Average response time: under 24 hours
Grind edges with a dedicated walk-behind edger fitted with a diamond cup wheel for the first 100 to 200 mm from the wall, then finish the last 20 mm by hand with a handheld angle grinder. Set the edger to the same grit as the main plate, overlap the main grind by 30 mm, and keep the cup wheel flat to avoid scalloping. Plan for one hour of edge work per 10 meters of wall, and always run a dust shroud on the handheld tool because edge work is where silica exposure peaks.
The big planetary grinder cannot reach within 150 to 300 mm of a wall, column, or pipe penetration, so that band is always left to edgers and hand tools. It is also the area crews skim fastest, which is why most finished floors show a darker, rougher strip along the base of the wall. Doing edges properly means matching the main plate's scratch pattern exactly, so the final polished surface reads as one continuous plane and the wall line does not stand out under stain or epoxy.
For the bulk edge band, a walk-behind edger with a 250 mm cup wheel such as the JOY-CW-R6 six-round-segment cup covers 200 mm in a single pass and matches the scratch depth of a 30/40 trapezoid plate. Choose the same grit family as the main machine so transition passes blend cleanly, because mixing grit families leaves a visible band along the wall that no amount of polishing will hide.
Set the wheel so the cup hangs 100 mm beyond the housing, which lets you grind tight to the wall without the shroud scraping the baseboard. Keep the wheel parallel to the floor; tilting it digs a crescent and leaves a line you will see through stain. Run the edger at 1,500 to 2,500 rpm, walking at a steady pace, and make two passes in opposite directions to keep the scratch pattern flat.
For the last 20 to 30 mm that the edger cannot reach, use a 115 or 125 mm angle grinder with a small cup wheel and a dust shroud. Do not use a 180 mm wheel in corners; it is too heavy and too aggressive. Work in short, overlapping arcs and keep the wheel moving, because holding it still melts the bond and gouges the slab, leaving a pit that later passes cannot fill.
Internal corners and column bases need a smaller approach. Use a 50 mm diamond hand pad or a triangular cup wheel for the last 50 mm, because full-size cup wheels always leave a rounded arc you can see after staining. Work from both sides of the column toward the center so the scratch pattern meets smoothly, and spend the extra five minutes here rather than touching it up after the main floor is done.
The cup wheel throws sparks and grit sideways, so protect baseboards, electrical outlets, and painted walls with masking film or a strip of hardboard held by magnets. Never let the edge of the cup touch the wall: it will gouge the concrete corner and leave a notch that later grinding cannot hide. On drywall or painted masonry, run a plastic shield between the wheel and the surface, and check the wall after every few passes because masking tape can let go as the grit heats it.
Internal corners are where hand edgers struggle. Use a small triangular diamond cup or a 50 mm diamond hand pad on a sanding block for the last 50 mm, because cup wheels always leave a round arc. Around pipe penetrations, split the area into arcs and blend from both sides. Double-row cup wheels like the JOY-CW-DR double-row cup are a good middle ground: aggressive enough to cut fast, stable enough to run close to vertical surfaces without catching, and wide enough to cover 200 mm in a single pass.
Edge work generates more respirable dust per square meter than center-floor grinding because the hand tool has poor shroud coverage. Always connect a HEPA extractor to the shroud, wear a P100 respirator, and wet-wipe walls after the job to catch settled dust. Do not blow dust off with compressed air; it just resuspends into the air the crew is breathing, and it settles right back on the floor you just cleaned. Treat the edge strip as the highest-exposure zone, and do not let anyone work the hand grinder without a shrouded vacuum, even for five minutes.
After the main floor is ground, run one pass of the next grit along the edges with the edger so the scratch depth matches. The goal is that when you stain or polish, the wall band reads the same tone as the rest of the slab. For a full set of edge and center-floor tooling, browse the concrete grinding catalog and pick cup wheels and trapezoid plates in matching grit pairs so the edge band never lags behind the center grind.
Written and reviewed by JOY TECH - an SGS & BV audited, CE/RoHS certified diamond tools manufacturer founded in 2004, exporting to 50+ countries.
Our factory and quality management system are audited by SGS and Bureau Veritas. Products meet CE/RoHS requirements and every piece is 100% inspected before packing.
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