a 1/4 NPT tap?
How do you measure tap hole size?
As a rule of thumb, for Metric threads, the tapping drill can be calculated by subtracting the pitch from the diameter of the thread. eg for an M5x0. 75 thread the tapping drill is 5-0.75mm = 4.25mm. For Imperial (inch) threads the tapping drill size is calculated in the same way, diameter minus pitch.
What is the diameter of 1/4 NPT?
0.533”
As a general “rule of thumb” an NPT thread is approximately 1/4″ (0.25”) larger than its “name.” For a 1/4″ NPT fitting the “nominal” OD is 0.533”. NPT fittings are slightly tapered so the “nominal” diameter is the diameter in the middle of the threaded portion, as measured by the top (crest) of the threads.
How deep should a pilot hole be?
Drill until your pilot hole is the same depth as the length of your screw or nail. Many experienced do-it-yourselfers can eyeball the depth, but if you aren’t yet that experienced, you can use a drill stop to mark the appropriate depth.
