Choose the right accessories, plan your path and use good technique to get the best results.
Ready to remove a scuffed surface coat from a concrete floor or get rid of the glue left by carpet padding? A concrete grinder can help you get the job done in a relatively short time. Follow these tips to make the most of the machine.
Before you start
Before you start your project, set yourself up for success.
- Choose the right cutting tool. Carbide stripping accessories work great for topical concrete floor cleaning and scraping jobs. Diamond accessories can handle both light and heavy-duty jobs. Use diamonds with lower grits when aggressive grinding is required, and higher grits for general-purpose grinding jobs and polishing. PCDs, or Polycrystalline Diamonds, are used for very aggressive applications such as industrial coating removal.
- Choose the right bond. Softer bonds are good for less abrasive surfaces, like concrete made with river rock. Harder bonds are ideal for concretes with high sand content. Not sure what you’re working with? Start with a medium bond.
- Do a level check. For the best results, check the level of the grinder discs before you start working. The goal is to have 100 percent accessory surface contact. Hold the machine in place for several seconds, then notice the pattern it leaves. You should see a full circle ground into the surface. If you see a half-circle, follow the directions for adjusting the level of your grinder. If you’re working over a large area, perform the level test periodically and adjust the grinder level as necessary.
- Plan your path. Electric cords can get in the way when you’re grinding. So can the hoses and canisters of a dust collection system. Plan your path to make sure you stay connected without getting tangled up.
- Spread sand on the slab if you’re removing tacky tile glue or other adhesives. That will ball up the material to make it easier to remove.
- Don PPE. Wear safety glasses or goggles, and add a face shield if there’s a lot of debris flying around. Safety boots and gloves are also smart. Depending on how much dust the job is raising, you may need respiratory protection as well.
Use good technique
Take your time and allow the machine to do its work. If you move too fast, odds are you’ll end up redoing some areas. The way you move the grinder depends on the type you’re using.
- Swing the machine from side to side if you’re grinding with a single disc or a dual disc rotary grinder.
- Walk forward and backward, like you would with a lawnmower, if you’re using a planetary grinder.
Keep it operating efficiently
- If your diamonds begin to glaze and become ineffective when you’re working on a hard, dry surface, use silica sand as a secondary abrasive to keep them sharp.
- Consider adding weight to your dual-disc grinder if the grinding process is taking too long. The more weight you have, the more aggressive the grinder will be. But don’t go overboard; adding too much weight can bog down the motor and damage the machine.
- Watch the belt tension. Unusual noise, high machine temperature and premature belt and pulley wear can be indications that the belt tension needs adjusting.
- Grease the bearings and perform other maintenance as outlined in the manual. (If you’ve rented the machine from a reputable equipment provider, it should be ready to go.)
If you have questions about which accessories or PPE to use or need help choosing a concrete grinder to rent, visit your local United Rentals branch or call 833-398-8233.
Freelance writer Mary Lou Jay writes about business and technical developments in a variety of industries. She has been covering residential and commercial construction for more than 25 years.