Tap drills
M6 x 1.0 tap drill size
The tap drill for M6 x 1.0 is 5.0 mm, which is 0.1969 inches or 5.00 mm. That leaves about 92 percent thread engagement.
M6 x 1.0 tap drill, clearance and engagement
| Series | Metric coarse |
| Major diameter | 0.2362 in (6.00 mm) |
| Pitch | 1 mm |
| Tap drill | 5.0 mm (0.1969 in / 5.00 mm) |
| Thread engagement | 92% |
| Drill for 75% thread | 0.2042 in |
| Clearance, close fit | 6.4 mm (0.2520 in) |
| Nearest metric drill | 5 mm (0.1969 in) |
What M6 x 1.0 is used for
The most common metric fastener in machinery, bicycles, automotive brackets and flat-pack furniture inserts. The metric equivalent in size to 1/4-20, though not interchangeable with it.
If you do not have that drill
5.1 mm or 5.2 mm brings engagement down from about 92 percent to nearer 80 and 75 percent respectively, which is worth doing in stainless or in a deep blind hole.
How to tap a M6 x 1.0 thread
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Drill the hole
Use a 5.0 mm drill, 0.1969 inches or 5.00 mm. Drill square to the surface and clear the swarf on deep holes.
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Start the tap square
Start with a taper tap and check it is square in both axes within the first two turns. A tap started crooked will cut a crooked thread all the way down and cannot be corrected.
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Cut and break the chip
Turn forward about half a turn, then back a quarter turn to break the chip. Use cutting fluid on steel and stainless; aluminium and brass usually need none, though a wax stick helps in aluminium.
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Check the fit
Run the mating fastener in by hand. It should turn freely without side play. If it binds, the hole was undersized or the tap wandered.
Common questions
What size drill do I need for a M6 x 1.0 tap?
- The tap drill for M6 x 1.0 is 5.0 mm, which is 0.1969 inches or 5.00 mm. That leaves about 92 percent thread engagement. 5.1 mm or 5.2 mm brings engagement down from about 92 percent to nearer 80 and 75 percent respectively, which is worth doing in stainless or in a deep blind hole.
What is the clearance hole for a M6 x 1.0 bolt?
- 6.4 mm, which is 0.2520 inches. That is a close fit. A normal fit is one drill size larger and a loose fit two, and the looser classes are the sensible choice when the parts have to line up without reaming.
How is the M6 x 1.0 tap drill worked out?
- Subtract the pitch from the major diameter: 0.2362 inches (6 mm) minus 1 mm gives 5.00 mm, and 5.0 mm is the nearest standard drill. This is the metric convention and it lands near 92 percent engagement, not the 75 percent an inch chart targets.
Can I use a metric drill for a M6 x 1.0 tap?
- The closest standard metric drill is 5 mm, which is 0.1969 inches against 0.1969 for 5.0 mm. That changes engagement to about 92 percent, so check that figure is acceptable for your material before substituting.