What size Borescope Do I need?

Shopping for a borescope? First, determine what borescope size is best for you. This guide will walk you through your options and help you make the right decision.

If you’re in the market for a visual inspection tool, you may be wondering what size of borescope is right for you.

From airplane engines to intricate plumbing, borescope inspection cameras are used to examine a variety of machinery. With such versatility, it’s no surprise there’s a wide range of borescope sizes available.

For some inspections, a borescope 2mm in diameter (or smaller) is required to peer into machinery. However, when the inspection area is roomier, many maintenance professionals opt for a larger borescope. According to Quality Magazine, “durability and image quality increase with thicker diameter and shorter length insertion tubes.” Adopt this line of thinking and you’ll conduct more accurate inspections.  

Clearly, it’s essential to match the size of your borescope to your inspection job. In this article, we’ll cover the most common borescope sizes available and what they’re typically used for, so you can get a sense of which inspection camera is right for you.

Micro Borescopes

Micro borescopes are inspection cameras typically 0.37mm to 0.7omm in diameter. These tools are used to navigate and inspect the most narrow entry points and passages in a wide variety of machinery.

The micro borescope does not feature articulation, meaning it offers only a straight view during inspection. Some micro borescopes, however, are equipped with flexible rods. These micro fiberscopes use high-quality fiber bundles to maneuver around small and complex structures.

Those who prefer a rigid borescope can also consider a side-viewing scope, which uses a camera fixed at a certain angle. However, most maintenance professionals find the standard tiny borescope, which provides a 70 degree field of view, offers an adequate view of the inspection area.

The small size of mini borescope makes them popular in the aviation and industrial fields. Aviation professionals use these inspection cameras to examine the internal engine’s most secluded components, including the internal rotating sections and combustion chambers. Similarly, those in the industrial field use micro borescopes to examine combustion engines and steam and gas turbines. 

3mm And 4mm Borescopes

3mm borescopes are popular across many industries because of their small size and the wide variety of features they offer. It’s important to note that while these inspection cameras are often listed as 3mm borescopes, they can range from 2mm to 3.9mm in diameter.

3mm borescopes are generally small enough to fit into narrow passages. When borescope size alone is not enough, opt for a two-way or four-way articulating device, which allows for better maneuverability within the inspection area.  3mm borescopes are popular for aerospace, machining and casting inspections as well as inspections in the field. They are typically used to examine engines, small diameter tubes and to see inside walls.

Only one millimeter wider, the 4mm borescope performs many of the same functions as the 3mm camera. These inspection cameras range from 3.7mm to 4.5mm in diameter and are popular among aerospace technicians for turbine blade inspections. Articulating 4mm borescopes are also especially popular among casting and manufacturing professionals for their ability to navigate tight corners and bends.

6mm and 8mm Borescopes

The 6mm borescope is a popular borescope size among maintenance professionals of  many industries. This device is used by the aviation, power generation and even the pharmaceutical industries for equipment inspection and more. Although advertised as 6mm in diameter, the size of this engine borescope can vary between 5.1mm and 6.7mm in diameter.

Technicians conducting straightforward examinations should consider a rigid 6mm borescope inspection camera. These devices can adequately perform simple inspections and are a cost-effective option. When complex inspections require a rigid borescope, opt for an articulating camera. Two-way and four-way articulation will expand your field of view and allow you to inspect any pipe or equipment, no matter the angle. 

If a rigid borescope is insufficient, try a 6mm fiberscope. In the aviation industry, technicians favor these tools for extensive inspections of rotating turbines, transmissions and the airframe. Keep in mind, image quality may be lacking. According to POWER, “in years past, flexible fiberoptic scopes were the industry standard. However, because of the nature of fiberoptics, image quality was not nearly as good as today’s video borescopes.” Try a flexible videoscope if your inspection job requires more detailed imaging.

Only 2 millimeters wider, the 8mm borescope, like it’s 6mm counterpart, is versatile and used by many maintenance professionals across several industries. This size borescope can be used for automotive inspections, parts assembly and HVAC inspections. A portable borescope of this size is also suited for aircraft and helicopter turbine inspections as well as other forms of in the field servicing.

If you don’t anticipate examining particularly small, narrow machinery, the 6mm borescope and the 8mm borescope are a great choice. Both devices will provide excellent image quality due to their larger size, meaning you’ll conduct more accurate inspections. With this borescope size, you’ll enjoy versatility. According to ZDNet, borescopes “are super-handy, and once you get one, you’re continually finding new uses for it.”

10mm Borescopes

At 10mm in diameter, this size borescope is about as large as they come. Built for durability, 10mm borescopes are generally used in hostile environments. It’s no wonder these tools are suited for manufacturing!

10mm borescopes are available only as rigid borescopes. While unable to conduct complex inspections, this borescope size does offer excellent image quality thanks to their size and use of glass rod lenses, as opposed to fiber optics or cameras.

Image quality can, however, vary from tool to tool. This size borescope offers focusing and non focusing eyepieces. At USA Borescopes, we recommend technicians anticipating frequent use and recurring damage to their borescope opt for the non focusing eyepiece, such as those working at a casting house. Lab professionals, for example, who require detailed inspections should splurge on the focusing eyepiece.

10mm rigid borescopes, however, are among the most cost effective inspection devices. These tools are cheaper and require fewer repairs (their enclosed design makes them water, dust, oil and diesel proof) than other, more complicated devices. Although many end users are looking for a cheap borescope.

Custom Borescopes

If USA Borescopes doesn’t offer exactly what you’re looking for, we’re happy to create it for you!

For customers dealing with a unique inspection, consider building a custom borescope. Select your ideal borescope size, then choose a custom length that suits your needs. Is the environment you’re examining particularly narrow? Customize your micro borescope to have the exact angle of view needed for your inspection.

Nothing is out of reach when you choose a custom borescope.

Contact Us

With a great number of borescope sizes to choose from, it may feel difficult to make a selection. If you’re having trouble determining which size borescope is right for your inspection job, don’t hesitate to contact us. Our staff of seasoned technicians is happy to walk you through our video inspection cameras and answer questions about our custom borescopes.