In all this time, this system (seen in photo on the right) has had the same basic issues:

Spearhead Handling: in up-hole applications underground, a driller is required to manually push the head assembly into the hole by the spearhead. Since it has a pointed end and pivots by design, it can be difficult to handle this operation comfortably.

Inner Tube Handling: When hoisting the inner tube assembly, elastic action of the wireline cable or accidental impact during handling can un-load cable tension and overcome spring loads which allows the hooked lifting dogs to accidentally release the spearhead. The surface ‘Ezy-Lock’ overshot includes a twist-sleeve that locks onto the spearhead even without cable tension, whereas competing overshots require cable tension to maintain a lock.

Lifting Dog and Spearhead Wear: To balance strength and wear resistance, lifting dogs and spear points are heat treated to a medium hardness. However, it’s difficult to visually evaluate or functionally test the degree of wear, especially in underground applications. 

Boart Longyear currently provides a secondary safety pin that clips through the overshot, passing just under the spearhead tip. This adds an extra layer of protection in case the lifting dogs are excessively worn or deformed. However, spearheads are loaded cyclically and often loaded ‘off-pivot’, which deforms the components over time, to the point of disassembly. While the more recent MKII version of the spearhead assembly is much more robust, in the case of spearhead failure, the head assembly will release from the overshot regardless of lifting dog or safety pin use or condition.

This patent-pending overshot leverages our previous experience with Roller Latch head assemblies to create a more reliable and longer lasting system that eliminates spearheads and lifting dogs entirely. The spearhead assembly is replaced by a one-piece socket receptacle (spearhead adapter) that accepts the overshot itself, which has rollers that latch into an internal groove in the spearhead adapter.

Swapping the pointed, jointed spearhead for a simple cylindrical socket makes for much easier handling of head assemblies in up-holes. Surface Quick Descent Roller Latch head assemblies don’t even require the spearhead adapter since the internal groove geometry was pre-built into their design.

The increased toughness and hardness of the bearing quality latch rollers have a proven history of outlasting traditional pivoting latches for wear life. The new overshot will also feature the same Nitreg-ONC surface treatment as Roller Latch head assemblies that drastically improves corrosion resistance (Nitreg is a trademark of Nitrex Inc.).

Safety pin integration in the new underground Quick Pump-In overshot now pulls double duty of both locking the overshot from accidentally releasing while hoisting, as well as holding the head assembly and overshot together in case of component failure due to excessive wear. Also, the socket and rollers are not affected by side loading and ‘off-pivot’ loading during tube handling outside the hole, eliminating gradual deformation or disassembly. The new surface overshot will also include a one-hand twist-lock sleeve to maintain a locked position while hoisting outside the hole, even with a loss of wireline cable tension.

It’s also easy to use.  Instead of pushing the backs of the lifting dogs together, the driller pushes the two halves of the assembly together, retracting the rollers and releasing the head assembly. This operation takes about the same amount of force as the current overshot, so drillers won’t miss a beat.

Additional benefits have been included[CA1]  apart from the elimination of the spearhead and lifting dogs. While the current design uses a solid pivot pin that is peened into place (making it difficult to re-build), the Roller Latch Overshot has no pins whatsoever. Everything is held in place by simple threaded connections for easy maintenance.

First, in the event of a stuck tube, the driller needs to disengage and retrieve wireline cable in order to pull rods. Today, that is done by overloading and breaking a shear pin placed just underneath the cable swivel. In theory this pin breaks at under half the wireline cable’s max load capacity, but in practice its strength is highly variable because shear pins are inherently weak and ductile. Many operators remove the shear pin, which removes release capability and may result in excessive wireline cable replacement.

The Roller Latch Overshot features a brand new pump-in cable release system, originally conceptualized and prototyped by one of our expert underground drillers in Canada. A slotted sleeve and pumping seal assembly is placed over the wireline and pumped up to the overshot. The sleeve engages a quick-release mechanism and releases the wireline. This system has proven to be much more reliable, and may be the feature drillers are most thrilled to have going forward.  Reports of fewer broken wirelines have been received from several sites testing the pump-in cable release system.

Second, while Q/P Roller Latch head assemblies with built-in brake features have had great success in stopping runaway tubes and creating a safer drilling environment underground, they are perhaps “too” successful. Currently, when retrieving the head assembly from an inclined hole, pressure has to be applied to disengage the brake. Getting this pressure and procedure exactly right can be difficult, especially with hydrostatic pressure at depth.

To combat this and make Q/P Roller Latch easier to use while maintaining its safety features, a ‘brake release spring’ was created. This spring assembles quickly inside of the spearhead adapter on the head assembly. While tripping on its own, the head assembly brake works normally, but when the overshot latches into it this spring is compressed, disengaging the brake. This feature has also been received very positively by drillers in the field.

A surface-style overshot is also in development in B/N/H sizes. In addition to many of the features outlined in this article, the aim is to add more innovations, including:

• An improved lock sleeve to disable accidental head assembly release and stop drillers from accidentally sending the overshot down the hole while locked.

• A built-in 360° pivot and shorter overall length for increased ease of handling.

Excitement is high as testing continues. Drillers are noting the various positive developments: it’s easier to use, saves on wireline, and makes working with Q/P Roller Latch head assemblies much easier in difficult conditions. We’re looking forward to further field success as testing begins on the surface design.

