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8.5mm Drill Bit

When buying an 8.5mm drill bit for drilling metal it is important to buy the correct drill bit.

Drill bits for metal are available in many different materials. And the price varies greatly according to the type of metal drill bit.

8.5mm bits for metal are available in HSS, titanium, tungstun, cobalt, carbide and many other variations.

HSS metal drill bits would be considered ‘budget’ drill bits and are ideal for drilling softer metals. However these will not drill harder metals effectively.

Carbide drill bits would be at the top end of drill bits and will be expensive. They are best suited for specialist drilling applications and are often used in production.

Cobalt drill bits are reasonably prices and are capable of drilling harder metals. They will also resist heat build up better than many other drill bits. For these reasons cobalt drill bits are generally the preferred option for mechanics, diy enthusiasts and other professional installers.


A conventional 8.5mm cobalt drill bit for drilling metals will have an overall length of 117mm

Longer drill bits can be bought from specialist suppliers

8.5mm drill bit with dimensions - 8.5mm drill bit

Which 8.5mm drill bit should you buy?

Drill bit set with customer - 8.5mm drill bit

When buying any drill bit for drilling metal it is important to buy one which has a number of excellent cutomer reviews.

customer reviews icon - 8.5mm drill bit

Ideally the manufacturer should be able to show a testing certificate indicating the hardness of the drill bit. And of course a supplier which offers a 100% money back guarantee is likely to be supplying a quality drill bit.

SGS tested - 8.5mm drill bit

Drilling metal – what speed?

When drilling metal with any drill bit it is important to drill at the correct speed. Drilling at too high a speed will cause the drill bit to overheat. It can also cause a metal to ‘work harden’ so it is advisable to drill slower rather than faster.

The below drilling speed chart will tell you the correct speed to drill at. This will depend on the metal you are drilling through plus the size of the drill bit you are using.

Do not worry if you are unable gauge the exact speed of your drill. The most important thing is not to drill too fast. So if you have an adjustable speed drill then start off slow.

The main object is to avoid overheating your 8.5mm drill bit. So apart from drilling slow you should take breaks and use a drilling lubricant.

Metric speed and feed sheet e1537795412627 - 8.5mm drill bit

Top Tip For Drilling Metal

If you are drilling any metal it is important to use a metal lubricant. This is especially important when using a larger bit like an 8.5mm drill bit. Larger drill bits will generate heat more quickly thank smaller ones. So apart from drilling slowly and using reduced pressure it is very important to use a lubricant.

                                                       CUT IT drilling paste on end of drill bit 300x275 - 8.5mm drill bit

A good quality lubricant will contain High Pressure Additives. This will reduce the friction whilst drilling and assist in controling the temperature. Ultimately increasing the life of your 8.5mm drill bit.

8.5mm drill bit to inches

An 8.5mm drill bit is approximately 0.334646 inches

Conversion chart for drill bit sizes 1 - 8.5mm drill bit

Video tutorial / tips on drilling harder metals

How to drill holes in thick metal icon 300x148 - 8.5mm drill bit


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