The shank is the end of the drill bit that clamps into your tool. Buying the wrong shank type means the bit either will not fit, or will slip and damage the chuck. This guide covers every major shank type and when to use each.
1. Straight / Round Shank
The standard for precision drilling. A smooth, cylindrical shank that clamps into a 3-jaw keyed or keyless chuck.
| Fits | Pros | Cons |
|---|---|---|
| All 3-jaw chucks (1.5–13 mm range) | Most accurate — perfectly centred. Wide diameter range available (0.1–80 mm+) | Can slip inside chuck under heavy lateral load if chuck is worn. Takes time to swap bits. |
Use for: HSS twist drills, wood bits, step drills — any precision drilling in metal, wood, or plastic where runout matters.
2. Hex Shank (1/4″ Quick-Change)
The contractor's time-saver. A 6-sided (hexagonal) shank that snaps into a quick-release bit holder or impact driver. The flat sides prevent rotation in the holder.
| Fits | Pros | Cons |
|---|---|---|
| 1/4″ quick-change holders, impact drivers, many cordless drills | Single-handed bit swap in under 2 seconds. No chuck key needed. Impact-driver compatible. | Limited to 1/4″ (6.35 mm) max shank diameter. Some runout on cheap holders. |
Use for: Screwdriving bits, small hole saws, countersinks, short masonry bits. Standard on all impact driver accessories.
3. SDS-Plus Shank
The construction standard for rotary hammer drilling. SDS-Plus (10 mm shank) uses four slots — two open (for the locking balls) and two closed (for torque transmission). The bit floats axially, meaning the hammer mechanism can drive the bit backward even while the chuck spins forward.
| Fits | Pros | Cons |
|---|---|---|
| All SDS-Plus rotary hammers (Bosch, Makita, Hilti, DeWalt, Milwaukee 2–5 kg class) | Maximum energy transfer in concrete. Tool-free bit change. Axial float absorbs hammer blows. | Cannot be used in standard drills without an adapter (which defeats the purpose). |
Diameter range: 4–26 mm standard; up to 32 mm with specialist bits.
Use for: Concrete anchors, masonry drilling, rebar detection holes, chiselling with SDS-Plus chisels.
4. SDS-Max Shank
Heavy-duty concrete work. SDS-Max uses an 18 mm shank with 5 slots (3 open, 2 closed). The larger engagement area handles the extreme torque and impact energy of 5 kg+ demolition hammers.
| Fits | Typical Diameter | Use |
|---|---|---|
| SDS-Max rotary hammers / demolition hammers (5 kg+) | Ø16–40 mm, lengths to 1200 mm | Large-diameter anchor holes, deep structural penetrations, wall-through-drilling |
SDS-Plus vs SDS-Max: Never mix them. An SDS-Plus bit will not lock into an SDS-Max chuck. Adapters exist but they reduce efficiency and should only be used briefly in emergencies.
5. Hex 19 mm / 22 mm Shank
Used on heavy-duty electric chisels and large demolition hammers. The large hexagonal engagement prevents rotation under the high torque loads of a 10 kg+ breaker. Common on ground rod drivers and heavy-duty chisels.
6. Spline Drive Shank
An older system (pre-SDS-Max) from Bosch and Hilti, now largely superseded. Spline bits have 12 serrated teeth around the circumference. They are still sold for older hammer drill models. Do not confuse spline with SDS-Max — they are incompatible.
Full Shank Comparison Chart
| Shank Type | Shank Ø | Tool Class | Max Bit Ø | Best Application |
|---|---|---|---|---|
| Straight / Round | 1–13 mm (chuck range) | Standard drill / drill press | 80 mm+ | Precision: metal, wood, plastic |
| Hex 1/4″ | 6.35 mm | Impact driver / quick-change | Up to 35 mm hole saws | Fast bit changes, light masonry |
| SDS-Plus | 10 mm | Rotary hammer (2–5 kg) | 26 mm (32 mm specialist) | Concrete, masonry, anchors |
| SDS-Max | 18 mm | Heavy demolition hammer (5 kg+) | 40 mm+ (with extensions) | Large holes, deep structural |
| Hex 19 / 22 mm | 19 / 22 mm | Heavy breaker (10 kg+) | Chisels only | Heavy demolition, chiselling |
| Spline | — | Older large hammer drills | 40 mm | Legacy equipment only |
Using Adapters Between Shank Types
Adapters exist to use SDS-Plus bits in a standard drill chuck, or hex bits in a 3-jaw chuck. As a rule:
- SDS-Plus → 3-jaw chuck adapter: Works for slow, low-impact drilling only. Never use the hammer function — it will destroy the chuck.
- 3-jaw chuck → SDS-Plus adapter: Allows standard round-shank bits in a rotary hammer. Useful for drilling wood or metal with an SDS machine. Acceptable for occasional use.
- SDS-Max → SDS-Plus adapter: Not recommended for extended use. The SDS-Max machine delivers far more impact energy than SDS-Plus bits are designed for.
刀柄选择决策指南
在购买钻头前选对刀柄类型，可节省成本并避免施工现场令人沮丧的兼容性问题。按顺序回答以下问题。
第一步——使用什么电钻？
标准无钥匙或有钥匙夹头钻（无锤击功能）：使用适合该夹头直径的圆柄或六角柄钻头。SDS-Plus冲击钻：只用SDS-Plus柄。SDS-Max冲击钻：只用SDS-Max柄。路由器或CNC主轴：使用与夹套尺寸匹配的直柄钻头。
第二步——钻什么材料？
木材或软材料：圆柄HSS或尖头钻，无需冲击。金属：圆柄HSS、钴合金或硬质合金刀头；禁用锤钻模式。中等深度砌体/砖：SDS-Plus硬质合金砌体钻头。钢筋混凝土或岩石：32 mm以下用SDS-Plus；更大或更深的孔用SDS-Max。
第三步——扭矩传递是否关键？
如果钻头在高扭矩下容易滑转（常见于大型木工钻头或厚钢板阶梯钻），换用六角柄配六角兼容夹头。六角柄在六角夹套中在任何实际负载下都不会滑转。这是六角柄冲击钻头在木材和轻金属作业中取代圆柄的主要原因。
刀柄扭矩与冲击额定值汇总
| 刀柄类型 | 典型最大扭矩 | 冲击额定 | 滑转风险 | 所需夹头/夹持器 |
|---|---|---|---|---|
| 圆柄（三爪夹头） | 40–80 Nm | 否 | 高扭矩下中等风险 | 标准无钥匙或有钥匙夹头 |
| 六角 1/4"（6.35 mm） | 50–100 Nm | 是（冲击起子） | 极低——六个平面锁定 | 冲击起子或六角刀头夹持器 |
| 六角 3/8" 或 1/2" | 100–250 Nm | 部分 | 极低 | 六角夹套夹头或方形驱动 |
| SDS-Plus | 旋转最高10 Nm+冲击 | 是（锤钻） | 无——轴向浮动设计 | 仅SDS-Plus夹头 |
| SDS-Max | 旋转最高20 Nm+强冲击 | 是（重型锤） | 无——轴向浮动设计 | 仅SDS-Max夹头 |
| 花键 | 最高20 Nm+强冲击 | 是 | 无 | 仅花键夹头 |
注意：SDS系统专为低旋转扭矩结合高轴向冲击设计，不适合大直径木工钻或开孔工具等高扭矩旋转作业——这些任务请使用标准夹头电钻。
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