For more information and downloads, visit: 
Roller Latch Quick Pump-In Overshot - Boart Longyear

What many people may not know is that the drillers and engineers of Boart Longyear have been involved in some exciting historical drilling projects in a variety of other applications, too. Drilling equipment for moon exploration is one such example (read Drilling Beyond Earth); but closer to home, the company has assisted with projects to explore and define foundation and structural integrity below the earth or even under bodies of water.

In the late 1920s, members of the Longyear team were contracted to test drill the route of a proposed vehicular tunnel under the East River to connect Manhattan to Brooklyn in New York, USA. The tunnel was intended to reduce transportation congestion due to the slow and unreliable ferry service that existed at the time. The Longyear company provided preliminary boring samples used to determine what was beneath the surface of the river. Characterizing the samples’ type of rock and its hardness allowed geologists and engineers to determine what equipment should be used for tunneling, how long it should take, and at what cost. Although the initial tunnel project didn’t receive support and funding, it laid the groundwork for a later project—the Brooklyn-Battery Tunnel—which was started in 1940 and opened in May of 1950.

A similar challenge of traversing a wide body of water required assistance from the Longyear team in 1929. Joseph B. Strauss, a visionary engineer, was tasked with his team to design the proposed Golden Gate Bridge in San Francisco, California, USA. As chief engineer, Strauss requested the services of Longyear to investigate the rock formations beneath the San Francisco Bay where the bridge would be constructed. Longyear started boring in the Bay in November 1929 along the sites of the proposed piers and anchorages. [i]

Due to the turbulent waters of the channel, the drillers had to be creative as to how they would retrieve the core samples beneath the tumultuous surface. Strauss was big on safety, requiring bridge workers use safety lines, work over safety nets, and even wear some of the first hard hats. The Longyear crew constructed a platform over the water supported by a boom—an A-frame—and guy-wires anchored to the shore. The platform allowed the team to suspend their drilling equipment securely on top and safely above the bay. Despite the problems of deep water, ocean traffic, storms, and tidal movement, the team was able to finish the work on schedule with complete core sample recovery.

The geological samples and subsequent data supplied to Strauss proved that the rock formations could bear the weight of the foundations and enable the huge bridge structure to be built. The information was provided in a full report to the board of engineers in February 1930 and the bridge was determined to be “feasible economically and structurally.”

This great news meant Strauss and his design team could move on to the next phases of engineering and constructing the Golden Gate Bridge. In gratitude for Longyear’s contribution, Strauss wrote, “The work done by your company, having been entirely satisfactory, and the relations between us and your drillers having been cordial and pleasant, I am glad to make immediate payment of the balance due.” [ii]  

Payments received by the company totaled close to $15,000 for the boring contract. It wasn’t for another three years (January 1933) that construction began and a groundbreaking ceremony for the bridge was held. The Golden Gate Bridge was completed in May 1937 at a total cost of $35,500,000.

Click below images to view larger.

From left to right

Images 1 and 2: “Engineers Speed Plans for Golden Gate Bridge” - A Pacific Street and Road Builder article from March 1930 stating “test borings reveal solid rock foundations and showing a photo of boring operations at the Lime Point side of the bridge in Marin County, California.

Image 3: “Borings Started for Gate Span” – Photos shows in the Vallejo California Chronicle, Sebastopol California Times, and Cresent City Triplicate newspapers on November 29, 1930. The article shows a photo of Longyear’s diamond-tipped drills used for bore sampling the rock at the San Francisco end of the bridge, next to Fort Point.

Image 4: “Getting Down to Bedrock” – A San Francisco Examiner article, dated February 14, 1930, picturing engineers, including Strauss, inspecting boring samples from the Golden Gate Bridge project.

A truck-mounted LS600 sonic rig taking core samples near a dam site.

Shortly after the Golden Gate boring project, the Longyear company became involved with drilling projects for the construction of hydro dams around the country. In the 1930s, Longyear drillers did test borings for several of the twenty planned dams under the jurisdiction of the Tennessee Valley Authority. These dams were part of a comprehensive plan for the reclamation and development of the Tennessee River—covering an area of more than forty thousand square miles and over seven states.[iii]

Later twentieth-century construction-type projects for Longyear drillers included boring for core samples for the Missouri River Project, and the first foundation test borings for the Fort Peck Dam in Montana—the project’s first major hydro dam.

Today, Boart Longyear continues to assist with construction and rehabilitation projects around the world using even more advanced technologies and equipment. The company regularly uses sonic drilling technologies which are ideal for avoiding many of the challenges experienced with conventional drilling methods.

Sonic drilling offers quality control in conjunction with the production and installation of geotechnical construction elements. The sonic method can actually eliminate the need for circulation-type drilling allowing the driller to work safely in situations that involve sensitive structures, vulnerable site conditions, difficult geology, or have restrictive conditions. Sonic drilling also provides measurements and samples to evaluate actual conditions across a given site during the progress of exploration and construction.

