Reference Guide
Metal Drilling
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METAL DRILLING
155
Step Drill Bits
IRWIN
®
UNIBIT
®
step drill bits are ideal for drilling holes in just about any type of thin material. General purpose high speed steel UNIBIT step drill
bits are perfect for use in mild steel, copper, brass, aluminum, plexiglass, wood, and laminate. Our Titanium Nitride-coated (TiN) bits resist heat and
friction, which extends the life of the cutting edge six times longer than standard step drills. And, our Cobalt step drill bits are engineered with M35
Cobalt steel for maximum life when drilling in the toughest steel, including stainless steel. Most UNIBIT step drills are designed with a SpeedPoint
®
tip
that guarantees fast starts. They’re manufactured with a single-flute cutting edge that drills multiple sizes of true, round holes with precise step control.
Plus, the hole sizes are permanently laser-etched on the inside of the flute, so they can be easily identified throughout the life of the bit.
UNIBIT Step Drill Bits — Drill Multiple Hole Sizes with One Bit
UNIBIT Application Guide
UNIBIT Cobalt HSS
10231CB
• Engineered with M35 Cobalt steel for maximum
life when drilling in tough steel.
• SpeedPoint
®
tip for fast starts.*
Description
# of Hole
Sizes
Hex
Shank Size
Carded
Item #
#1 1/8"-1/2" (1/32" steps)
13
1/4"
10231CB
#2 3/16"-1/2" (1/16" steps)
6
1/4"
10232CB
#3 1/4"-3/4" (1/16" steps)
9
3/8"
10233CB
#4 3/16"-7/8" (1/16" steps)
12
3/8"
10234CB
#9 7/8" and 1-1/8"
for (1/2" and 3/4") KO
for (1/2" and 3/4") KO
2
7/16"
10239CB
#20 9/16"-1" (1/16")
Inc - Hole Enlarging
Inc - Hole Enlarging
8
7/16"
10220CB
#1M 4 mm-12 mm (1 mm steps)
9
1/4"
11101CB
#2M 4 mm - 12 mm (2 mm steps)
5
1/4"
11102CB
#3M 6 mm - 18 mm (2 mm steps)
7
3/8"
11103CB
#4M 4 mm - 22 mm (2 mm steps)
10
3/8"
11104CB
Cobalt Titanium Nitride (TiN) High Speed Steel (HSS)
Stainless Steel or Other Tough Materials
Repetitive Drilling
General Use
Description
# of Hole
Sizes
Hex Shank
Size
Carded
Item #
#1T 1/8" - 1/2" (1/32" steps)
13
1/4"
15101ZR
#2T 3/16" - 1/2" (1/16" steps)
6
1/4"
15102ZR
#3T 1/4" - 3/4" (1/16" steps)
9
3/8"
15103ZR
#4T 3/16" - 7/8" (1/16" steps)
12
3/8"
15104
#13T 1-1/8" (single hole)
1
7/16"
15313
#20T 9/16" - 1" (hole enlarging)
8
7/16"
15200
#21T 13/16" - 1-3/8" (hole enlarging)
10
7/16"
15221
UNIBIT HSS Fractional Titanium Nitride
(TiN) Coated
• Titanium Nitride coating resists heat and friction,
extending the cutting edge life up to six times
longer than other high speed steel step drill bits.
• SpeedPoint
®
tip for fast starts.*
Set:
15502
15101ZR
— SpeedPoint™ Tip
*included on all self-starting sizes except for #1
FEATURES
UNIBIT STEP DRILL BIT
1. SpeedPoint
®
tip for fast starts.
2. Geometry of single-flute cutting edge drills true, round holes and provides
maximum step control.
3. Laser-etched sizes inside flute for easy and permanent hole size identification.
4. Hex-shaped shank secures easily in drill. #1, #2, #10, and #12 sizes have a quick-change shank.
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