A letter v drill measures 0.3770 inch (9.576 mm). The closest fractional drill is 3/8" (0.3750") and the closest metric drill is 9.6 mm (0.3780").
What are the letter v drill equivalents?
| Drill | System | Decimal (in) | mm | Difference (in) |
|---|---|---|---|---|
| V | letter | 0.3770 | 9.576 | 0 |
| 3/8" | fraction | 0.3750 | 9.525 | -0.0020 |
| 9.6 mm | metric | 0.3780 | 9.600 | +0.0010 |
Drill sets that include this size
Number and letter sizes come in indexed sets; buy the set rather than single drills.
What speed should a letter v drill run?
| Material | RPM (HSS) | Feed (in/rev) |
|---|---|---|
| 6061-T6 aluminum | 2,026 | 0.0075 |
| 360 free-machining brass | 1,520 | 0.0068 |
| 1018 cold rolled steel | 811 | 0.0057 |
| 304 stainless steel | 405 | 0.0038 |
Starting points from conservative HSS drilling speeds. Small drills often call for more RPM than a benchtop drill press offers; run at the top speed and feed gently. Use cutting oil in steel and stainless, and clamp the work: never hold it by hand.
Cutting fluid for drilling
Frequently asked questions
What is a letter v drill in inches?
0.3770 inch, which is 9.576 mm. Letter drills run from A (0.234 inch) to Z (0.413 inch), continuing upward from the number drills. If you do not have this exact size, 9.6 mm is within 0.0010 inch.
What tap uses a letter v drill?
No common UNC or UNF thread uses it as its standard 75% tap drill, but it often serves as an alternative drill for a slightly different percentage of thread, or as a clearance or pilot size. The tap drill chart lists every standard pairing.