A few examples of Boart Longyear’s sonic drilling assistance with tunnel, bridge, and hydro dam projects in the twenty-first century include: [iv]

• Casing installation for the Boston Central Artery / Tunnel Project CO9A4, Massachusetts, USA. As part of the process of installing three jacked tunnels under the 13 railroad tracks at South Station in Boston, specialized sonic drilling was used to install casing through some of the most difficult combinations of historical fill materials—steel rails, brick tanks, woodpiles, granite seawalls, reinforced concrete slabs, track ballast rock, clay, stratified sands, till and weathered bedrock.

• Installation of a grout curtain at Clearwater Dam in Missouri, USA. The project required a drilling method with the ability to penetrate and sample both the body of the dam and its foundation without the use of air or water circulation. Sonic drilling was used to investigate a deep sinkhole and affected a remedial plan involving drilling 15-degree battered grout holes through embankment fill to construct a grout curtain.

• Sonic drilling comparison for a tunnel design pilot study on the Combined Sewer Overflow Control program, Anacostia River Project in Washington DC. Sonic drilling was used to perform continuous soil coring with approximately 100% core recovery and careful installation of multiple piezometers.

• Micro-pile installation testing near the Holland Tunnel in New Jersey, USA. Sonic drilling was compared with conventional drilling to advance micro-piles through silty sand overburden, overlying till, and schist. Not only was the sonic drilling 33% quicker for installation of the micro-piles, waste was also eliminated to nearly the volume of the sonic core, which minimized disposal costs. 

Bridges, tunnels, dams, and even buildings are all safer because of the work done to investigate, test, and secure the foundations. Although considered a small contribution to these engineering marvels, Boart Longyear employees are proud of the heritage the company has earned and its involvement in each part of history.

For more information on Boart Longyear’s construction drilling capabilities, including sampling core, anchoring, micro-piling, jet grouting, and ground freezing, visit the overburden and construction tooling section.

[i] https://www.goldengate.org/bridge/history-research/bridge-construction/joseph-strauss/

[ii] Edmund J Longyear, and Walter R Eastman. 1984. “The Mesabi and Beyond”; Pg 181

[iii] Edmund J Longyear, and Walter R Eastman. 1984. “The Mesabi and Beyond”; Pg 192

[iv] George R Burnhart, Boart Longyear Technical paper. 2006. “Sonic Drilling Offers Quality Control and Non-Destructive Advantage to Geotechnical and Construction Drilling on Sensitive Infrastructure Sites.”

Golden Gate Bridge Photos from historical records, the Golden Gate Bridge, Highway and Transportation District and found here https://www.goldengate.org/exhibits/engineering-the-design/

Golden Gate Bridge Photo courtesy of Umer Sayyam

Edge Drilling director, John Argiropoulos, recently took delivery of a Boart Longyear LS250 MiniSonic rig that is suited to a variety of soft ground, shallow drilling projects including environmental, tunneling, water management, grade control, leach pads, and tailings dams.

The rig delivers faster penetration for nearly undisturbed samples using little or no fluids, said John, and its casing system makes it ideal for a variety of applications including mining, environmental, and infrastructure projects.

The rig provides extremely accurate sampling for unconsolidated formations which makes it suited to mining, but it also eliminates the risk of cross contamination making it ideal for environmental and geotechnical work. It can also precisely drill straight holes at varying angles which ticks the box for infrastructure projects.

“We've already got five months of work lined up with the rig," John told Australasian Drilling.

The idea of acquiring a sonic rig first came to John during a visit to Christchurch in New Zealand where he saw the rigs undertaking post-earthquake recovery sampling work.

“I've been looking at getting into this type of drilling from the first time I saw it,” he said.

“After the earthquake in Christchurch, I saw massive advantages with sonic rigs in drilling overburden and getting near on 100 percent recovery sampling. The rigs were drilling every house in carports or garages and were looking for signs of liquefaction.”

Liquefaction is where the strength and stiffness of soil is reduced by earthquake shaking. If liquefaction was found following testing in Christchurch, the dwelling would be demolished.

“They had conventional rigs at the start including standard diamond drilling, but they weren't getting any core recovery, being glacial fill," John said. "However, the sonic rigs collected everything from pebbles and cobbles, to rock, clay, silt and sand. They were very impressive.”

With work increasing, John eventually took the plunge and invested in a sonic rig.

“We're getting much busier,” he said. “In the space of 12 months, we've gone from two rigs at the start of last year to seven rigs now. We've expanded quite a lot.”

John said work began to resurge since 2016. A big push by Main Roads WA (Western Australia) for testing bridges across the state is creating work from the rollout of the government's METRONET program and is expected to generate more construction activity and geotechnical work in the near future. The METRONET program is one of the largest single investments in public transport that Perth has seen and will involve about 72 km of new passenger rail and up to 18 new stations.

With enhanced capabilities thanks to the new rigs, John is upbeat in his outlook for the business. However, like most contractors, he is feeling the pain of skill shortages. John said he is managing the issue through in-house training.

"I'm a firm believer of training in-house as the best way forward because we can train personnel according to our standards, expectations, policies, and procedures.”

Originally published in Australasian Drilling Magazine, February/March 2020

The drill string’s resistance to deviation—otherwise known as ‘stiffness’—can be determined by its material and mechanical properties. Since all wireline tubular components are made from cold-drawn steel tubing, they all have the same fundamental properties. Specifically, regardless of chemistry, heat treatment, or hardness, all steel grades respond with the same amount of bend to a given load (the ratio of stress (load) to strain (bend) is known as the “modulus of elasticity”). Furthermore, any two steel tubular components with equal dimensions will have equal stiffness, even if produced by different suppliers, regardless of the steel grade, heat treatment, or hardness.

