Counterbore

When a bolt head or nut needs to be recessed, because it cannot protrude from the work surface, or you want to bung the hole over the fastening, then this counterbore is the tool for the job. After the hole for the bolt or screw has been drilled, this counterbore is used to cut a larger hole around the first one. The counterbore shaft must be the same diameter as the bit used to drill the original hole, as it will guide the cutter to make a perfectly centered round recess. To find precisely-sized bits to match the bore guide shaft, have a look at our auger bit page! As with the auger bits, the counterbore requires a powerful drill to cut the relatively large diameter hole. This will make for a quick, clean and easy job.

Counterbore from Star-M
The counterbore from Star-M in Japan features carbide-tipped cutters for a long working life. These are very useful tools in large carpentry applications like building sheds, carports and timber framing jobs. All of the tools have a hexagonal 9mm shaft.
Recommended Revolutions per Minute (RPMs): 1000 - 1500 ^-1
Guide Shaft Length 70 mm
Shaft Length 40 mm
Total Length 150 mm
Enlarged Photo from Guide Shaft end
Enlarged Photo from Shaft end

Drawing middle left:

Carbide-tipped nicker or first cutter
Carbide-tipped main cutter
Hex key nut to fix the cutter to shaft
Counter nut to stabilize fixation
Carbide-tipped nicker or first cutter
Carbide-tipped main cutter

Guide-shaft- Diameter	Cutter- Diameter	Order nr.	Price
12 mm	30 mm	312660	^✱€ 72.90
12 mm	40 mm	312661	^✱€ 83.90
15 mm	30 mm	312663	^✱€ 72.90
15 mm	40 mm	312664	^✱€ 83.90