H22 tapered tools can be used to drill roof-bolt holes only when the approved ground-support plan, the rock-drill configuration and the complete rod/bit interface all agree. The practical controls are straightforward: freeze the required hole diameter, depth and direction; use a drill and feed arrangement intended for upward or inclined work; keep the H22 drill steel aligned; maintain effective flushing; and verify the finished hole before the bolt or anchor is installed.
This guide covers hole preparation with H22-class tapered drilling tools in underground hard rock. It does not design the support pattern, choose a bolt system or authorize work under unsupported ground. Those decisions belong to the mine or tunnel ground-control plan, the support-system supplier and competent site personnel.
First define the boundary: the hole serves the support design
A roof-bolt hole is not accepted because the drill reached an approximate depth. Its geometry must suit a defined support component and installation method. Before selecting the drill steel or bit, obtain the controlled requirement for:
- hole position, direction and permitted deviation;
- required diameter and any tolerance or reaming instruction;
- required depth and how it will be measured;
- bolt, anchor, resin or grout system to be installed;
- hole-cleaning method and acceptance criteria;
- ground conditions, water conditions and stop-work triggers;
- the equipment and work sequence approved by the site.
Do not infer these values from a catalog bit size. A bit that fits an H22 rod may still produce the wrong hole for the planned support system. Mine Health and Safety Council roof-bolting guidance, for example, emphasizes drilling to the required depth and cleaning with the system specified for bolt installation. NIOSH roof-bolter training similarly treats a straight, clean hole as an operating objective. These principles are useful globally, but the local support plan remains controlling.
Confirm that the drilling arrangement fits upward work
H22 × 108 mm describes a common hex-shank class; it does not prove that every drill using that shank is suitable for overhead drilling. A handheld sinker, an air-leg drill and a stoper have different support and feed arrangements. For vertical or steeply inclined roof holes, a machine designed for that orientation may be required. Atlas Copco, for example, describes its BBC 34 WS-6 stoper as intended for vertical or inclined work including roof bolting, and separately lists its hole range and H22 × 108 mm shank. That is evidence for that model—not permission to copy its limits to another drill.
If the site proposes an air-leg drill rather than a stoper, confirm the exact drill, air-leg, working envelope and overhead procedure. The support device must keep the drill stable without forcing the steel away from the approved axis. Never improvise a support or use the air leg beyond the manufacturer's operating geometry.
Lock the complete H22 interface chain
| Interface | What to confirm | Why it matters |
|---|---|---|
| Rock drill to shank | Exact drill model, chuck and H22 shank length/class | A shared hex size alone does not prove full shank compatibility. |
| Shank to rod body | Straightness, collar condition, flushing entry and bore | Damage or blockage can disturb alignment and cuttings removal. |
| Rod to taper | Taper angle, socket condition and clean seating surfaces | Mismatched or damaged tapers can seat poorly and load the connection unevenly. |
| Taper to bit | Bit profile, diameter, gauge condition and flushing outlets | The bit must suit both the rock and the support-hole specification. |
| Drill to utilities | Dynamic air supply, lubrication and approved air/water flushing path | Weak percussion, dry running or poor flushing can make hole control unreliable. |
For current PerfoMax supply, the commercial route is the H22 × 108 mm tapered drill rod with an 11° connection option. Treat that page as an inquiry starting point: the quotation must still freeze length, taper, shank, bit and application. If the interface is uncertain, use the published H22 × 108 drill-steel compatibility guide before ordering.
Eight-step roof-bolt hole drilling workflow
1. Release the workplace under the ground-control procedure
Only enter and work in the area after the site has inspected the roof and ribs, controlled loose ground and established the approved support sequence. Barricade or control the drilling zone as required. If conditions differ from the support plan, stop and escalate; a tool selection guide cannot resolve an unexpected ground-control condition.
2. Mark the collar and direction from the approved layout
Transfer the hole position and direction using the site's permitted method. Check for services, previous holes, sockets, cracks or other prohibited targets. Confirm that the drill, feed device and operator position can follow the required line through the full stroke without a collision or unstable stance.
3. Inspect the drill steel and bit
Remove bent, cracked, mushroomed or otherwise rejected steel from service. Check the shank, collar, taper, bit socket and carbide condition under the site's inspection rule. Verify that the central bore and bit outlets are open. A clean external surface is not evidence that the internal flushing path is clear.
4. Establish a stable feed line before collaring
Place the machine so the thrust line, chuck, rod and intended hole axis are collinear. Misalignment at the collar tends to persist as the hole advances. Use controlled initial feed and percussion according to the exact drill manual; do not use maximum thrust to force a wandering bit back onto line.
5. Collar without skidding or side-loading the rod
Start the hole with the approved reduced-energy technique until the bit is captured. Watch the steel from a safe position for whip, bowing or eccentric rotation. Stop if the support slips, the collar breaks out, the rod bends visibly or the bit cannot establish a stable seat.
6. Drill with balanced percussion, rotation, feed and flushing
Advance only while cuttings return continuously and the steel remains stable. Too little feed can allow bouncing; excessive feed can stall rotation, reduce effective percussion or bend the steel. The correct balance is model- and rock-dependent, so use the controlled operating instructions and a healthy-tool baseline rather than a universal pressure or feed number.