The directional response or sensitivity of the drill string to changes in drilling loads or speeds, or in formation changes, depends heavily on the drill string stiffness. The stiffness of wireline drill rods more than doubles in moving to the next larger system (e.g. BQ to NQ, NQ to HQ, etc.). As a result, larger systems drill straighter but have much more resistance and greater lateral loading when drilling through borehole deviations. Given a typical impregnated coring bit, and constant drilling parameters (assuming no formation changes), the borehole will tend to form a slow helix that is determined primarily by the stiffness of the drill string. With borehole friction, the drill string itself can become unstable, buckling into a helical shape which tightens or loosens with changes in drilling loads and speeds, but then elastically returns straight when unloaded.

The Q wireline core barrel was originally designed to utilize an outer tube with a substantially larger diameter and wall thickness than the unstable string of drill rods behind it. Standard outer tubes provide approximately 40% greater stiffness, and full-hole style outer tubes provide approximately 70% greater stiffness! The outer tube can then act as a stabilizing bearing or collar. The greater the increase in stiffness, the more effective a directional control to resist changes in the formation, drilling parameters, or drill string stability. This control can be enhanced with stabilized reaming shells, stabilized adapter couplings, and stabilized locking couplings.

Consider the directional impact if the outer tube is replaced with another drill rod, completely removing any difference in drill string stiffness, and the related directional control. Originally developed in the 1980’s in an attempt to direct borehole deviations, core barrel configurations, known as “flexi-barrels,” replace the outer tube with an equivalent length assembly of a drill rod and adapters. However, the lack of directional control combined with the lack of directional predictability, typically results in erratic deviations requiring either corrective deviation attempts or reaming to reduce excessive deviations. Therefore, the use of flexi-barrels is not recommended.

When planning holes, consider the potential impact of rod deviation. The stiffness of steel tubes is relatively high, and as mentioned before, increases with system size and section thickness. As a result, the drill string will respond with high side loads against the borehole wall, especially just before and after a deviation. For example, an NQ size drill rod deflected to the recommended maximum deviation of 1.0 degrees over its length produces approximately 9kN (2,000lb) of side load, and an HQ produces 18kN (4,000lb) at only 0.8deg per rod length. Depending on the formation, these high side loads can produce high torque, heavy rod wear or even ‘heat check cracking.’ Additionally, these contact points generate drag and ‘stick-slip’ conditions, which can produce a dynamic response sufficient to permanently deform the drill string into a helical shape. In extreme cases, where the drill string completes enough rotations approaching or exceeding maximum deviation, fatigue failures will occur. Using the minimum deviation possible to hit target and sticking to NQ size rod will reduce the side loads, torque and chances of twisting or cracking rod.

Originally published in Australasian Drilling Magazine, February/March 2020

Martin Rivet is the Director of Engineering for Drilling Services at Boart Longyear. Growing up in Haileybury, Ontario, he took an early interest in the mining industry, joining the company at age 16 as a mechanic’s assistant. He continued his education earning a degree in mechanical engineering and with his gained experience took on new positions as an engineer, an EHS professional, a product manager, and most recently, the director of the Drilling Services engineering team. Martin now lives in Salt Lake City, Utah working on global engineering projects, including the development and implementation of TruProductivity.

Our host, Jon Peterson (Geo Jon for fun), works for the Products division as a Customer Service Representative. Jon graduated from the University of Utah in 2015 with his Bachelors of Science in Geology. He’s worked for Boart Longyear for the last two and a half years and interned as a geologist with an exploration company for about six months prior to coming to work for Boart Longyear. Jon has been married for a year and a half and in his free time enjoys trail running, hiking, working on his yard, spending time with family, and playing with his black lab Dexter. 

We would love to hear your questions and comments below. Thanks for listening and if you liked this episode, share it on LinkedIn, Facebook, or Twitter. 

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Typically, manufacturing sonic drill rods is a three-piece construction process in which the rod ends are friction- or slip-fit and welded onto a mid-body. This allows manufacturers to use lower grades of steel in the mid-body to save on costs.

Boart Longyear utilizes an upset forging process in manufacturing its sonic drill rods. Upset forging refers to the process in which a drill rod begins its life as one single piece of high-grade steel tubing and is internally forged to ½” thickness on the thread ends which transitions to ¼” mid-body wall thickness. This eliminates welding the thread ends onto the mid-body, creating a significantly stronger one-piece-design sonic drill rod. 

At a high-level, the six manufacturing steps for sonic drill rods are:

1. Begin with high-grade steel tubing having 3 ½” outer diameter and ¼” wall thickness
2. Upset forge the rod ends to 9” in length and ½” wall thickness
3. Stress relieve the entire rod (heat and cool slowly)
4. Heat treat the rod pin and box ends (quench and temper) for strength and durability
5. Machine the pin and box tapered threads into the upset forged ends
6. Heat treat the pin thread a second time to a slightly higher hardness (increases life, prevents galling (rods seizing up into each other during drilling) and increases wear resistance)

This process, which draws on our vast experience manufacturing diamond coring rod, creates a 3 ½” outer diameter rod which has a 3” inner diameter mid-body and 2 ½” inner diameter thread ends. The rod ends are ½” wall thickness to 9” in length, while the mid-body is ¼” wall thickness, keeping the rod relatively light but extremely durable.

