When drilling your pilot shot, it’s tempting to throw the biggest, baddest bit in your toolshed onto your drill and call it a day. Inexact tooling choices might get the job done eventually—but will hamper productivity and expose your HDD tools to unnecessary wear and tear.
Knowing what to look for before you begin drilling and familiarizing yourself with some of the key differences between bits will help you choose the best tool for the job. Here’s what you need to know.
Knowing the diameter and quantity of the pipe you’re installing is the first step in selecting the best bit for the job. Keep this knowledge in mind as you walk the path you’re planning to shoot. As you look at the depth and location of various other utility packages, evaluate the thickness of your own product and whether you’ll have the ability to weave through existing utilities or will have to circumvent them with sufficient clearance on all sides. Your goal is to drill a hole with the minimum diameter that will enable you to successfully pull product without squeezing or stretching the pipe.
It’s impossible to know exactly what type of soil you’ll run into during your job, but it is possible to get a pretty good idea before you begin. Inspect the soil in your entry pit and receiving pits. By physically handling the dirt, you’ll get a sense of the layers of material that are running through your bore path. Of course, with all HDD jobs, there will be surprises, but having a pretty good idea upfront of the type of material you’ll be drilling will help you select the bit that will work best.
Here are the types of bits you should use in each soil type:
Sand – Sand drilling requires a pointed bit with protective carbide buttons that help you snake your way through abrasive conditions. Because there’s less surface area to push off, direction changes might take a little longer. However, a bit with a wider front—one like Excalibur—can help mitigate steering issues.
Shale – To penetrate shale, a bit needs to break up the material and successfully move it out of the way, so a bit with sharp teeth performs ideally in these conditions. Look for a bit with removable carbide cutters to get more life out of your HDD tools. A bit like the Eagle Claw SD often ends up being the best bang for your buck. Your initial investment may be much greater than buying a typical aggressive bit, but once you realize you will wear out ten or more of those other bits before needing to rebuild your Eagle Claw SD, the decision becomes obvious.
Clay – If it’s a softer clay, you’ll usually want a blade that has a wide surface area to help with steering. A harder or compact clay will require a bit with more of a point. Carbides aren’t a necessity, but it doesn’t hurt to have their extra protection.
Cobble – Drilling cobble is more about moving smaller pieces of material out of the way than it is about boring through a hard rock surface. The general rule when selecting a cobble bit is to look for a tool with dome cutters which will roll off the rocks. Trying to bust through the material will just create unnecessary wear. This is because bits with teeth extending out from their face, or those with more of a point, will tend to hang up on the cobbles or snap off all together.
Hardpan & gravel – In these challenging conditions, you’ll need a rounded bit that can chew through the material but has enough surface area to facilitate direction changes without slowing down. Look for blades with a round nose and aggressive front and side cutters. Rock Saw is a perfect example of the type blade that can handle the job.
Rock – For drillable rock, you’ll want an aggressive bit with a steep taper that helps with steering. Our appropriately-named Steep Taper Ultra Bit 3 features conical carbide cutters that work relentlessly on the rock to carve out a clean-cut path.
We’re always looking to make things easier and more efficient for drillers. Lots of R&D goes into adjusting the specs and features of HDD bits to improve their performance. For us, the star of our HDD tooling fleet is our newest blade, the Red Diamond.
Red Diamond is an ideal all-around bit that will take on any soil in its path—it’s like driving a tank underground. Though Red Diamond can stand up to abrasive material like sand, it’s better to save this bit for conditions in which standard blades might struggle. Designed with solid carbide as protective armor on all sides, this steep tapered blade can out-drill and outlast pretty much every other blade on the market. This longevity isn’t great for sales, but it is great for drillers.
Bit choice is a big deal. Knowing your bore path before you begin will help you choose a bit that will give you the best shot at success. Invest in blades that are designed to handle the types of soil and clearance requirements you encounter most often. Having the right bit at the ready is a smarter, faster way to work.
Have a question about which bit is best for your job? Our expert HDD tooling distributors are here to help.