What is a bit reamer?

What Is a Bit Reamer?

A bit reamer is a precision rotary cutting tool used to enlarge and refine a pre-drilled hole to its final size. It ensures a perfectly round shape and a smooth surface finish while maintaining tight dimensional tolerances. Unlike a drill bit, a reamer bit is not used to create a hole from scratch. Instead, it follows an existing hole, removing only a small amount of material to correct imperfections and achieve the final specification. Reamers fall under the broader category of reaming tools, which are essential for achieving high-precision results in industries like aerospace, automotive, and precision engineering.

Used across aerospace, automotive, and general engineering industries, bit reamers and Reaming Tools are essential for high-performance projects where accuracy, repeatability, and finish quality are non-negotiable.

How Is a Bit Reamer Different from a Drill Bit?

While a drill bit is designed to create a new hole by removing material quickly, a bit reamer is used to improve and finalise the quality of that hole. It removes only a small amount of material (often as little as 0.001 inches or 0.01 mm) to bring the hole to its precise final diameter. It also enhances the roundness, straightness, and surface texture of the hole, helping ensure components fit correctly and perform as expected. This makes Reaming drilling tools ideal for hole cleaning and preparing bores for assembly.

Key Characteristics of Bit Reamers

• Finishing Tool
  Reamers are designed to complete the final stage of hole preparation. They produce an accurate diameter and a superior surface finish, often reducing the need for further operations.
• Minimal Material Removal
  A reamer cuts a fine layer of material from the inside of an existing hole. This precise action helps avoid distortion, improve roundness, and enhance the bore quality.
• Follows an Existing Hole
  A reamer relies on a pilot hole, usually drilled slightly undersized, and follows that path without drifting. This ensures the hole remains properly aligned and concentric, even at total depth.
  

Types of Reamer Bits

Bit reamers are available in various configurations depending on the specific application and desired hole geometry:

• Straight Reamer Bits: Used for general-purpose work and minor hole enlargement. Ideal for preparing dowel pin holes.
• Tapered Reamers: Designed to create tapered holes for self-locking tapered pins or components that rely on friction-fit.
• Combination Reamers: These include multiple cutting profiles to ream different diameters or depths in a single pass.
• Adjustable Reamers: Feature movable blades that can be fine-tuned to cover a small range of diameters. Best suited for maintenance and light-duty applications.
• Cylindrical Reamers and hand reamer bits are also commonly used in manual finishing tasks where precision is essential.

Material and Flute Design Options

Bit reamers are commonly made from high-performance materials such as:

• Carbide: Offers excellent wear resistance and is suitable for hard or abrasive materials, including composites and titanium.
• High-Speed Steel (HSS) and high-carbon steel: Cost-effective and suitable for general engineering and softer metals.

Flute design also plays a key role in performance:

• Straight Flutes: Ideal for through-holes and where a balanced cut is preferred.
• Helical Flutes: Useful for blind holes or materials where effective chip removal is essential.

When Should You Use a Bit Reamer?

A bit reamer is the tool of choice when:

• You need precise holes with consistent diameters
• A drilled hole requires a smoother surface finish
• Hole alignment, roundness, or straightness must meet tight tolerances
• You are working with hardened materials or composite stacks
• You are preparing a hole for press-fit or alignment-critical components

Machine reamers and pilot reaming drilling tools are especially effective in automated setups where component fit and precision are critical.

Bit Reamers from Exactaform

At Exactaform, we supply Reamer Bits and Reaming Tools tailored for modern manufacturing environments. Whether you’re working with composites, carbon fibre, titanium, or aluminium, we offer:

• Solid carbide and PCD-tipped reamers for extended tool life
• Custom reamer design for complex or multi-diameter applications
• Straight or helical flute options for better chip evacuation and finish
• Regrind and retip support to maximise tool longevity and reduce cost

Our team can also advise on cutting speeds, coolant strategies, and pilot hole preparation for optimal tool life and cutting edges performance.

Speak to Our Tooling Experts

Need help selecting or designing the right bit reamer for your part or process? Whether you’re in aerospace, motorsport, or general engineering, our team is here to help.

Contact us to discuss your requirements and get expert support from our applications team.