What size drill bit is used for M8?
2 Answers
m8×70 expansion bolts use a 12mm drill bit. Explanation of the reason: When drilling wall holes or concrete floor holes with an impact drill, the drill bit used should be 4mm larger than the expansion bolt. Expansion bolts generally refer to metal expansion bolts. The fixing of expansion bolts utilizes the wedge-shaped slope to promote expansion and generate frictional gripping force, achieving a fixing effect. One end of the screw is threaded, and the other end has a taper. Additional information: 6×60 means the total length is 60mm, the sleeve length is 45mm, diameter is 8mm, wall thickness is 0.7mm, and the surface is color zinc-plated; the screw length is 60mm, diameter is 6mm, the threaded part is 35mm, the bottom rod hammer is 8mm conical, and the surface is color zinc-plated.
I've been in the auto repair business for many years and have encountered quite a few issues like this. An M8 bolt refers to a metric 8mm diameter threaded bolt, commonly used for connecting engine components or body fittings. If you need to drill a hole for this bolt, for easy insertion while ensuring a secure fit, I'd recommend a drill bit size of around 8.5mm. The reason is that if the hole is too small, forcing the bolt in can damage the threads; if the hole is too large (over 9mm), the connection will become loose and unstable. The 8.5mm size is an empirical value that provides the right amount of clearance while ensuring solid fastening. In practice, it's advisable to measure the material thickness accurately, use carbide drill bits to minimize wear, and drill slowly to prevent overheating and deformation. For example, when drilling into auto body panels, apply some lubricating oil to protect the surface; if you're tapping to create a threaded hole, pre-drill with a 7mm bit first. The key is not to arbitrarily alter the dimensions, as it could compromise overall safety.