When you need the best and most efficient sonic tooling, look no further than Boart Longyear. High-quality precision steel plus special heat treatment processes provide unsurpassed stability, straightness, and durability of the sonic drill string assembly. Stringent manufacturing standards and ISO certification make sonic tooling from Boart Longyear the right choice for every sonic drilling project.

Contact your local Boart Longyear representative or distributor today.

Quality Policy:

Boart Longyear is committed to providing quality products, innovative solutions, exceptional service and value to our customers while meeting or exceeding all customers’ safety, environmental and regulatory requirements.

The Drilling Services Surface Coring drill crew used the powerful LF350e along with the new, patented XQ wireline coring rods featuring W-Wall, and the new Longyear diamond bits to successfully directionally drill at an angle of 65 degrees to the client’s required depth – which was almost 10,500 feet (3200 meters). An impressive feat in and of itself, the project had measurable productivity gains and proved the newest Boart Longyear rigs and tooling make a real difference in the field. 

With innovative features of the drill rig, combined with the deepest rated coring rods in the market and the fastest, smoothest cutting bits, the project’s success was also attributed to the talent, experience, and technical expertise of the crew.

Boart Longyear has combined proven technology from its most popular surface coring drill rigs to create the powerful LF350e.The forward tilting head design simplifies the rod handling process and reduces the need for operator intervention and maintenance. The rod breaking clamp is a hydraulic breaking device which means no wrench under power. The foot clamp rotates to break rod joints located between the foot clamp and rod breaking clamp. The rig also features a heated and air conditioned drillers cab to protect the operator from the elements and overhead hazards. Utilizing CAN bus communication and PLC programming, all LF350e functions are controlled electronically. The “e” in LF350e refers to the fully electronic control system. The rig is designed ergonomically to lessen fatigue and stress to the driller and helper. The LF350e has adjustable wireline speed to be able to set to lower the over shot and then pull the tube, which allows a hands-off safer approach. This is just one-way ergonomic design plays a part in reducing fatigue with this drill rig. The beauty of Boart Longyear’s business model of both contract drilling services and a drilling products business is access to immediate, direct, unfiltered feedback from drillers in the field. Drill rigs built for drillers.

A unique combination of -20 degree self-locking reverse flank angle on the threads and symmetrical load distribution when combined with W-Wall double-annealed mid-body, make XQ wireline coring rods some of the deepest rated coring rods in the market. XQ has an increased negative flank angle from of -20 degrees compared to -10 degrees in RQ rods. The increased negative flank angle combined with the double-start threads, nearly eliminate box bulging and provides greater strength in high torque applications.

Patented XQ joints have opposite double-start threads that are self-aligning so mating engages smoothly. This provides a balanced load response and double the contact area, which means half the contact pressure. This symmetrical load distribution increases load capacity significantly for stronger rods with deeper capacity. The lighter drill string increased drill rig depth capacity and reduced fatigue in driller's when manually tripping. The enlarged inner diameter also significantly reduced inner tube tripping time for improved productivity.

The new NXQ and HXQ W-Wall coring rods feature patent-pending, double-upset tubing, with the same overall weight reduction and faster wireline tripping speed as V-Wall. However, the standard wall thickness in the middle of XQ rod eliminates premature mid-body wear and resists bending, performing like straight wall tubing.

As all Boart Longyear coring rod, XQ W-Wall tubing is cold-drawn from high quality, North American alloy steel, uniquely processed to Boart Longyear specifications.

Boart Longyear has successfully created a chemical bond between diamond and matrix, which is stronger than the diamond itself. The increased diamond projection and improved face flushing create a bit with more versatility, higher penetration rates, and longer life. The Longyear Bits are similar to large diamond bits, but with the easy, smooth drilling characteristics drillers prefer. This means increased productivity throughout the entire operation, and ultimately more core.

To support higher penetration rates, the new Longyear formulas are combined with a new, more open, express geometry. Tapered intermediate waterways improve flushing and prevent accumulation of debris. Designed for fast cutting in competent ground, the new express geometry is available in our 16mm crown heights to maintain bit life at higher cutting speeds.

The unique Razorcut protrusions on the face of the bit contain diamonds that enable the bit to begin cutting right out of the box – even in the softest ground. The arrangement of these protrusions also improves the tracking and balance in the hole when drilling begins.

The most common practice, in this case, is to drive T45 or T38 rods for percussive drilling and API rods for rotary drilling. But when the customer was drilling with top hammers, his drillers had to change the complete tooling setup from API rods to percussive rods and vice versa. This proved to be ineffective and was burning resources on job sites and in tooling stock. The customer came to Boart Longyear for a rod solution that would be able to drill both rotary and percussive without changing the tooling set up.

Our engineers designed the new CBXP rods capable of both rotary and roto-percussive. By using the new rods, the customer reduced his spend on drill rods by 60% annually, purchasing one dual-purpose CBXP rod, instead of having to buy twice the number of rods for the two types of drilling. Productivity on job sites increased as changing tooling between the two different drilling applications was unnecessary.

