Application Tips: Directional drills
| May 28, 2009
With all the machine options available to contractors, choosing a directional drill can be tricky. Factors to consider include size of work area, the type of work being done, the size of bore needed and the type of soil the crew will encounter on the jobsite.
Directional drills are used in various applications from burying cable from the curb to a house, to installing a larger-diameter product over several thousand feet.
The type and size of jobs you usually do will dictate the directional drill you choose, says Richard Levings, senior product manager for HDD equipment at Ditch Witch.
“Contractors typically own machines in the 20,000- to 30,000-pound range because they can do both smaller jobs and the occasional larger jobs,” Levings says. “If they are doing various utility jobs, however, they may have to use something more universal.”
According to Gaylord Richie, territory manager for Astec Undergound, all directional drills do the same things: push, pull, turn and pump. Most drills are rated by pullback, and contractors should choose a machine based on the length of the bore and the diameter and type of product being installed.
Directional drills can work without damaging the topsoil or ground, making them a popular choice for work in residential yards, marshes and wetlands. The operator also has the ability to steer the machine, making it easier to avoid existing utilities underground.
“Directional drilling is still in its infancy, but every year the machines improve and you can use them for any type of underground installation in any type of soil,” Richie says.
Getting an extra edge
The most important aspect of selecting a directional drill is determining what type of work will be done.
“So many have gotten into this business and been successful,” Levings concludes, “But a lot more have failed because they didn’t do their research and didn’t have a business plan.”
To establish and maintain a profitable business, understand what you want to achieve, Richie says. “Then get a drill that is going to efficiently do that.”
As for a business plan, it is important to know the industry you are getting into, the various needs of the industry (i.e. cable, electric) in your area, how many people you are going to need and how fast you expect or want to grow.
According to Ed Savage, trenchless segment manager for Vermeer, power-to-size ratio and getting the most torque should be considered when selecting a directional drill.
“When doing urban projects, it is important to have a small machine so you can easily access backyards and congested areas,” Savage says. “The machine’s power is still important because it relates to how quickly you can get the bore done. In rural settings, machine size might not be as big of an issue, but you want more power in the machine to accomplish longer bores.”
While smaller drills costs less money, they won’t do the job in every soil condition.
Potential buyers need to talk to contractors in their area who have been successful and know what works. “Research the products, know what type of soil you’ll be dealing with and let that guide you more than size because sometimes size will get you in serious trouble,” Levings says.
Richie says there are three things to consider when spec’ing a directional drill: What do you want to do with the machine? How much power is needed to pull the product in the ground? What rotary torque is needed based on the type of ground material? “You need to know that so you can go to the dealer and say, ‘This is what I’m looking for.’”
Don Cary, president of StraightLine, says a rarely discussed key feature of directional drills is operator visibility of all drilling functions. “Ideally, the operator should be able to see the spindle when the carriage is retracted for easier pipe changes, the rod loader during pipe changes and the positioning of the tool joints in the wrenches,” he says.
Tooling and added features
Tooling is an integral part of the drill selection process. “You can have the most powerful machine, and if you don’t have the proper tools, you can’t cut a hole,” Richie says.
Ditch Witch’s Web-based Downhole Tool Selector will suggest the proper tooling needed based on the information you provide. Select either bit or backreamer, choose one of seven types of soil and the machine model. There are different styles of bits to use for the pilot bore, Levings adds, including back reamer and swivel types that are dependent on what type of soil you are working in.
According to Savage, on the small drills, make sure you have a 6-foot drill stem to reduce the amount of time operators spend making and breaking drill stem joints. On the mid-sized drills, consider Vermeer’s AutoDrill, which allows you to set a boring or pullback speed, after which the machine will automatically maintain the speed.
For hard rock drilling, Astec Underground manufactures an air hammer system that can drill through 34 psi of granite. It cuts the cost down and makes less of a mess, Richie says. The tool marries up to most brands of directional drills. Vermeer offers the Rock Adaptable Terrain Tool which will bore in conditions including solid rock, cobble, clay, sand, hard pan and dirt. It does not require special drill stems or gearboxes to drive it.
Where there’s drilling action, drilling fluid will be needed. StraightLine offers a Web-based drilling fluid guide that explains everything from the complexities of different types of soil and various boring methods to drilling fluid components and tips on how to choose the right fluid for your job. Check out the guide at this site.
For help planning your drilling strategy, Vermeer offers Atlas Bore Planner software. It can be used on any desktop, handheld or laptop computer running Windows 95, Windows 98, Windows NT, Windows 2000, Windows ME or Windows XP and is available in eight languages. Its features include:
- generation of proposed rod-by-rod plan for the operator to follow
- topography, utilities and bore-planning targets can be entered or moved
- warns if the bore path plan exceeds the drill stem or product minimum bend radius
- enter at least one target point and the software can create an entry and exit point.
Performance, serviceability and safety
In addition to building new machines StraightLine refurbishes and remarkets used drills. StraightLine processed more than 330 used drills in the past five years, a process Cary says has led the company to discover the most important features of a directional drill.
“It involves reliability, good component selection, hydraulic and electrical designs that are easy for the contractor to diagnose and repair, and finally, parts that are easy for the contractor to obtain,” he says.
Cary says that most contractors can rely on their experienced staff to choose a machine that ensures maximum performance on the jobsite. He also recommends talking with operators of the specific models being considered.
“The two things we strive for are performance and reliability,” Levings says. “We typically use a lot of horsepower and we balance the loads to the available horsepower. Our operators, contractors and owners can see efficiency on their jobsites.”
With most manufacturers, if there are surprise or routine maintenance issues the machine can be taken to a local dealer or a dealer representative can come to the jobsite. According to Richie, contractors should ask themselves, “Can I do it on my own, or is it something that I have to take to the dealer to get fixed?”
All Astec Underground directional drills feature “life jackets” in case the machine goes down. A manual control allows an override of the microprocessor, enabling the operator to continue his work until he can get the machine fixed. “Computers make machines more efficient, but they can break down” Richie says. “We give them a greater comfort level with the life jacket.”
Other standard Astec offerings include side lockout and zap alert. According to Richie, Astec was the first to manufacture side lockout. This feature enables the locator to shut down the machine if he loses sight of the operator. To reactivate the machine, the operator and the locator must reset the machine together. With zap alert, if an electrical line is hit, zap alert is activated, complete with flashing lights and a siren, to let the operator know that the drill is hot. The siren turns off when the machine is no longer energized.
What type of drill is right for you?
The smallest directional drills have 10,000 pounds pullback and below. They are best used for service connections, street crossings, down-the-block residential or commercial applications and small-diameter products.
With machines in the 10,000- to 20,000-pound pullback class, contractors are able to place a variety of lines in soil, including fiber, copper and coaxial, as well as cable, gas and other utility applications.
Contractors use drills larger than 20,000 pounds pullback for longer applications – 400 to 800 feet – doing underground water, electrical and gas work.
“In this class, we have two all-terrain units that allow us to work in all soil conditions – hard rock, soft rock, broken rock and soil,” says Ditch Witch’s Richard Levings. “They are unique to the industry and are effective because they allow you to do big jobs with a compact unit.”
Contractors need to understand the work they’re going after, says Astec Underground’s Gaylord Richie. “Anything 100,000 pounds and higher, you’re getting into a specialized niche, highly technical part of the business.”
Want additional information? Vermeer’s “Fundamentals of Horizontal Drilling” is a comprehensive guide in English and Spanish that provides basic knowledge for those working with or around horizontal directional drilling equipment. Customers may receive a copy of the book from their local dealer.