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.
Shank Selection Decision Guide
Choosing the correct shank type before buying bits saves money and prevents frustrating compatibility problems on the job. Work through the questions below in order.
Step 1 — What is the drill?
Standard keyless or keyed chuck drill (no hammer function): use round or hex shank bits rated for that chuck diameter. SDS-Plus hammer drill: use SDS-Plus shank only. SDS-Max hammer drill: use SDS-Max shank only. Router or CNC spindle: use straight-shank bits with the correct collet size.
Step 2 — What material are you drilling?
Wood or soft materials: round shank HSS or brad-point, no impact needed. Metal: round shank HSS, cobalt, or carbide-tipped; never use hammer mode. Masonry/brick at moderate depth: SDS-Plus carbide masonry bit. Reinforced concrete or rock: SDS-Plus for holes under 32 mm; SDS-Max for larger or deeper holes.
Step 3 — Is torque transfer critical?
If the bit tends to slip under high torque (common with large wood-boring bits or step drills in thick steel), switch to a hex shank in a hex-compatible chuck. Hex shanks cannot slip in a hex collet under any practical load. This is the main reason hex shank impact-driver bits have replaced round shank for most trades use in wood and light metal.
Shank Torque and Impact Rating Summary
| Shank Type | Typical Max Torque | Impact Rated? | Slippage Risk | Chuck / Holder Needed |
|---|---|---|---|---|
| Round (3-jaw chuck) | 40–80 Nm | No | Moderate at high torque | Standard keyless or keyed chuck |
| Hex 1/4" (6.35 mm) | 50–100 Nm | Yes (impact driver) | Very low — 6 flat faces lock | Impact driver or hex bit holder |
| Hex 3/8" or 1/2" | 100–250 Nm | Partial | Very low | Hex collet chuck or square drive |
| SDS-Plus | Up to 10 Nm rotary + impact | Yes (hammer drill) | None — axial float design | SDS-Plus chuck only |
| SDS-Max | Up to 20 Nm rotary + high impact | Yes (heavy hammer) | None — axial float design | SDS-Max chuck only |
| Spline | Up to 20 Nm + high impact | Yes | None | Spline chuck only |
Note: SDS systems are designed for low rotary torque combined with high axial impact. They are not suitable for high-torque rotary applications such as large-diameter wood-boring or hole-cutter work — use a standard chuck drill for those tasks.
Related Procurement Programs
If you are sourcing this product line for a distributor, importer, or private-label channel, these OEM and wholesale programs cover the procurement questions buyers usually ask next.
- SDS Chisels & Demolition Accessories OEM Manufacturer — SDS-Plus and SDS-Max chisel manufacturer and OEM supply for importers, distributors, rental companies, and private-label brands: point, flat, wide, gauge, and s…
- Metal & Concrete Drilling Tools Distributor Program — A practical OEM supply program for distributors who need both metal drilling and concrete drilling tools: SDS bits, HSS twist drills, M35 cobalt, step drills…