CBXP drill rods are designed to be used as inner drill strings in double-head drilling applications. CBXP rods offer a more robust design than the common API rod and outperform API rods in durability and performance, especially when occasional percussive drilling is involved. It combines the effectiveness of an API rod but comes with more advantages than T38 and API rods, like:

• Higher flushing for higher penetration compared to API
• Longer thread life with an asymmetric thread profile
• Can be used for roto-percussive drilling (e.g. drilling though overburden boulders)
• Higher outside diameter compared to T38 & T45 rods results in higher flushing speed
• Conical thread shape provides better alignment for quick and easy make and brake
• Dual drilling capabilities as it can be used in both rotary and percussive applications

CBXP drill rods are primarily intended for use in rotary and rotary DTH drilling applications but are also commonly used as the inner drill string on double head rotary-rotary applications or in a single head rotary duplex application. CBXP may also be used for smaller percussive drilling applications. The rod ends of our CBXP rods are constructed of high tensile strength quench and tempered steel and are gas nitrided to provide additional life. Rod ends are friction welded onto mid-grade mid-body material. CBXP rods are manufactured in a variety of lengths and wall thickness. Boart Longyear can manufacture alternative rod lengths and spanner flats upon request.

Boart Longyear began manufacturing overburden and construction drilling products in 1989 at its facility in Germany to serve the foundation construction market. Boart Longyear overburden and construction tools were quickly recognized by the industry as reliable and well-designed. From the start, customers appreciated the use of high-quality steels, precise heat treating and thread gauging as well as the development of new tungsten carbides for the drill bit line. The attention to detail with the overburden and construction drilling tooling product line has made Boart Longyear one of the most respected names in the industry.

Today, Boart Longyear manufactures a broad offering of overburden and construction tooling at our 5000 m2 (54,000 ft2) facility in Eiterfeld, Germany. The modern ISO9001-certified facility hosts an array of advanced manufacturing capabilities including CNC (computer numerical control) machining, friction-welding, and induction hardening equipment for rod and casing products, as well as computer controlled ovens for assembly of tungsten carbide-tipped bits and tools.

Check out the full-line of Boart Longyear overburden and construction tooling by downloading the catalog.

In July, Vice President of Global Engineering Shayne Drivdahl discussed how Boart Longyear’s engineering team might be one of the company’s best-kept secrets. Providing a variety of professional drilling services to exploration and mining companies, the Company also designs, manufactures, and sells reliable drilling rigs, quality tooling, and accurate instrumentation.

Thanks to its team of engineers located throughout the world, the company is able to develop products and put them through rigorous testing in the hands of its own Drilling Services personnel. Tools and equipment are not only tested in the lab but also in the field. The collaboration between members of the global engineering team and Boart Longyear’s drillers elevates the performance of both Boart Longyear Drilling Products and Boart Longyear Drilling Services. Read the full article to learn more about the beneficial synergy gained between the two divisions.

In July, Design Engineer Anthony Lachance wrote about the newest developments and early testing results from the Roller Latch Overshot. Since Boart Longyear introduced the Q Wireline system in 1966, retrieving the inner tube from the core barrel has been handled the same way: an overshot with lifting dogs (spring loaded hooked “fingers”) is lowered or pumped into the hole until it snaps over a pivoting spearhead mechanism affixed to the inner tube assembly. Once the head assembly has been removed from the hole, the driller uses the pivoting spearhead to position the head assembly on their workspace and squeezes the back of the lifting dogs to release.

Since being introduced, this system has had the same basic issues. Learn how Boart Longyear’s new Roller Latch^TM Overshot has been highly anticipated and how drillers are noting the various positive developments: it’s easier to use, saves on wireline, and makes working with Q/P Roller Latch head assemblies much easier in difficult conditions.

In March, Global EHS Manager Brian Maeck introduced us to the Boart Longyear Glove Matrix. More and more mining and drilling companies are developing automation technologies to improve employee safety and efficiency. However, there are still plenty of risks for the hard-working hands of drillers: pinch points, sharp edges, rotating equipment, chemicals, etc. Hand injuries are still one of the most common and preventable injuries.

Along with following safe practices like using a risk assessment prior to any task, using the appropriate work gloves can dramatically reduce hand injuries. One solution, designed and developed to help employees select the correct glove for the task, is the Boart Longyear Glove Matrix. The Glove Matrix clearly sets the guidelines for what glove to use and when to use them. Read the article and download Boart Longyear’s Glove Matrix.

In August, Senior Engineer Andrew Salisbury wrote about the MDR500 rig’s success. This mobile underground diamond drill rig was designed exclusively for Boart Longyear Drilling Services. It leverages the upcoming LMi power and control interface and comes equipped with 500m of on-board rod storage (NQ rods) making it a self-sufficient mobile drill rig.

The MDR500 was the long-term brainchild of Geoff Moroney (Drilling Services Asia Pacific Fleet & Asset Manager) and John Kirkwood (Drilling Services Asia Pacific Regional Director). The project was given the go-ahead in the third quarter of 2016 aftermarket research indicated that there was a desire from sections of the Australian market for a medium depth underground diamond drill rig which was in the most part self-sufficient and could move quickly from hole to hole.

