Quick answer: a DTH drill bit is compatible only when its shank geometry matches the hammer's chuck and internal drive system. Nominal hammer size or bit diameter alone is not enough. Before ordering, confirm the exact hammer make and model, supported shank style, required bit diameter, foot-valve or tubeless configuration, and—when identification is uncertain—a drawing or verified part reference.
This matters because several different shank families can exist within the same nominal hammer class. Mincon, for example, lists DHD340, TD40, MD4, MQ40, MP40 and MC43 across its 4-inch hammer range, while Epiroc specifies TD40 for COP 44 Gold and QL50 for COP 54 Gold. Those interfaces should never be treated as interchangeable simply because the hammers or bits are described as “4 inch” or “5 inch.”
1. What Is the Shank on a DTH Drill Bit?
The bit shank is the rear section of the DTH bit that enters the hammer. It is not the thread on the top of the hammer. The shank carries the mechanical and pneumatic interfaces that allow the hammer to rotate, retain and strike the bit.
Depending on the hammer family, the shank can include:
- drive splines that engage the hammer chuck;
- a shoulder and retaining geometry that control axial movement;
- air passages that route flushing air through and around the bit;
- a bore for a foot valve on tubed designs, or a tubeless air path on designs that do not use a foot valve;
- specific lengths and diameters that position the bit correctly relative to the piston and chuck.
Do not confuse the bit shank with the hammer backhead thread. A hammer can have an API 2 3/8 Reg or API 2 7/8 Reg drill-pipe connection while using a completely different bit-shank family on the lower end. Both interfaces must be correct, but they solve different compatibility problems.
2. Why Hammer Size Alone Does Not Confirm Bit Compatibility
“4-inch hammer” and “5-inch hammer” are useful system-size descriptions, but they do not uniquely identify the bit interface. OEM data shows that one nominal size class can support several shank standards.
| Information you have | What it tells you | Is it enough to order? |
|---|---|---|
| Nominal hammer size | Approximate system class | No |
| Hole or bit diameter | Required cutting diameter | No |
| Hammer brand only | Narrows the product family | No |
| Exact hammer model | Usually identifies supported shank family | Often, but verify revision/configuration |
| Exact shank designation + bit diameter | Defines key mechanical interface and cutting size | Usually yes, after foot-valve check |
| Drawing or sample dimensions | Confirms geometry when naming is uncertain | Best verification method |
A useful real-world example is Epiroc's COP Gold range: COP 44 Gold is specified with a TD40 shank, COP 54 Gold with QL50, and COP 64 Gold with QL60. The model number is therefore not itself the shank designation. The hammer documentation is the authority.
3. Common DTH Shank Families Buyers Encounter
DTH markets use several established shank families. Names such as DHD, QL, TD, SD and manufacturer-specific interfaces are common, but the label must be tied to an exact size and hammer specification.
OEM catalogs demonstrate why visual similarity is not enough. Mincon's current DTH bit table, for example, lists differences in spline count and foot-valve configuration among shanks such as DHD340, TD40, QL50, DHD350, QL60 and DHD360. Two bits with similar head diameters can therefore have different drive geometries behind the head.
| Example shank | OEM example | Compatibility lesson |
|---|---|---|
| DHD340 | Listed by Mincon in the 4-inch class | Do not substitute another 4-inch shank without hammer confirmation |
| TD40 | Used by Epiroc COP 44 Gold | Hammer documentation identifies the required interface |
| QL50 | Used by Epiroc COP 54 Gold | Nominal 5-inch class does not mean every 5-inch shank fits |
| QL60 | Used by Epiroc COP 64 Gold | Size family and shank family must both match |
These examples are identification references, not a universal cross-brand interchangeability statement. Always check the hammer's approved shank specification before procurement.
4. Foot Valve vs Tubeless: The Compatibility Check Buyers Miss
The shank designation is only part of the decision. You must also confirm whether the hammer is designed for a bit with a foot valve or for a tubeless/no-foot-valve bit.
Mincon's current hammer documentation shows both configurations within the same nominal hammer class: some 4-inch variants use foot-valve bits, while MQ and MC variants are designed for bits without a foot valve. Boart Longyear similarly states that its BT hammer bits are tubeless, while some 5-inch and 6-inch bits can be supplied with an optional foot valve for traditional tubed hammers.
That means a purchase order that says only “4-inch DTH bit” can still be wrong in three independent ways:
- wrong shank geometry;
- wrong bit diameter for the required hole;
- wrong foot-valve/tubeless configuration.
Do not remove or add a foot valve in the field simply to make an incompatible bit “look right.” The hammer's internal air circuit determines which configuration is required.
5. A 7-Step Workflow to Match a DTH Bit to a Hammer
- Record the exact hammer make and model. Use the nameplate, service manual, purchase record or verified part number—not a verbal description such as “5-inch hammer.”
