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Understanding metal cutting drill bits

Mar 23, 2016

Whilst it may be just another part of a day's job for professional tradespeople, cutting or drilling through metal is not the sort of every day activity most home handy people perform. This article is written more for those carrying out home repair activities.

HSSS what?

HSSS =High Speed, [straight shank] and it is the first two words that cause some inexperienced home maintenance people most bother. An HSS drill bit is made for modern high speed power drills and is designed to withstand heat. It is useful for drilling through most materials, excluding concrete and masonry [link to concrete bits] and is often thought of as an all purpose metal boring tool, However some caution does need to be exercised in selecting the correct metal cutting bit.
Drill bits for cutting through metal are generally at the high end of the price scale, so before you rush out and buy one, lets look at what each type can do.

For simplicity we can look at 3 basic types of metal bits.

We have already talked about HSS bits, these are designed to stay sharp and resist heat [the enemy of all drill bits] and are ideal for most general purpose work including, leather, plastic, wood and softer alloys or metals, such as aluminium. They are also the most economically priced. Basic HSS bits can also be resharpened.

You may also see HSS bits that are black, coated with a black oxide, which does help make them last longer but generally have the same cutting range as basic HSS bits.

Either of these bits is probably going to serve the needs of most average amateur home renovators.
However from time to time you may need to tackle a job where you need to bore a hole in a harder metal, such as steel or, usually for the handy person, stainless steel, so you need a heavy duty bit specially designed for cutting metal. We have two choices: COBALT or TITANIUM.

Both Cobalt and Titanium drills are extremely hard, dissipate heat quickly and are resistant to wear. Consequently they stay sharp longer, meaning they last longer. If you know you are going to be drilling through a lot of heavy or hard metals, either of these metal cutting drill bits would be a good investment long term. Titanium drill bits are coated [with titanium oxide] making them harder and therefore longer lasting than cobalt, However a titanium metal drill bit can NOT be resharpened whereas a cobalt bit can.

Of course, at the end of the day it is how you use and treat your metal cutting drill bit that will determine its life span and effectiveness. They may be tough and hard and resistant to heat but that doesn't mean you can use them till they glow red.
As always with any bit, a good quality metal cutting drill bit needs a good quality drill with [link to electric drills] enough power to support the bit. Cutting corners at this level is not just a waste of money but also an accident waiting to happen.
So, essentially, the HSS bits that came with your drill set will probably do most of the jobs the hone renovator is likely to encounter, but for heavier work with steel or iron then a titanium or cobalt metal cutting bit is needed.

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Next: How to choose the best drill bit for metal

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