In this article, Anthony Markham, Senior Product Designer of Capital Equipment, describes the challenge Boart Longyear’s Drilling Services faced with moving existing StopeMaster equipment safely and quickly through a mine. With the combined dedication of many remarkable Boart Longyear employees around the world, the team started engineering a new StopeMaster MDR rig that would solve the issues the mining company was experiencing.

The newly commissioned StopeMaster MDR rig solved the issues of moving the StopeMaster, making moves from stope to stope faster and requiring less time and resources from the mine. The StopeMaster MDR equipment is also safer with rod handling capabilities and semi-autonomous drilling with a new LMi control panel which controls both the rod handler and the StopeMaster MDR rig. Check out this article and download the Drilling Services Overview to learn more about Boart Longyear Drilling Services capabilities, fleet, safety programs, and drilling methods and applications.

Is a career in drilling right for you? In this article, the challenges of drilling are discussed, and key factors are considered when researching jobs in the drilling and mining industry. For example, at drill sites, a certain level of physical fitness is required for employees to adequately carry out their tasks. Working on a drill rig involves labor-intensive activities such as heavy lifting and manual handling.

A career in drilling is an important decision for both employees and their families. Individuals who work in drilling enjoy work that is often physically demanding in challenging conditions. But they’re also aware of the great benefits and rewards of this industry. If a career in drilling seems like a good fit for you, this article is a must-read.

In June, Global Product Manager Zac Strauss discussed the most important factors when considering a new drill rig purchase. Buying a new drill rig is a big decision and many variables and factors affect that decision. The biggest question one has to answer is, “Will this drill rig make money? Or cost more to own than some other option that can accomplish the same for less?”

It’s important to take time to consider options. Evaluate current drill rig fleet and consider what it will take to get everything maintained and updated to be competitive. Does your drilling rig take advantage of recent innovations and meet the latest safety standards? If repairs and available parts outweigh returns, look at updating your fleet. The number one reason to buy new equipment versus used equipment is to enhance productivity, improve safety, and enjoy long-term reliability.

Since 1890, Boart Longyear has been transforming the drilling industry with innovations like the wireline for faster core retrieval, dual-tube flooded reverse circulation drilling, and sonic drilling for mining applications. This article focuses on the LR500, a drill rig built specifically to meet the increasing needs for deeper dewatering wells for Nevada mining.

Check out this article to discover the distinct features of the LR500 such as the size and weight of the casing, how it’s electrically powered, and its automated drilling features. Also be sure to download the Drilling Services fleet depth chart to discover the wide range of services Boart Longyear provides.

In February, Chris Lambert, Senior Product Manager, discusses different factors that affect the way drilling could be affecting bits. The best way to save money on consumables like bits is to check drilling methods. In this article, these simple tips could decrease operating costs and add more cash to the bottom line.

Quick tips are also included, which give insight into rotational speed, weight on bits, torque, penetration rate, water flow, and sharpening. You can also download the Diamond Products Catalog to explore the full range of diamond bits Boart Longyear offers.

John Roberts, Professional Geologist and Commercial Manager for Boart Longyear, describes the complexities of designing and planning a drilling project. There are many risk factors which need to be considered in order to mitigate issues that could impact productivity and/or budget, ultimately impeding the success of the project.

This article addresses considerations and common pitfalls in drill pad planning, which is critical to the mobilization of the drills and crews that will complete your carefully designed drilling project. The first thoughts should be “what purpose is the hole, and what type of drilling will be performed.” Make sure to download the recommended drill pad layouts!

As we move into 2019, you can look forward to additional case studies, interesting and complex drilling projects, tips and tricks, and how-to articles. We are working hard to bring you the content that makes a difference and makes your life a little easier. Thank you for reading INSITE and engaging with Boart Longyear. We couldn’t do any of it without all of you! Wishing all of you a successful and prosperous 2019!

If you have any questions or feedback, we would love to hear from you! You can leave comments below by clicking to expand on the icon and word DISCUSSION.

When the right drill bit is in the right ground operated under the right conditions, more core ends up in the box at the end of a shift. There isn’t a perfect drill bit matrix or geometry that cuts every ground as quickly as possible. A Longyear bit may cut 17 inches per minute in Arizona, but cut just three inches per minute in Ontario.

Although diamond drill bit selection is often an afterthought, it’s just as important as drillers deciding how much water/mud to run or how fast to spin rods.

There are many factors to consider when selecting a drill bit, including the main objective of a project. As mentioned, the overarching objective is always more core in the box, but there are additional elements that need to be considered. For example, a rod trip takes significantly less time at 400 feet than a rod trip at 4,000 feet. While bit life is important, it’s less crucial at the top of a hole because that usually means sacrificing penetration rates.

In Australia, a site used two different bits at different depths. A Longyear Red Express bit was used to cut 60 centimeters per meter with a life of only 120 meters at the top of the hole. Once that bit was done they switched to a Longyear Yellow Stage 3, because rod tripping took too long. With this bit they only cut at 35 centimeters per minute but achieved a life of 300 meters per bit. Using a singular Longyear bit, this site put 6% more core in the box than they did with a competitor’s bit. However, using these two Longyear bits in tandem, they saw a 23% increase of core in the box over the competitor’s product. Sometimes, it’s more beneficial to cut faster even if it means tripping more.

