If you are using an angle grinder on difficult, sticky floors and it is slowing down so much that you smell the motor burning do not stop the grinder or it will burn out! The motors are very powerful, but they generate a lot of heat. They have a strong fan inside that sucks air in around the back handle and blows it out the front of the grinder to keep the motor cool.
Do this instead:
If it smells like it is too hot, immediately lift the grinder off the floor or move it to an area 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 20 seconds. Angle grinders are OK used to their capacity which naturally slows them down a bit, but tries not to slow them too much.
What slowing the grinder does:
On very sticky materials the friction from the disc melting the product 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 and it slows down the fan that is meant to keep them cool.
The result – a double whammy of heat! … but still some cooling.
Stopping the grinder at that time removes all cooling so that the temperature rises and ruins the motor wiring. The result – new grinder.
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 stop the slowdown:
If it is a more frequent occurrence there may be a better way to tackle it which is with a PCD scraper disc fitted to the angle grinder instead of the diamond grinding cupwheel. The coating or glue is scraped away instead of being ground. They can be very fast and will tackle coatings of 500 to 10,000 microns thick.
Maintenance of your angle grinder:
Some periodic maintenance is required 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.
There are only two things to keep an eye on:
First is the brushes. They wear very slowly, even in a concrete dust environment and you can check them by first disconnecting the power.
Next remove the small panel at each side of the grinder near the trigger-switch handle and remove the carbon brushes that are connected to a spring. Check your grinder manual for more information.
The second thing to check is wear of the front bearing. They both seem to wear at about the same time 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.
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.
Author – Peter O’Shannessy (Concrete Grinder Sales)
* The above information is to be used as a guide only and Con-Treat accepts no responsibility for any consequence resulting from the advice contained herein or verbally.