Outside Micrometers.

What are Outside Micrometers?

Outside micrometers, often referred to as external micrometers, are one of the most fundamental and widely used precision metrology instruments in engineering. They are specifically designed to measure the external dimensions of an object with incredible accuracy.

Unlike their internal counterparts, an outside micrometer is used to gauge features such as the diameter of a shaft, the thickness of a plate or the length of a component. The classic design features a solid C-shaped frame which holds a stationary anvil and a movable, calibrated spindle.

How Outside Micrometers Work

An outside diameter micrometer operates on the principle of a precision-ground screw. The object to be measured is placed between the flat faces of the anvil and the spindle. By turning the thimble, the user advances the spindle along a highly accurate thread until it makes light contact with the object, gently securing it against the anvil. The final measurement is then taken from the graduated scale on the sleeve and thimble for an analogue model, or read directly from the display of a digital micrometer.

As a real-world example, imagine a CNC machinist producing a critical driveshaft for a high-performance gearbox. The outer diameter must conform to exacting tolerances to ensure a perfect fit within its bearing. The machinist would use an outside micrometer to verify this dimension down to the micron level, guaranteeing the component meets the rigorous quality standards required for reliable performance under load.

Materials Outside Micrometers Are Made From

To ensure consistent accuracy and a long service life in a professional workshop environment, Accu's range of outside micrometers are manufactured from high-quality, durable materials.

• Stainless Steel: The core components, including the frame and spindle, are crafted from premium stainless steel. This provides exceptional rigidity to prevent frame flex during measurement, along with excellent resistance to wear and corrosion, safeguarding the tool's precision over years of use.

Sizes and Types of Outside Micrometers Available

Our comprehensive range is designed to cater for every engineering challenge, from small-scale prototyping to large component manufacturing. We supply outside metric micrometers capable of measuring ranges from 0mm up to 1000mm, delivering world-class precision with accuracy down to an exceptional 0.001mm.

You can select from traditional analogue micrometers, which offer proven mechanical reliability, or advanced digital models that provide error-free readings and can feature wireless data transfer to streamline your quality assurance processes. For enhanced durability in high-volume applications, many models are available with carbide-tipped measuring faces. Additionally, a UKAS calibration certificate can be supplied to ensure full traceability.

FAQs

Q: What is the difference between inside and outside micrometers?

A: The fundamental difference is their application. An outside micrometer measures the external dimensions of an object, like the diameter of a rod. An inside micrometer measures internal dimensions, such as the diameter of a hole or bore. They are two distinct metrology tools designed for opposite measuring tasks.

Q: Can outside micrometers measure internal dimensions?

A: No, an outside micrometer cannot measure internal dimensions. Its C-frame and anvil/spindle design are constructed exclusively for accessing and measuring external surfaces. You would need a dedicated tool, such as an inside micrometer or a bore gauge, for internal measurements.

Q: What is the ratchet stop on a micrometer for?

A: The ratchet stop or friction thimble is a crucial feature that ensures measurement consistency. It is designed to slip at a preset torque, applying the same, optimal amount of pressure for every measurement. This prevents the user from over-tightening the spindle, which could lead to inaccurate readings or damage the component being measured.

Q: How do you care for an outside micrometer?

A: To maintain precision, always wipe the measuring faces of the anvil and spindle clean before and after use. Store the micrometer in its protective case with the measuring faces slightly apart. Avoid dropping the instrument, and periodically check its zero setting by closing the faces (or using a standard for larger models) to ensure it reads correctly.

Bespoke Outside Micrometers Manufacture.

High precision, bespoke manufacture of Outside Micrometers to customer specification. State of the art facilities specialising in both small batch prototyping and large scale manufacture.