So many threads, so little information. Every OEM drill rig has a different thread. There are threads for drill rods…threads for Quick-Disconnects…threads for bolts. Trying to get a replacement part without a clear understanding of how to determine the right type of thread can cause you to order a part you can’t even use.   Getting the right thread is a big deal. Not using threads that are 100% accurate can wipe out all the threading on your rig: your pipe, tooling, adapters, etc. If any of these measurements are incorrect, you risk breaking connections or being unable to connect tools. Same if you use a worn thread with a new thread. Since drill pipe is constantly being threaded and unthreaded, if you don’t replace the whole string when a section is worn out, your threads may not shoulder up correctly. This can cause your tooling to snap off.   Luckily, aftermarket HDD tooling experts stay on top of evolving thread patterns and manufacture a complete line of adapters and tools with a wide range of threads for HDD rigs of all types.  

Why Are There So Many Variables?

In an effort to improve manufacturing (or maintain their stronghold on the supply chain, depending on who you ask), OEMs are constantly revising the threads on their rigs and HDD tooling equipment. Some even patent their thread patterns, making it extremely difficult for drillers to get a quick replacement tool with the right thread without going directly to the manufacturer. Don’t assume that all models are the same, either. OEMs also change thread types between years on the exact same rig models. This can make interchanging your tools a nightmare.  

Note the fine threading on the left side of this adapter and the coarse threads on the right.


How to Get the Right Thread from Your HDD Tooling Distributor

  Send as much information as possible and let your distributor help you sort out what you need. HDD tooling experts understand how important it is for you to get a tool you can put to use immediately. We know that every minute you spend on the phone and not drilling is a minute you’re losing money. Your best bet is to send your HDD tooling supplier a picture of the thread you need with some accompanying dimensions.  

Here’s what to do:


  • Put a measuring tape next to the bolt for scale and take a clear photo of the side of the pin (male end). This helps identify the shape of the thread, called the “thread profile.”
  • Next, measure the length of the thread (using the pin/male side) from shoulder to end.
  • If it is a tapered thread (i.e. bigger up by the shoulder and smaller at the nose), also measure the outer-diameter at the big end and the outer-diameter at the small end.
  • Count how many threads there are in one inch to determine the pitch (TPI).
  • Give these dimensions to your distributor.
  • Finally, if you have it handy, let your supplier know the year, make and model of your drill rig and where the thread is used (drill rod, quick-disconnect, blade bolt, etc.)

  These measurements will likely be enough to determine the thread type. If you’re still not sure, ask your HDD tooling manufacturer for their input.  At Melfred Borzall, we can send out a thread reference tool to help you match your thread by comparing it to a series of pictures.  

Supply your distributor with measurements for the larger diameter (A), smaller diameter (B) and

length (C). Count the number of threads in your bolt. Your distributor can help determine the TPI.

  Remember, you don’t have to figure this out on your own, your HDD tooling supplier is there to help and give advice. If you have an older or obscure model rig or tool, most HDD tooling manufacturers can fabricate a custom adapter for you right away. Melfred Borzall’s FastAdapt program uses your measurements to create an adapter on the spot. We can usually ship it out the same day you request it, depending on the time we receive your call.   The best way to make sure you get what you need is to be prepared with as much information as possible before you get on the phone with your supplier. This can save lots of time on back-and-forth.   If you have any questions, call the HDD tooling experts at Melfred Borzall to talk threads. Or start a live chat at We can’t get enough of this stuff.