Quick Answer

Grinding problems are usually tooling or technique issues rather than defects in the concrete. Rake marks (also called chatter lines or washboard streaks) are caused by the grinder bouncing or skipping across the floor, in most cases from worn bearings, a too-aggressive bond, incorrect pressure, or a warped plate. Fix the equipment, soften the bond, and abrade flatter and slower.

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What Causes Rakes

What you should know before starting.

Fresh, sharp metal-bond discs like our double-S segment discs cut smoothly; old, glazed discs chatter.

• Too much downward pressure: the plate digs in and bounces.
• Worn tooling: segments that are half gone no longer cut consistently.
• Uneven subfloor: over a slab joint or hump, the plate rocks.
• Too hard a bond: the diamonds cannot protrude, the tool skips instead of sawing.
• Worn bearings or drive belt: the head wobbles and chatters.

Contractors who skip this stage usually end up redoing the floor.

A Practical Guide to Remove Rakes

The key points in practice.

• Reduce downward pressure. Let the weight of the equipment do the work.
• Slow the feed. Overlap passes by 30%.
• Take one coarser pass across the rakes, then resume normal sequence.
• Inspect the equipment: bearings, drive belts, plate flatness.
• Switch to a softer bond. Hard concrete requires a softer bond.

This is where most crews get it right - or lose time.

Prevent Them: Step-by-Step

A closer look at the details.

Browse the full range in our concrete abrading discs category.

• Use matched sets of tools; never mix worn and new discs on the same turret.
• A reliable habit is to start with a level, clean plate.
• Inspect the plate for warping after dropping the grinder.
• Diamond abrade rather than speed abrade: slower feed gives a flatter outcome.

Getting this part right saves a full re-pass later.

Frequently Asked Questions

Q: Will I a finer grit remove rake marks?

A: The practical answer is, Sometimes, if they are shallow. Deep rakes require a coarser pass first. Trying to burnish them out in most cases wastes a pad set.

Q: Is rakes caused by the floor or the machine?

A: For most jobs, Mostly the equipment or tooling. A well-tuned grinder on good tooling should not leave rakes.

Q: Is it necessary to need to re-grind the whole floor?

A: In short, In most cases a single coarser pass across the affected area, then stage back through the grit stage sequence.

Looking for the right tool? Check our 3'' Metal Bond Diamond Grinding Disc with 10 Segments. Looking for the right tool? Check our 3'' Metal Bond Diamond Grinding Disc with 5 Segments.

Conclusion

The fix is usually straightforward once the bond and machine are matched to the slab. Rakes are a tooling or equipment issue, not a concrete issue.