A #29 drill measures 0.1360 inch (3.454 mm). The closest fractional drill is 9/64" (0.1406") and the closest metric drill is 3.5 mm (0.1378"). It is the standard tap drill for #8-32 and #8-36.
What are the #29 drill equivalents?
| Drill | System | Decimal (in) | mm | Difference (in) |
|---|---|---|---|---|
| #29 | number | 0.1360 | 3.454 | 0 |
| 3.4 mm | metric | 0.1339 | 3.400 | -0.0021 |
| 3.5 mm | metric | 0.1378 | 3.500 | +0.0018 |
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 #29 drill run?
| Material | RPM (HSS) | Feed (in/rev) |
|---|---|---|
| 6061-T6 aluminum | 5,617 | 0.0027 |
| 360 free-machining brass | 4,213 | 0.0024 |
| 1018 cold rolled steel | 2,247 | 0.0020 |
| 304 stainless steel | 1,123 | 0.0014 |
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 #29 drill in inches?
0.1360 inch, which is 3.454 mm. Number drills get smaller as the number rises, so the next number up is a smaller drill. If you do not have this exact size, 3.5 mm is within 0.0018 inch.
What tap uses a #29 drill?
It is the standard 75% thread tap drill for #8-32 and #8-36. Tap drills are chosen to leave about 75% of full thread depth, the balance of strength and tapping torque that published charts use.