Uneven cutting or scalping is usually caused by a cut height set too low for the terrain, dull or damaged blades, an uneven or bumpy lawn surface, or wheels and a cutting deck that cannot hold a steady height on slopes and dips.
Common reasons the cut looks uneven
- Cut height too low. A low setting scalps high spots, mounds, and slope crests where the deck momentarily drops closer to the soil.
- Worn or damaged blades. Dull, bent, or chipped blades tear rather than slice, leaving ragged, patchy results even at a correct height.
- Uneven ground. Ruts, molehills, tree roots, and settling create high points the mower shaves and low points it misses.
- Traction and tilt on slopes. Slipping wheels or a mower that leans on inclines changes the effective cut height across a pass.
- Coverage gaps. Random or grid patterns that do not fully overlap can leave uncut strips that read as uneven growth.
- Wet or overgrown grass. Damp clippings clump and mat, and very long grass bends away from the blades, both of which distort the finish.
Step-by-step fixes
- Raise the cut height first. Set a higher height and lower it gradually over several sessions. This alone resolves most scalping on bumpy or sloped lawns.
- Inspect and replace the blades. Check for dull edges, bends, and cracks. Most robot mowers use small replaceable blades that are inexpensive and meant to be changed on a regular cycle.
- Level the worst spots. Fill ruts and low areas and knock down mounds so the deck is not forced up and down within a single pass.
- Clean under the deck. Remove caked grass from the blade disc and housing, since buildup unbalances the cut and adds drag.
- Adjust scheduling for growth. Mow more frequently in peak season and avoid wet conditions so the mower removes a little at a time instead of long, bending grass.
- Check slope handling. Confirm the lawn is within the mower’s rated incline. Clean the wheels and, if traction is poor, review any documented slope limits for your model.
When it is the mower, not the lawn
If the height is raised, the blades are fresh, and the ground is reasonably level but the cut is still uneven, the hardware may be at fault. Warning signs include a blade disc that wobbles or sits visibly off-center, a cutting motor that changes speed or cuts out under light load, a mower that consistently pulls to one side on flat ground, or a wheel that slips even when clean and dry. Vibration or a scraping sound from the deck also points to a bearing or mounting problem rather than a lawn issue.
These mechanical faults are the kind that manufacturers sometimes address through service updates, so it helps to track them by model on the Tracker, and to weigh cut consistency alongside the broader question of robot mower autonomy.