(180mm) angle grinders
Nine inch angle
grinders are mostly used for heavy duty
concrete floor grinding and are often
used beyond their normal limits when the
work is slow and difficult.
If your angle
grinder smells like
it is too hot, immediately lift the
grinder off the floor or move it to an
area on the floor that you have already
ground where it can spin freely again
which will allow the fan to pass cool
air through the grinder and cool it
down. This will only take about 10- 20
seconds.
Angle grinders are
usually fine to use to their capacity which
naturally slows
them down a bit, but try not to slow them too much
for too long.
Slowing the grinder
dramatically increases heat
- here is why:
When an angle
grinder is used to remove sticky
materials the friction from the diamond
grinding wheel on the floor can
cause the grinder to work so hard that
it slows down to half its speed.
The extra load
pulls more current through the windings
and causes them to heat up while at the
same time it slows
down the fan that is meant to keep them
cool.
This
causes a dramatic rise in heat through
the windings and
stopping the
grinder at this time will remove all cooling
and result
in grinder burnout.
Grinders can take a lot of punishment
Experience has
shown that grinders can get very hot
many times without problems if they are
cooled again quickly in the manner
described above.
But why work on the edge of disaster?
If the grinder is slowing down strongly
on sticky material just take smaller
bites into the coating.
No other grinder
using the same power source will do it
faster so it is just going to take
longer and that type of grinding
situation is not very common, it only
happens to some contractors very
occasionally.
PCD
Scraper Discs can also help
If sticky
coatings is a more
frequent occurrence there may be a
better way to tackle it which is by
using a PCD scraper disc fitted to the angle
grinder instead of the diamond grinding
cupwheel.
The coating or glue is
scraped away with polycrystalline
diamond teeth on these special cupwheels.
They can be very fast and will tackle
coatings of 500 to 10,000 microns thick
(0.5mm to 10mm) or (1/32 inch to 1/2
inch).
Maintenance of your angle grinder
Some periodic
maintenance is require although you will
be surprised at just how long it can
keep working without any.
The difficult part
is explaining how long it will take to
wear.
A guess would be
maintenance once per year when it is
used three or four times a
week for 2 hrs each time.
Brushes
First is the
brushes which wear very slowly, even in
a concrete dust environment and you can
check them by first disconnecting the
power and then removing the
small panel at each side of the grinder
near the trigger-switch handle and
take out the carbon brushes that are
connected to a spring.
Check your grinder manual for more
information.
Front bearing
This seems to wear at about the same
time as the brushes so if you replace one, also do the
other.
To check bearing
wear, disconnect the power, turn the
grinder over and try to wobble the
diamond disc on the shaft. There is no
wobble on a new grinder.
If you can feel a
definite wobble take it to a power tool
shop and have the bearing replaced. If
you let it go for too long the gears
will wear and it may not be economical
to repair the grinder.
Many contractors
figure that if it has done that much
work without any trouble it may be
better to just replace the whole grinder
- they are very low cost compared to the
amazing amount of work they do.
Next
page
"Grinding
Hard Concrete"
