The decorative column this month is written about angle grinders. When I talked to contractors about what they thought was important, there were a lot of different answers. One contractor told me that he tends to buy tools for a project, not expecting them to last much longer than that. So he doesn't want to pay for the highest quality. His tools represent a way to get the job done and then move on to the next one.
Some contractors complain about their labor force. They buy good equipment and want it to last but their labor in the field doesn't take care of the equipment and the life expectancy turns out to be low. But even with the best labor force, most tools on jobsites probably don't get cleaned or maintained very much—especially electric power tools. I've seen workers on jobsites set power tools down in the mud. And if you set two tools side by side, one new and one used, workers will choose to work with the new tool.
Perhaps smaller companies take better care of their tools than the larger more impersonal ones. The investment is probably harder to make.
There are also people who love using tools and are proud owners. They do everything right: keeping them clean and maintained, and using them properly. For them it's also fun keeping up-to-date with the latest advances in the industry. I am one of those people.
Decorative concrete contractors probably use 4½-inch angle grinders more than any other electric power tool. It gets used for touch up work on slabs to improve the quality of the appearance of stamped concrete, to engrave pattern lines, to diamond polish small areas such as countertops or their vertical edges, to grind or polish restricted areas that can't be reached by larger tools, or sometimes even to grind steel or cut rebar. If you mount a sanding disc on them, you can sand concrete surfaces as well.
A typical grinder runs between 7000 to 10,000 rpm—most being in the 10,000 rpm category. A few models have variable speed controls that allow you to set speeds between 2000 to 10,000 rpm. They are especially good for diamond polishing where lower rpm and controlling speed is important.
The most desirable features
Regardless of personal preferences, the grinder you select should include these basic features.
- Ergonomics are important. The tool you choose must feel comfortable in your hand. This usually means that the barrel of the grinder should have a small enough diameter that you can get your hand around it. The switch should be located in an easily accessible place.
- The protective shroud around grinder bits should be easy to rotate and adjust.
- Grinders must have a good line-of-sight in both the vertical and horizontal axes.
- Cement dust is very hard on bearings and brushes. The engineering of the tool should minimize the amount of dust that flows through the tool, especially around the armature, brushes, the switch mechanism, and bearings of the motor.
- Brushes should be easy to change. Many companies arrange things so that you don't have to remove the housing of the motor to change the brushes.