Drill Bit Decimal Size Equivalents
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About Counterbores
![](https://www.mcmaster.com/prerenderstable/mvPRE/contents/gfx/small/a2bga60_abbr.png?ver=1276007986)
Counterboring—Enlarge the top of an existing hole to create a cylindrical-shaped opening with a flat bottom that acts as a seat for the head of a screw or wood plug.
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About Drill Bits
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Drill Bits for Spot Welds
![](/prerenderstable/mvPRE/contents/gfx/imagecache/264/2641n1-@halfx_636657036538037994.png?ver=imagenotfound)
Three drill points allow these bits to separate spot-welded panels without damaging the bottom panel.
Drill bits with flat on shank are used in spot-weld drills, such as Spitznagel.
For technical drawings and 3-D models, click on a part number.
Shank | |||||||||||
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Drill Bit Size | Decimal Size Equivalent | Overall Lg. | Max. Drilling Dp. | Type | Size | Point Style | Features | Specifications Met | For Use On | Each | |
Inch | |||||||||||
Uncoated High-Speed Steel | |||||||||||
1/4" | 0.25" | 1 9/16" | 0.04" | Round | 1/4" | Brad | Flat on Shank | NAS907 Type J | Steel, Iron, Aluminum, Brass, Bronze, Plastic | 000000 | 000000 |
5/16" | 0.3125" | 1 9/16" | 0.04" | Round | 5/16" | Brad | Flat on Shank | NAS907 Type J | Steel, Iron, Aluminum, Brass, Bronze, Plastic | 000000 | 00000 |
Metric Size Drill-Point Counterbores
![](/prerenderstable/mvPRE/contents/gfx/imagecache/294/29445a15-@halfx_637178861450282178.png?ver=imagenotfound)
The same tool lets you drill and counterbore holes with enough clearance for socket head screws.
For technical drawings and 3-D models, click on a part number.
Dia. | |||||||||
---|---|---|---|---|---|---|---|---|---|
For Screw Size, mm | Body, mm | Shank | Drill Tip, mm | Overall Lg. | Maximum Hole Drilling Depth, mm | Number of Flutes | For Use On | Each | |
Uncoated High-Speed Steel | |||||||||
6 | 10.71 | 5/16" | 6.35 | 1 9/16" | 9.52 | 2 | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | 00000000 | 000000 |
Metric Size Drill-Point Counterbore Sets
![](/prerenderstable/mvPRE/contents/gfx/imagecache/994/9940n113-@halfx_637673964888607589.png?ver=imagenotfound)
No need for separate tools, these sets have counterbores in various sizes that drill and counterbore holes with enough clearance for socket head cap screws. The longer the counterbore, the thicker the material it can drill.
Diameter | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Sizes Included | Number of Pieces | Body | Shank | Drill Tip | Overall Length | Maximum Hole Drilling Depth | Number of Flutes | Shank Type | For Use On | Container Type | Each | |
Uncoated High-Speed Steel | ||||||||||||
3 mm 4 mm 5 mm 6 mm 8 mm 10 mm 12 mm 14 mm 16 mm | 9 | 5.95 mm 7.54 mm 9.13 mm 10.71 mm 13.49 mm 16.66 mm 18.75 mm 21.82 mm 24.6 mm | 1/4" 1/4" 5/16" 5/16" 7/16" 1/2" 5/8" 5/8" 5/8" | 3.57 mm 4.36 mm 5.55 mm 6.35 mm 8.73 mm 10.32 mm 12.7 mm 14.68 mm 16.67 mm | 1 9/32" 1 13/32" 1 9/16" 1 5/8" 1 29/32" 2 5/32" 2 9/16" 2 27/32" 3 1/2" | 6.35 mm 7.54 mm 7.94 mm 9.52 mm 11.11 mm 14.29 mm 15.87 mm 16.67 mm 17.46 mm | 2 | Round | Aluminum, Brass, Bronze, Iron, Plastic, Stainless Steel, Steel | Plastic Case | 00000000 | 0000000 |
Hex Shank Taps for Drills and Screwdrivers
![](/prerenderstable/mvPRE/contents/gfx/imagecache/102/1021n13p1-a02c-digital@halfx_637177038975508274.png?ver=imagenotfound)
Insert these taps directly into drills, power screwdrivers, and other tools that accept a 1/4" hex shank. They're made of high-speed steel and are for use on most metal and plastic. All have a plug chamfer with 3-5 chamfered cutting threads, so they're suitable for start-to-finish tapping. When using them to tap closed-end holes, be sure to leave sufficient space at the bottom for chips to accumulate.
For technical drawings and 3-D models, click on a part number.
Thread | Drill Bit | Plug Chamfer | |||||||
---|---|---|---|---|---|---|---|---|---|
Size | Lg. | Overall Lg. | Size | Decimal Size Equivalent | No. of Flutes | Thread Type | Hex Shank Size | Each | |
Uncoated High-Speed Steel | |||||||||
5/16"-18 | 3/4" | 1 9/16" | F | 0.257" | 4 | UNC | 1/4" | 0000000 | 000000 |
Microstix Bits
![](/prerenderstable/mvPRE/contents/gfx/imagecache/277/2777n14p1-upa07-@halfx_637655836711101410.png?ver=imagenotfound)
![](/prerenderstable/mvPRE/contents/gfx/imagecache/a07/a07a-drivestyle-microstix-digital-master1574286323-p9@halfx_637098743020125216.png?ver=imagenotfound)
These bits have a 4 mm HIOS or half-moon shank. To fit in a 1/4" hex shank driver, use an adapter (sold separately).
For technical drawings and 3-D models, click on a part number.