Drill Bit Extension

Drill bit extensions reduce force at the shoulder and minimizes strain of the arms when drilling overhead.



The drill bit extension is an engineering control that can help reduce musculoskeletal disorders (MSDs) due to overhead work. Drill bit extensions can be attached to a standard drill or screw gun allowing a worker to hold the tool below the shoulder and closer to the waist. This reduces force at the shoulder and minimizes strain of the arms when drilling overhead.

A drill bit extension is made by welding a standard socket to a steel rod or tube. A drill bit is welded to the other end of the steel rod or tube, so the extended drill bit can be inserted into a drill or screw gun chuck.  PVC pipe is placed over the extension as a sleeve to protect the worker’s hand from the spinning shaft. The PVC sleeve also provides better control of the tool.  Workers hold the power tool with one hand and the sleeve with the other (figure 1).
Figure 1.  Drill bit extension. Milwaukee bit extension (Photo courtesy of Milwaukee Tool)
Drill bit extensions are available in many different lengths and diameters (figure 2).  Lengths generally run from 12 to 40 inches.  It is also possible to make your own extension.  Before using an extension for drilling or fastening, it should be determined whether it is appropriate for the job.

Figure 2.  Example of a Milwaukee drill bit extension (Photo courtesy of Milwaukee Tool)

Figure 3. Example of a Greenlee drill bit extension (Photo courtesy of Greenlee Tools, Inc.)

Risks Addressed:

Overhead drilling can cause musculoskeletal disorders (MSDs) such as shoulder muscle strains; tendonitis, which is inflammation of the tendons; or rotator cuff tears, which is a rupture of a shoulder tendon.  The drill bit extension can help reduce overhead work by allowing the hands to be near the waist and the arms next to the body while drilling overhead.


How Risks are Reduced:

A drill bit extension reduces overhead work by allowing the worker to keep their arms below their shoulders and the drill near their waist.  Workers are less fatigued when they do not have to hold a heavy drill above their shoulders for long periods of time.
Independent studies have shown that working overhead increases the incidence of injury to the shoulder, arms, neck, and back. Safety and health experts agree that reducing the vertical and/or horizontal distance that the tool is away from the body lessens the stress on worker’s shoulders and arms.  Using an extended drill bit also eliminates the need for ladders and step stools. Most drilling tasks can be accomplished while standing on the ground. The risk of falling is decreased or eliminated.
Manufacturers report that the extension is easy to use after a little practice.  The extension does not add significant weight of the drill, as it weighs less than 2 lbs. Anecdotal evidence from workers who have used drill bit extensions confirms that there is less strain on the shoulder.

Effects on Productivity:

Extended drill bits increase productivity by decreasing the time to accomplish drilling tasks.

Additional Considerations:

You can make your own bit extension, which will cost $1–2 for materials plus your time. Manufactured bit extensions cost from approximately $12 for a 12-inch model to $45 for a 24-inch model.
For safety, make sure you push the extension onto the drill chuck tightly, before you turn on the power.  In a screw gun, the screw must also be tight in the bit.
A drill bit extension does not prevent the neck from being bent back while drilling overhead. Workers shoulder be instructed to change stressful neck positions frequently. Alternately, job rotation has been used at many worksites to minimize exposure to excessive backward bending of the neck.  
Workers should always wear safety goggles when using an extended drill bit due to falling debris from the drill hole.
There are also drills with extended handles that be used for both overhead work and in bent postures.  While these drills are more expensive than the drill bit extension, they are likely useful when workers are doing this type of work over an longer timeframe, especially for bent postures.  Please see this solution sheet, Standing Fastening Tool, for more information.


Dan Anton, PT, PhD, ATC, Cassie Malecha, DPT, and Neil Morris, SPT – Eastern Washington University

Hazards Addressed:


Greenlee Tools, Inc.
To obtain information, visit www.greenlee.com or contact 1-800-435-0786 grncustomerservice@emerson.com

Milwaukee Electric Tool Co.
To obtain information, visit www.milwaukeetool.com or contact 1-800-729-3878 http://www.milwaukeetool.com/contact

Irwin Tools
To obtain information, visit www.irwin.com or contact 1-800-464-7946 http://www.irwin.com/about-us/contact-us

Return on Investment

To calculate the return on investment (ROI) for your specific application, please visit our Return on Investment Calculator. While a specific ROI example has not been developed for this particular solution, the ROI Calculator provides a useful tool and guidance on how to generate your own on investment analysis.