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High-speed steel drill bits are probably the first
drill bit bought by most DIY’ers. This is because they can be used to
drill into most metal and wood surfaces. We show you how to use them to
drill into steel.
View
our Drill size table. To demonstrate how to drill into a mild
steel surface we chose a small diameter and larger diameter highspeed
steel (HSS) drill bit as well as a semiprofessional,
variable-speed/reversible impact drill with a keyless chuck.
Steel has a uniform texture and characteristic
tensile strength. This means that there is no unevenness in the surface,
which makes the drilling operation a lot simpler. Start by securing the
steel surface. This is the most important safety aspect of this drilling
operation, as it will prevent the steel from revolving at a dangerously
high speed, if it suddenly catches in the drill.
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| Use
a hammer and centre punch to drill the hole. This will keep the drill
bit from slipping when you start the initial hole. If you want to drill
a clearance hole that is larger than 8mm in diameter, it is advisable to
first drill a pilot hole of 3-5mm. Open the double-sleeve keyless chuck
by twisting it from left to right, install a small diameter high-speed
steel (HSS) drill bit and then close the chuck by twisting it from right
to left. HSS twist drills have a flat (dead) spot in the centre of the
bit, which only serves to hinder the drilling process by causing heat
and friction, if you don’t drill a pilot hole first. |
| Titanium
bits
If you are looking for
a drill bit that is more advanced than standard HSS, why not try
an HSS titanium coated drill bit? This drill bit is manufactured
from high quality molybdenum tool steel with an external coating
of Titanium Nitride, which makes the drill bit surface extremely
hard. Titanium coated drill bit bits offer all the advantages of
normal HSS drill bits. However, the TIN coating, which has a
distinctive solid gold appearance give these bits some extra
advantages. These include increased cutting speeds, which save
you time and an extended tool life of five times that of a
normal HSS drill bit, making this drill bit good value for
money. A titanium coated drill bit also gives a superior hole
finish, making your DIY work look professional.
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| Mark
the steel surface with a hammer and centre punch |
Use
a small diameter HSS drill bit to drill a pilot hole. |
Follow
up with a larger diameter HSS drill bit. |
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| Tips:
When
you are drilling with 4mm and smaller diameter drill bits, don’t apply
too much pressure to the drill or its side handle, otherwise the bit
will snap or break. Also bear in mind that if the angle at which you
exert the pressure is not 100% perpendicular to the surface, the bit
could very easily snap or break.
Never
use your drill in wet or damp conditions, as moisture readily conducts
electricity.
You
can improve a HSS bit’s efficiency and reduce the amount of effort
needed to perform the drilling operation by changing and sharpening the
bit, if the tip shows wear or when the machine’s speed slows down.
Using lubricants will also help to improve the results of your drilling
operations. Light oils or grease is recommended for hard metals, whilst
water is suitable for soft metals and thermoplastics.
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It
is therefore advisable to start a pilot hole on the mark made by the
centre punch and drill it all the way through the steel surface, before
withdrawing the bit. Now insert and secure a larger diameter HSS drill
bit into the keyless chuck. Remember to lower the drill’s speed
setting, as you are using a larger diameter drill bit. Once you have
done this, position the tip of the bit on the pilot hole and begin
drilling. You will notice that drilling through the pilot hole provides
the larger diameter bit with guidance and thus prevents it from
wandering on the steel surface. bits, HHS bits and HSS.
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