- Check the OEM shank specification. Find the supported shank style in the hammer manual, data sheet or current manufacturer catalog.
- Confirm the bit diameter. Match the cutting diameter to the required hole size and the hammer's permitted bit range.
- Confirm foot valve or tubeless design. Treat this as a separate compatibility item.
- Check spline and shank geometry if identification is uncertain. Count splines where useful, but do not rely on spline count alone. Measure key diameters, lengths and shoulder positions against a drawing.
- Compare the old bit or approved part number. A known-good sample is valuable when equipment documentation is incomplete, especially on mixed fleets or older hammers.
- Send enough evidence to verify the interface. Hammer model, photos, shank designation, bit diameter, foot-valve requirement and a dimensioned drawing eliminate most preventable ordering errors.
6. What to Measure When the Shank Name Is Unknown
If the hammer nameplate is missing or the shank designation is uncertain, do not guess from the bit face. The useful evidence is on the rear of the bit and inside the hammer chuck.
Provide the supplier with:
- clear photos of the complete old bit from front, side and rear;
- close-up photos of the spline area and shank end;
- number of drive splines;
- major shank diameter and relevant step diameters;
- overall shank length and shoulder positions;
- presence, outside diameter and length of the foot valve if fitted;
- hammer chuck photos and any readable hammer markings;
- old bit part number, drawing number or packaging label if available.
A spline count can narrow the possibilities but is not a complete specification. Mincon's catalog, for example, lists several different shanks with the same spline count. Geometry, length, air path and retaining features still need to agree.
7. Procurement Mistakes That Create the Most Downtime
| Mistake | Why it fails | Better purchasing control |
|---|---|---|
| Ordering by hammer size only | Several shank families can exist in the same nominal class | Specify exact hammer model and shank |
| Ordering by bit diameter only | Head diameter does not define the rear interface | Specify diameter + shank + foot-valve status |
| Assuming same spline count means same shank | Other diameters, lengths and air-path features can differ | Use OEM designation or drawing |
| Confusing API thread with bit shank | Backhead thread connects drill pipe; shank connects bit to hammer | Document both interfaces separately |
| Ignoring tubeless vs foot-valve design | Hammer air circuit and bit configuration may not match | Confirm foot-valve requirement before order |
| Mixing fleet records | Similar-looking hammers can use different chucks/shanks | Maintain model-specific approved-tool records |
8. RFQ Checklist for DTH Drill Bits
For faster compatibility confirmation, include the following in your RFQ:
- hammer manufacturer and exact model;
- required shank designation, if known;
- required bit diameter in mm or inches;
- foot valve required / no foot valve / unknown;
- rock type and drilling application;
- preferred face design and carbide profile, if already standardized;
- photos of the old bit and hammer chuck for replacement orders;
- old part number or dimensioned drawing where available;
- planned quantity and any inspection/documentation requirements.
PerfoMax's current DTH Tools range is organized around bit selection by hammer shank, hole diameter and rock condition. If the shank is uncertain, send the hammer model and identification photos through the Request a Quote page before ordering.
9. Frequently Asked Questions
Can I use any 4-inch DTH bit in a 4-inch hammer?
No. “4 inch” describes the general hammer class, not a universal bit interface. Current OEM catalogs show multiple shank families in this size range. Match the exact shank specification and foot-valve configuration.
Are DHD and QL shanks interchangeable?
Not by default. They are different shank families. A specific hammer may be offered in variants that support different industry-standard shanks, but the chuck and internal configuration must be designed for the chosen shank. Verify the exact hammer variant.
Can two different hammer brands use the same DTH bit shank?
Sometimes, because many manufacturers support established industry-standard shanks. However, brand compatibility should be verified from the hammer's approved shank designation, not assumed from size or appearance.
How do I know whether my DTH bit needs a foot valve?
Check the hammer manual or current OEM data sheet. Some hammer families are designed for foot-valve bits, while others use tubeless bits. If documentation is unavailable, provide the existing bit, hammer model and chuck/shank photos for technical confirmation.
Is the API thread size enough to identify a DTH bit?
No. API thread identifies the connection between the hammer backhead and the drill pipe. The DTH bit uses a separate shank interface at the lower end of the hammer.
10. Technical References
- Mincon — 4-inch DTH hammers: shank support and foot-valve configurations
- Mincon — DTH drill bits: shank types, spline counts and foot-valve data
- Epiroc — COP Gold series: hammer model, shank style and recommended hole range
- Boart Longyear — DTH bits: QL/QLX shanks and tubeless/foot-valve configurations
Match the Interface Before You Order
The lowest-risk DTH bit order starts with the hammer interface, not with the bit face. Confirm hammer model → shank style → bit diameter → foot-valve/tubeless configuration, then select face design and carbide profile for the rock conditions. That sequence prevents a technically good bit from becoming an unusable part simply because the interface was wrong.