Get the best results from the machine with these basic how-tos.
Need to do some aggressive surface prep? A concrete scarifier, aka concrete planer, is the machine to use if you need to shave off a lot of material. Scarifiers are well suited to leveling concrete and asphalt, removing trip hazards on sidewalks, creating sidewalk grooves and removing heavy-duty overlays and hard industrial coatings.
To get the most from the machine, follow these tips.
Practice operating the machine before you start working. Learn how to set the depth control and how to disengage and engage the drum.
“There’s a little bit of a learning curve, and you have to take a lot of variables into account,” said Tony Calcopietro, national account manager for EDCO, which manufacturers equipment designed for the rental market. “But once you understand the material that you’re trying to shave or plane and how it’s reacting to the machine that you have, you can complete your job.”
Set the right drum depth
The project should dictate the drum depth. For example, said Calcopietro, “if you have a thermoplastic line on an asphalt surface, you can drop the depth of the drum to maybe 1/32nd of an inch so it’s just skimming along the top.” On the other hand, “with an industrial application, where you have one-eighth inch or one-quarter inch of epoxy, you really need to plunge that drum into the surface.”
Be aware that setting the drum too low could cause the scarifier to bounce across the surface rather than plane it.
Before starting the scarifier, make sure the engage/disengage lever is in the disengage position. You don’t want the cutter touching the surface at startup.
Make multiple passes if necessary
If you need to remove more than one-eighth inch of material, don’t strain the machine by trying to do it in one pass. “The engine would labor, the belts would burn out and the carbide cutters would be damaged,” said Calcopietro. “The worst-case scenario is the carbide cutters, spacers and shafts break loose causing a workspace hazard.”
Instead, use step cutting. For example, if you need to remove one-quarter inch of material, take two one-eighth-inch passes. It’s best to go north and south on the first pass and then east to west on the second. That allows for the material to be evenly removed to depth while allowing for any height differences in the surface.
Move at the right pace and in the right direction
If you push the machine too fast, it won’t cut as deep as you want; it will skim over the top of the surface. Move at a pace that allows the machine to cut the material. The size, weight and horsepower of the machine and the hardness of the material will dictate the speed, said Calcopietro. If you’re using a self-propelled scarifier, make sure you hold onto it so it doesn’t walk away. Never stop while the cutter is engaged.
If you’re planing down a trip hazard, move the scarifier from the higher side of the concrete to the lower side.
Pay attention to the spacing and pattern of the cutting assembly
The cutting flails should move freely on the shaft of the drums. If they’re tight, try removing a spacer. Always insert at least one spacer between a flail and the edge of the drum.
Adjust the spacing and the patterns of flails on the shaft to achieve different surface textures. The less spacing between flails, the smoother the finish.
Machine maintenance counts
Follow the directions in the manual for lubricating the machine, checking the belts, changing out shafts, etc. Keeping the machine in top condition will help ensure you get the production levels you want.
Finish up with a grinder if necessary
Remember that scarifiers leave a rough surface. If you plan to coat the surface, you may want to use a concrete grinder after you finish with the scarifier to smooth the surface before coating it.
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.