Start with hole diameter and ground conditions, then check the machine configuration
Top-hammer drill rigs and DTH drill rigs can stand in the same quarry yet still be built for different jobs. The right starting point is the blast design: hole diameter, bench height, planned hole depth, rock hardness and abrasiveness, required straightness and production targets. A familiar brand or a low purchase price cannot make up for the wrong drilling method.
To get a useful shortlist, provide the minimum and maximum hole diameters, typical depth and maximum depth, a rock description, bench access, and the tooling already in use on site. If these inputs are unknown, provide photos of the working face, existing drilling records, or the bit and drill rod sizes used by the current contractor. This evidence is more valuable than asking about a generic “quarry drilling rig.”
What changes between top-hammer and DTH
In top-hammer drilling, the rock drill above the drill rod applies the impact energy. The energy is transmitted through the drill rod and couplings to the bit. It is widely used in quarrying and civil engineering, where mobility, faster rod handling, and small to medium blast holes are important. Drill rod condition, couplings, shank bushings, rock drill condition, and feed alignment all strongly affect performance.
DTH drilling places the hammer behind the bit down the hole. Compressed air drives the hammer and clears the cuttings. This arrangement is typically used for larger or deeper production holes and straight-hole requirements, but the air compressor is part of the drilling system, not an accessory. Pressure, air volume, hammer size, drill pipe size and dust control must be matched as a whole.
Check reference specifications and the machine configuration
The current Epiroc document classifies the FlexiROC T35 under the top-hammer category, with a published hole diameter range of 64–115 mm, while the FlexiROC D55 is a DTH rig with a published hole diameter range of 90–152 mm. Configuration, market and year of manufacture all vary. A used Atlas Copco-era machine may not match the current sample, so the model name only identifies a series; the nameplate, the rock drill or rotary head, the air compressor nameplate, the drill rod system and the installed options are what determine the specific machine.
The T40’s applicable range depends on its installed rock drill and thread system. When considering a D55 for 90 mm holes, especially for shallow holes or restricted site access, verify the individual machine’s compressor configuration, measured transport weight and compatibility of consumables before deciding whether it is suitable.
Putting Both Options in the Same Purchasing Comparison Table
Each candidate machine should correspond to an equipment number and a nameplate photo. Separately record the actually installed rock drill or rotary head, drill rod system, drilling tools and air compressor configuration; mark unclear items as to be verified, and do not apply the information for one series directly to another used machine.
The comparison table uses the same set of target hole diameter, hole depth, formation and production requirements. Manufacturer brochures are used to check model boundaries, while photos of the actual machine and inspection records are used to check the current configuration and condition; the two types of material are kept separate.
- Equipment ID, complete model, nameplate and documentation version
- Model and configuration of the rock drill or DTH hammer, drill rods and drill bits
- Installed configuration and inspection records of the air compressor and dust-removal system
- What the quote covers in terms of drilling tools, tooling, spare parts and repair items
- Actual shipping dimensions, weight and site access conditions
Comparing Complete Drilling Systems and Cost per Hole
Assess the seller’s short drilling video in light of bit condition, flushing, operator skill and the rock tested. Compare cost per qualified hole: fuel, drill rods or casing, couplings, bits, hammer or drifter repairs, compressor servicing, dust filter elements, labor and non-drilling time.
Top-hammer buyers should check recorded percussion hours, visible rod thread wear, shank lubrication, feed-beam play and rod changer timing. DTH buyers should also check compressor load, working pressure under drilling load, compressor airend leaks, temperature stability, hammer lubrication and pipe threads. For both systems, qualified personnel should arrange an operating test relevant to the job under the equipment manual, site safety conditions and permitted operating conditions, recording the duration and results. The duration should be determined according to the equipment and site conditions.
Used equipment inspection points to distinguish the two methods
A continuous video may be requested from a cold start, identifying the machine and showing relevant drilling functions demonstrated by qualified personnel under the equipment manual, site safety conditions and permitted operating conditions. Where safe, the video may show the hour meter (without presenting it as independently verified), the engine compartment before warm-up, boom and feed movement, rod handling, dust collection and travel. Any edits should be explained; any necessary on-site repetition should be performed by qualified personnel under permitted conditions.
- Top hammer: rock drill identification, leaks, accumulator history, shank area, feed alignment and drill rod support
- DTH: compressor valve plate, loading pressure, temperature, unloading behavior, air leaks and hammer lubrication system
- Both include: cold start, exhaust, hydraulic temperature, structural repairs, track wear, emergency stop and maintenance records
- Confirm which drill rods, bits, hammers, tools and spare parts are included in the quote
Transport and site access conditions can change the decision
Larger DTH drilling rigs may shorten drilling time, but they may also increase inland transport, port handling and site-access costs. Ask for the measured shipping dimensions and weight in the actual shipping configuration, including any components that must be removed. Also check road restrictions, crane capacity at the destination, ramp angles, and the machine’s ability to work on the planned bench.
A worn rock drill, damaged feed or mismatched drill-rod system can create immediate repair costs. For DTH, where straight holes, larger hole diameters and sufficient production justify the air system, the total cost per meter of acceptable blast hole can be competitive.
Information to Include in a Quote Request
Please send a requirements form. Please specify the country and nearest port, application, rock type, hole diameter, depth, bench conditions, estimated working hours, emission requirements, preferred brand, budget range, and required delivery date. Please state whether you need only the drilling rig or a complete package including drill rods, drill bits, DTH hammers, air compressor support, spare parts, and export shipping.
GLOBMACH can then compare the current T35, T40, D55 and similar equipment against the same requirements. The reply should explain why each shortlisted machine fits, which configuration points remain unverified, and what inspection evidence is still needed. This produces a useful inquiry and reduces the risk of buying an impressive machine that is unsuitable for the drilling task.
