National Flooring Equipment

In the work?

Check out our resources for professional contractors

Add to Wishlist



The 8274-4 is the only grinder on the market offering 3 HP at 115 volts while operating at a 230-volt level. With variable speed and a soft start to control its amperage draw, the 8274-4 adjusts to the needs of small or large jobs. The versatility of the 8274-4 is derived from its quick-change magnetic tooling to remove thin-set, coatings, adhesives, and high spots, prepare concrete and overlays for coatings, and sand and refinish wood flooring. Polishes floors to a high-gloss shine.

Close Form

Request Quote for


Use Wufoo templates to make your own HTML forms.
  • Three-part adjustable angle handle
  • Choose from 15A or 20A circuit-breaker settings with a convenient switch on the side of the controller; the 15A selection limits motor draw to 15 amps; the 20A selection pulls up to 20 amps
  • Forward and reverse directional controls increase tooling productivity with cleaner consumables and more even wear
  • Variable speed control
  • Dual rear vacuum ports
  • Flip-style weights for added or decreased head pressure
  • Removable handle and weights for easy transport
  • 18-inch grinding path; uses National’s patented self-tensioning, single-belt design to prepare concrete surfaces to a 3000-resin shine
  • Adjustable velcro dust guard lets the machine operate within an eighth of an inch of walls and promotes nearly dustless operation
  • Grinder head rotates 90 degrees for easy tooling change access; Morflex couplers, polishing undulating concrete surfaces or creating a uniform scratch pattern for coating applications; operates a complete dry grind and polish system to eliminate messy and hazardous slurry
  • Modular design allows you to pull the machine into three different parts for transportation

Width20"51 cm
Disk Size18.5"47 cm
Max. Height52"132 cm
Min. Height27.5"70 cm
Max. Length75"191 cm
Min. Length38.5"98 cm
Weight388 lb176 kg
Drum RPM133.8
Motor RPM1740
Frequency60 Hz
Motor PhaseThree*
HP32.24 kW
Amps15 or 20-controller can switch between both settings
*Conversion from three-phase to single-phase power
  • 401882: Morflex couplers
  • 9241 Quick-change magnetic-mount assembly: Three assemblies and three 73250 tooling holder mounting screens are required
  • 9245 Velcro adapter: Mounts onto the 9241 quick-change magnetic assembly for using polishing pads and brazed disks. Three adapters are required.
  • 6280-401B: 7/32 t-handle wrench
  • Instruction manual

National recommends adding these accessories to your order, so you can stay in the work longer.

DL2000 Dust Collector
9507-16: 16 Grit Half Bar Metal Bond Diamond Insert (6 min. suggested)
9507-30: 30 Grit Half Bar Metal BondDiamond Insert (6 min. suggested)
9521: Carbide Tooling Holder (6 min. suggested)
9554: 1Up PCD- 1/2 Round (6 min. suggested)