🔧 How to Choose the Right Drill Steel for Pneumatic Drills
Selecting the correct drill steel and bit setup is essential for drilling performance, tool durability, and efficiency. Whether you’re working in rock, concrete, or underground conditions, choosing the right configuration will greatly improve job results. 💪⛏️
✅ Step 1 – Confirm Your Rock Drill Shank Size
Before buying drill steels or bits, identify the shank configuration your tool uses. Every pneumatic rock drill accepts a specific shank size, and using the wrong one means the tooling won’t fit. 🚫🔩
🔩 Common Shank Sizes for Handheld Drills
Most standard drills use one of three industry sizes:
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7/8" x 3 ¼"
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7/8" x 4 ¼"
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1" x 4 ¼"
The first measurement refers to the hex steel diameter, and the second is the length above the collar. Bigger drills usually use the 1" configuration, but exceptions exist.
Smaller pneumatic units (like CP9-style models) often use one-piece “whirly bits”, where the steel, shank, and carbide tip are manufactured as one tool.
📌 Bottom line: Know your shank size before ordering anything.
🎯 Step 2 – Choose the Steel & Bit System for Your Application
Once you know the shank, you can select the appropriate drilling setup.
🔁 One-Piece Carbide Whirly Bits (Speedrill or Integral)
Whirly bits combine:
✔ Shank
✔ Drill steel
✔ Carbide cutting head
The body is slightly smaller than the drilling diameter to help debris escape the hole.
⭐ Advantages
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Great for small-diameter holes (5/8" to 1")
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Fast drilling in shallow to medium depths
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No assembly required
⚠️ Limitations
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Higher cost than separate bits and steels
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Smaller diameters = reduced steel strength
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When worn, the entire tool must be replaced
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Not ideal for aggressive side-loading with large drills
🔗 H-Thread Steels
H-thread systems are the most commonly used in contracting—affordable, durable, and widely available. Rods typically feature a ~1" male thread and come in lengths from 12" up to 120" (10 feet).
🏗️ Construction Benefits
H-thread steels are forged and heat-treated for:
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Hard outer surface for wear resistance
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Tough core for shock absorption and energy transfer
⚠️ Important Operating Note
H-thread depends on the bit staying tight against the shoulder. If it loosens:
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Impact force hits the threads instead
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Thread damage or failure happens quickly
Maintain steady down-pressure and avoid drill bounce to maximize tool life.
⛏️ Tapered Drill Steel
Taper systems are most common in mining applications, especially with jackleg drills.
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🇨🇦 12° taper widely used in Canada
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🇺🇸 11° taper more common in the USA and Central America
The tapered bit is pressed onto the rod and removed using a knock-off tool when worn.
👍 Why Contractors Sometimes Choose Taper
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Mass-produced
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Affordable
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Reliable for mining use
⚠️ Drawbacks
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Limited sizing options
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Often based on 7/8" x 4 ¼" shanks
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If down pressure isn’t maintained, the bit can drop into the hole
🧵 Rope-Thread Systems (R25 / R32)
Rope threads like R25 (1") and R32 (1¼") are commonly used in demanding drilling conditions or for larger-diameter holes. They are frequently carburized, giving:
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Extremely hard exterior shell
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Slightly softer, shock-absorbing core
This improves thread life and overall tool performance in harsh drilling.
➕ Extension Capability
Rope-thread systems allow multiple rods to be linked, enabling:
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Deep hole drilling
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Long reach
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Work in tight or confined spaces
🧰 Available Drill Bit Types at MADIDO
💎 Carbide Cross Bits (Blade bit)
Long-lasting
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Holds gauge well
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Sharpenable
⛰️ Carbide Button Bits
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Multiple carbide “buttons” on the face
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Higher performance and speed in the right rock
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Slightly higher price
🏁 Conclusion
Choosing the right drill steel and bit setup starts with understanding your shank size, then selecting:
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One-piece systems for quick and simple drilling
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H-thread systems for flexible general contracting
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Taper systems for traditional mining setups
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Rope-thread systems for deep, tough drilling conditions
The right choice = faster work, longer tool life, and better job results. ⚙️🔵