Flushing must reach the bit and provide a return path around the rod. A clear return indicates that the system is moving broken rock out of the hole; it does not by itself prove the final hole is clean or within geometry.
7. Stop on abnormal return or ground response
Pause and reassess if cuttings suddenly stop, flushing pressure changes, water loss increases, the hole begins to collapse, the bit repeatedly binds, the steel deflects or the roof condition changes. Do not keep increasing feed or percussion to overcome an unknown obstruction. Withdraw or recover the tooling only under the approved procedure.
8. Finish, clean and verify before installation
Measure depth by the approved method and complete the specified cleaning cycle. Do not assume that withdrawing a wet rod leaves an installation-ready hole. Confirm the required diameter, depth, direction and cleanliness, then record any overbreak, collapse, water inflow or drilling anomaly that could affect the anchor installation. A rejected hole must be dispositioned under the support plan—not casually reused or relocated.
Adjust the plan to the drilling condition
| Condition | Primary risk to the hole | Practical response |
|---|---|---|
| Competent, abrasive rock | Gauge wear changes the produced diameter; slow penetration encourages overfeeding | Track bit gauge and wear, keep the bit sharp/serviceable and compare drilling response with a known baseline. |
| Fractured or laminated roof | Collar breakout, deflection, local collapse or binding | Use the support plan's method, controlled collaring and explicit stop-work criteria; do not solve a ground problem by force. |
| Water-bearing hole | Return flow may mask cuttings, erode weak zones or interfere with the planned anchoring process | Record inflow and follow the support-system supplier's cleaning and installation limits. |
| Restricted heading | Rod length or feed geometry prevents a straight approach | Select a permitted rod sequence that fits the working envelope. The H22 drill-rod length guide explains the selection inputs. |
| Poor cuttings return | Regrinding, heat, jamming and an incompletely cleaned hole | Check source flow, hoses, water path, rod bore and bit outlets before assuming the rock is the only cause. |
Hole acceptance checklist
- The hole is at the approved location and direction.
- Measured depth meets the controlled requirement.
- Diameter and condition are suitable for the specified anchor system.
- The cleaning method and completion criteria were followed.
- No unresolved collapse, blockage, excessive water or deviation was observed.
- The hole identity and drilling anomaly record are traceable to the installation.
- The next installation step can begin within the support plan's permitted sequence and time window.
Common mistakes that create avoidable risk
- Choosing the bit from the bolt's nominal size alone. The anchor supplier's hole specification controls.
- Treating H22 as a complete compatibility statement. Shank, length, taper, bit and flushing still need confirmation.
- Using feed pressure to correct poor alignment. Correct the machine position and support geometry instead.
- Continuing when cuttings return stops. A blocked path or collapsing hole needs diagnosis, not more energy.
- Installing into an unverified hole. Depth without cleanliness and geometry is incomplete acceptance.
RFQ data for H22 roof-bolt drilling tools
Send the supplier a controlled application sheet rather than “H22 rods for roof bolting.” Include:
- mine or tunnel application and drilling orientation;
- exact rock-drill model, maker and shank requirement;
- approved hole diameter, depth and direction range;
- rock description, fracture condition and expected water;
- rod length sequence and available working clearance;
- taper angle, current bit reference and flushing method;
- photos or drawings of the shank, rod, taper and bit interfaces;
- quantity, inspection evidence, packaging and delivery terms.
Frequently asked questions
Can an H22 tapered drill rod be used for roof-bolt holes?
Yes, when the approved drill is intended for the orientation, the complete H22 shank/rod/taper/bit chain matches, and the resulting hole meets the support system's controlled diameter, depth, direction and cleaning requirements. H22 alone is not approval.
What bit diameter should be used for a roof-bolt hole?
Use the diameter specified by the bolt, resin, grout or anchor-system documentation and the site's ground-control plan. Do not choose from the rod size or a generic catalog range. Also control bit wear because a worn gauge can change the produced hole.
How do you keep an upward hole straight?
Start with a stable machine and support, align the thrust line with the marked axis, collar under controlled energy and avoid side-loading the steel. Stop and reset if the support slips or the rod bows; additional feed cannot repair a poorly established axis.
Is water flushing always required?
No universal answer applies. Use the exact drill manual, site dust-control procedure, ground condition and anchor installation specification. Water can improve cuttings removal and dust control in many setups, but the permitted method and flow must be defined for the application.
What should the crew do if cuttings stop returning?
Stop advancing and investigate the flushing source, hoses, ports, rod bore, bit outlets and possible hole collapse under the approved procedure. Do not compensate automatically with higher feed or percussion.
Prepare a configuration-controlled inquiry
PerfoMax can review an H22 roof-bolt drilling inquiry when it includes the support-hole specification, exact rock drill, rod length, taper, bit, flushing method and ground conditions. Start with the H22 × 108 mm tapered drill rod and send the interface photos and controlled hole requirements with your request. Final suitability remains subject to the equipment manuals, the anchor-system instructions and the site's approved ground-support plan.