Sutton 1mm Heavy Duty Cobalt Jobber Drill Bit - Cobalt

The Sutton D109 Heavy Duty Cobalt is a jobber drill in cobalt high speed steel (HSS-Co) with a colour-temp finish. It has 25° right-hand helix flutes (R25), a 135° point (Form C self-centring split point on larger sizes), and is made to DIN 338.

Heavy-duty design; cobalt content for high abrasion resistance; suitable for hard materials up to 850 N/mm²; self-centring 135° split point.

This is the metric and fractional-inch range: 151 sizes from 1 to 13 mm, with flute lengths of 12 to 111 mm and overall lengths of 34 to 151 mm. 30 of the sizes are fractional-inch drills, shown with the inch size first (for example 21/64 in = 8.33 mm); the rest are metric sizes. Pack quantities by size: 1 mm to 7.5 mm: pack of 10; 7.54 mm and over: pack of 5.

Where this product is used

• Hard materials up to 850 N/mm², the range this heavy-duty cobalt drill is made for, with a self-centring 135° split point.
• Machine drilling on a drill press, mill or lathe and, where the drill's catalogue entry allows it, hand-held drilling.
• Materials rated Optimal for this drill: non-alloy steel, about 0.45 %C, quenched and tempered (250 HB); non-alloy steel, about 0.75 %C (annealed and quenched and tempered); low-alloy steel, quenched and tempered (275 to 350 HB); and brass.
• Also rated Effective: high-alloy and tool steel; austenitic stainless steel; duplex stainless steel; grey cast iron; nodular cast iron; malleable cast iron; hardened steel (45 HRC); and chilled cast iron.

Finish

Colour temp.

Cutting speeds and feeds

Cutting speeds (Vc) and feed numbers for this drill are from the Sutton Application Guide. The table lists the material groups covered, with the speed and the rpm and feed it works out to at Ø6 mm and Ø10 mm. Speed (rpm) = Vc × 1000 ÷ (π × Ø). Treat these as starting values and adjust for the machine, set-up and coolant.

Feed rates (mm/rev) for the feed numbers above:

Drilling notes

• Step feeding or pecking is required for holes deeper than 3 × Ø.
• When drilling a cast or black (not machined) surface, reduce the drilling speed by 20%.
• For optimal positional accuracy and hole size, spot the hole first with a Sutton spotting drill (D175).
• For hole depths greater than 7 × Ø, pre-drill a pilot hole first for accurate hole position and to stop the drill wandering. The pilot can be drilled with a short, rigid drill, about 3 × Ø deep, at reduced feed.

Deep holes: reduce speed and feed as hole depth increases.

Accuracy

Sutton drills are ground to an h8 diameter tolerance (the diameter may be at nominal or smaller, never larger) with a small back taper behind the point.

Troubleshooting

• Drill breaks. Dull point: sharpen; Drill has front taper due to wearing: sharpen; Insufficient lip clearance on point: grind correctly; Lip clearance too great: regrind to correct clearance angle.
• Outer corner breaks down. Flutes clogged with chips: remove drill from hole and clear the flutes; Cutting speed too high: reduce speed; Dry cutting, no lubricant at cutting edges: apply cutting fluid.
• Cutting edges chip. Lip clearance too great: regrind to correct clearance angle; Feed too heavy: reduce feed.
• Hole rough. Dull point: sharpen; Feed too heavy: reduce feed; Dry cutting, no lubricant at cutting edges: apply cutting fluid; Fixture/clamping not rigid: secure job firmly.
• Hole oversize. Unequal angle or uneven length of cutting edges: regrind to same lip lengths and angles; Spindle run-out / loose spindle: check machine.

Key specifications

Related drilling products

Compare other Sutton drills: D101 Silver Bullet, D179 Viper Plus, D180 R40 Inox and D202 left-hand cobalt. Sets are in the Metric Jobber Drill Sets and the Imperial Jobber Drill Sets. Need help choosing? Our guide to choosing the right drill bit and drill bit selection guide cover drill types and materials, and the speeds and feeds chart and cutting tool troubleshooting guide cover speeds and common problems. The cobalt drill bit guide explains cobalt grades.