I
T FEELS LIKE EVERYONE I know has an angle-grinder horror story to
share. Most of the time it’s a ‘friend of a friend’ story, but that doesn’t make
them any less terrifying. While I’ve had a few close calls myself, these days
I seldom get the skriks when using a grinder. Part of this has to do with practice
as well as exposure to the tool, but mostly, it’s that I no longer fear them.
As I stated in the grinder comparison article in the March/April issue, in
my experience most angle-grinder accidents happen when the operator isn’t
confident in what they’re doing. Of course, that doesn’t help first-time angle-
grinder users, as it often takes time to get comfortable with the power tool.
If you’re new to angle-grinder operation, here are a few tips as to why things
typically go wrong, and how to prevent them.
THE RIGHT DISC FOR THE JOB
Here’s how a common scenario often plays out: You’re using an angle grinder
to cut a piece of steel with a dedicated cutting disc that’s much thinner than
a regular grinding disc. Once the steel is cut, you choose to de-burr the edges
by grinding them smooth.
But, instead of taking the time to swap the cutting disc for a thicker grinding
disc, you think to yourself: ‘Ag, it’s just a couple of edges. I’ll just use the cutting
disc and press down gently.’
I’ve seen this happen many times while working as a fitter and turner.
The problem is that cutting discs aren’t designed to endure lateral forces, and
when you use the face of the disc in this way, the disc not only gets dangerously
thin, it also flexes to a point where it inevitably shatters, while rotating at an
incredibly high speed.
It’s also vitally important that you read the information sticker on the disc,
to make sure you’re using the right disc for the material you’re working with.
Lastly, most general-purpose angle grinders have a maximum-disc diameter
that must be adhered to. Exceeding this specification may not only push the
grinder beyond its abilities, but the disc itself may not
be able to handle the high revolutions.
KICKBACK
‘Kickback’ is arguably the thing that most people
fear when they think of operating an angle grinder.
This is when the disc ‘bites’ into whatever you’re
cutting, then violently and unexpectedly jumps
backwards. Making sure the cutting disc is upright
and perpendicular while using the machine is the
first step towards mitigating kickback.
You also want to be sure the item you’re cutting is
either clamped in a vice, or securely supported on either
side of the cutting area. For example, if you’re cutting
a sheet of corrugated roofing or ceiling board, make
sure the sheet or board is supported in the middle, so
it doesn’t collapse inwards and pinch the disc.
When it comes to disc placement, you want to use
the 8 or 9 o’clock positions on the disc’s circumference
when cutting most materials – where 12 o’clock is
considered the top of the grinder. Importantly, if you
lower the angle-grinder’s body below the cutting height,
the grinder’s own weight helps to control any kickback
or radial movement.
In short, if the disc does happen to bite, you want
the grinder to ‘kick’ away from your body, and not
backwards towards you. With that in mind, it’s always
good practice to offset yourself to the side of the angle
grinder’s line of operation.
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PRACTICAL KNOWLEDGE
76 MAY / JUNE 2022 popularmechanics.co.za
GRINDER SAFETY
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