What size hole to drill for 8mm tap?
Metric Tap and Drill Bit Size Table
|Tap||Metric Drill||US Drill|
|5mm x 0.8||4.3mm||-|
|6mm x 1.0||5.2mm||-|
|7mm x 1.0||6.1mm||15/64"|
|8mm x 1.25||6.9mm||17/64"|
Metric Tap Drill Sizes and Percentages of Threads
|TAP SIZE||TAP DRILL||THEOR. % OF THREAD|
- Tapping is when you threads are cut into a hole. A die set is used to cut threads onto a cylinder (bolt). To use a tap or a die, first determine the number of threads per inch (TPI) of the part to be fixed. A gauge system that has a number of different pins can be used to calculate the TPI of a bolt or nut.
- The Pozidriv screw is an advanced version of the Phillips screw but the key difference is that: Phillips drivers have an intentional angle on the flanks and rounded corners so they will cam out of the slot before a power tool will twist off the screw head. The Pozidriv screws and drivers have straight sided flanks.
- Screwdriver tips are available in a wide variety of types and sizes (List of screw drives). The two most common are the simple 'blade'-type for slotted screws, and Phillips, generically called "cross-recess".
|To Tap This Size Screw Or Bolt:||Use This Drill Bit:||(Closest Fractional:)|
|8-36 NF||#29||9/64"|Tap size Threads per inch Drill size w/ taper pipe reamer 1/16 27 15/64 1/8 27 21/64 1/4 18 27/64 3/8 18 9/16
- The M8 will measure about 8 mm in diameter, more likely, just a touch undersize, (.31496") The M10, about 10 mm in diameter, (.3937") and the M12 about 12 mm in diameter, (.4724"). The "M" designates the bolt is Metric and the number after the M indicates the size. The number after that is the length.
- The actual diameter of an M3 screw is usually about 2.9mm, an M2.5 screw is 2.4mm and an M2 is 1.9mm. We give both the overall length and the thread length. The clickable size given in the menu on the left is the thread length in the case of pan head and oem wafer head but the overall length for the flat head screws.
Updated: 2nd October 2019