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Nitto One-touch type.
Realize high-speed and high-precision drilling with a minimal force.


  • Nitto One-touch type.
  • Circumferential cutting, in which cutting area is very small, permits boring large holes with low-powered machines.
  • No need of pilot holes for positioning by using center pin. An inner spring provides easy removal of chips.


  • For drilling in steel, shape steel, stainless steel, and cast iron up to 35mm (MB350A) or 50mm (MB500A) in thickness.
  • Best for drilling work in shipbuilding, bridge building, framework building, and steel structure building.


Cutter size: 350A: o14mm to 40mm --- (Max. drilling depth: 35mm)
500A: o18mm to 65mm --- (Max. drilling depth: 50mm)
Number of tips: Cutters of o14mm to 39mm --- 6pcs.
Cutters of o40mm to 64mm --- 8pcs.
Cutter of o65mm --- 10pcs.
Tip width: Cutter of o 14mm --- 3.2mm
Cutter of o 14.5mm --- 3.4mm
Cutter of o 15mm --- 3.7mm
Cutters of o 16mm or larger --- 3.9mm
Overall length: 350A: 72mm
500A: 91mm
Shank size: 19.05mm
Applicable electric drill: Magnetic drill presses, upright drilling machines, radial drilling machines, lathes, and milling machines
* Click here for the guideline for cutting conditions of METAL-BORER.