Once a driller decides whether the objective is cutting faster or tripping less often, next it’s important to establish how hard the ground is to cut. Contrary to popular belief, the ground drillers cut is (probably) not the hardest ground on earth. This is where the Mohs scale comes into play. The Mohs scale is an exponential scale from 1 to 10 to quantify mineral hardness. Minerals with a higher Mohs hardness will scratch anything with a lower Mohs hardness. For example, a mineral classified as a four will scratch a three but not a five.

All the bits offered on the market today are targeting a specific range of the Mohs scale for the best performance. To determine the Mohs hardness of the rock to be drilled, a Mohs hardness scratch test kit is needed. This kit is a series of picks made of different materials that, when used properly, can determine the Mohs hardness plus or minus 0.5.

The Boart Longyear scratch test kit has four scratchers with eight replaceable tips and a sharpening stone. If the numbered tip scratches the rock, the rock is softer than the number on the tip. If a seven scratches and a six doesn’t, you know you’re in 6.5 rock. You would then select the bit created for that rock.

Once ground hardness is identified, Boart Longyear offers a Longyear Diamond Bits Hardness Rating & Comparison Chart to find a recommended bit for that ground. For example, Purple is meant for 1 - 4.5 rock, up to Red which is best for 7.5 – 9. Purple covers such a large range numerically because the Mohs scale is exponential (1 and 4.5 on the Mohs scale are closer together on “true” hardness than 7.5 and 9).

In the cross reference above, bit range overlaps, and the bars representing each drill bit are quite long. This is where the objectives of the site come into play. For example, if you are in a 6.5 rock, select a Green Bit or a Yellow Bit. Which one should you try first? It depends. If the site is cutting a lot of short holes and bit life isn’t a big concern, you would likely have the best luck with Yellow – it would penetrate faster than Green, but not have as long of life in 6.5 rock. On the flip side, if bit life is a concern because you’re drilling deep holes, you may prefer Green.

Another thing to consider for bit selection is geometry. While the Green bit is, in general, tougher than the Yellow, a Green bit with more open area and a Yellow with less open area will exhibit very similar cutting characteristics.

The geometries offered by Boart Longyear are all designed to cut a little differently. Within each color bar, the Express has the ability to cut harder rock than the Stage and the Stage will cut harder rock than the Tapered Waterway. This is a result of what is called, “open area”.

Open area is determined by finding the surface area of a disc with the same outside diameter and inside diameter as the drill bit, and subtracting the surface area of the drill bit with all the waterways cut in. What’s left is the area of the waterways, flutes, and rounds, and the percentage of this number compared to the area of the total disc is the open area. Express has an open area of 30%, Tapered Waterway has an open area of 25% and Stage has an open area of 20%.

Standard Waterways

• Most common waterway style
• Longest life based on lowest open area 15%

Tapered Waterways

• Pushes cuttings to the OD and reduces pressure across bit face
• Open area 25%
• Preferred

Express Waterways

• Faster penetration and/or lower weight
• Open area 30%
• Free-cutting formulas

Stage/GT

• Wide waterways, more versatile
• Better flushing and penetration than standard waterways
• Open area 20% for Stage

Deep ID Waterways

• Recommended for lost circulation applications; prevents the lifter case pulling into the bit and shutting off water
• Can be used instead of face discharge in triple-tube and piloted core lifter case
• Face Discharge preferred for core recovery. Open area based on waterway

Face Discharge Waterways

• Reduces water pressure on the core and redirects fluid to the face of the bit (reduces washing core material), aiding in core recovery
• Required for piloted core lifter cases
• Open area based on waterway

If cutting at the top range of these bars, more open area will be needed, and the Express, for the middle and bottom ranges, will use Tapered Waterway or Stage, respectively.

The Longyear Yellow and the Longyear Green bits overlap substantially in the cross reference. This shows either the Longyear Yellow or the Longyear Green can cut Mohs 7 rock. To cut this Mohs 7 quickly, a Yellow Tapered Waterway bit will be needed. To cut it more slowly and optimize bit life, a Green Stage bit should be used. A Green Express, a Green Tapered Waterway and a Yellow Stage would land somewhere in-between.

Once a bit has been selected for the rock type, crown height, and geometry, the last step is to collect data and test the chosen bit’s performance.

Once the ideal bit has been identified – it needs to be tested, and the only way to make an informed decision during testing is to collect data.

Here are three mandatory data points to collect:

• Penetration rate on every run
• Mohs hardness every run
• Bit life of every bit

Once the data has been collected, this information can be used to either validate the choice initially made or adapt based on unaccounted circumstances. For example, if the Green Stage bit was selected but the penetration rate wasn’t as high as expected, then the Green Express and the Yellow Stage would be good bits to try next. The Yellow Stage may not provide the desired life, but the Green Express may be a perfect in-between. All this shows in the data and at the end of the day more core ends up in the box.

With a combination of knowledge, the right tools, and good planning, every shift can be optimized, and subsequently, put as much core in the box as possible.

Learn more about bit optimization and the productivity results from the field - New Longyear Bits Put 23% More Core in the Box

Ready to start testing? Contact your local Boart Longyear representative or visit My Drill Store.