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The MICROTEST® Spindel-Measurement System

How the MICROTEST® Measuring-System works 

The highly precise MICROTEST® Measuring System reaches high accuracy throughout
three measuring spindles which are operating simultaneously together to obtain the stop point at which the measurement is taken. Due to the strong vibration, generated by the ratchet, transmitted via spindles to the measurement probes, occurs the greatest possible accuracy for repeating measurement, independently of the user's sense of touch.

The plastic coating protects against spray water, dirt and thermal influence from the users hand.
The temperature-compensated design enables highly accurate measurements even ifthe standard ambient temperature of 20°C is not
achieved, since the material expansions of the work piece and the measuring instrument are
almost completely balanced out.
The MICROTEST® system is Maintenance-free!


The central shaft (6) is synchronized with the measurement probes (1) via bevel gears (4).
These bevel gears transwith the rotation from the ratchet (10) and scale drum (9), to the measuring spindles (3), which extend the extremely well-supported probes (1) to obtain a measurement.

The greatest possible distance between the outer guide and the pivot in the center remains unchanged for every measurement orientation.

The poly-carbon insulation tube (5) offers protection against spray water, dirt, and warmth from the hand. Tungsten carbide pins (2) provide low-wear contacts at the points of measurement.

The direct full read-out of the measuring results on the parallax-free scales (8,9) is faultless due to 100 divisions per turn which avoids read-out errors.

The new connection (7) offers the possibility to extend the instrument up to 10 meters, or more, for deep bore holes without loss of accuracy.

The MICROTEST® - System pays for itself

A single MICROTEST® Internal Micrometer can reduce costs by up to 50% in a short time.

Savings compared to conventional cone systems


Depending upon the size of the instrument, one MICROTEST® can replace between 2 and 6 conventional devices.

Furthermore, only a small number of calibration rings are required. Regular calibration and certification costs can be reduced to a fraction.


Estimated cost savings compared to cone system

The Advantages of our Spindel-Measurement System

Accuracy and measurement range

The MICROTEST® Spindle Measuring System is the first which succeeded in combining a high accuracy of measurement with a multiple
measuring range.
These two qualities were incompatible so far.

MICROTEST® Spindel measuring system 

Cone - System

The three-point internal micrometers currently used are based on a cone or similar-shaped system.
Those systems are very limited in measuring range
and / or accuracy.
A measuring spindle which is positioned at the top
of the instrument brings a longitudinal movement via the shaft to the cone which pushes out the
measuring probes.
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Automatic compensation of mechanical wear

With the MICROTEST® System you have an automatic linear compensation during routine adjustment.


In the measuring parent thread is a large areal layer on the thread flanks available.
This is ~ 1,000 times larger than the line at the
cone system. It can have only minimal wear, which affects the entire linear range. This wear is
hardly detectable.

MICROTEST® Spindel measuring system 

Cone system: The measuring probes touch the
cone by a line that wears quickly, which only applies locally and non-linear. This problem is often not taken into account in the calibration
procedure, since calibration rings are usually only present at the end of the measuring range.
This can lead to significant inaccuracies.

Compensation is impossible!

Cone - System

Reduced thermal influence

The MICROTEST® system demonstrates proportional, linear behavior with temperature expansion errors largely compensated. Results at non-standard temperatures (not 20°C) approximate the accuracy of measurements in the room. Despite being largely temperature-independent in design, our measurement unit is insulated at user contact points to prevent unwanted heat transfer from the hands.

Conventional cone systems exhibit undefined and uncontrolled behavior, dependent on the expansion of connecting elements between the cone and measurement spindle during the measurement. Typically, there is no protection against heat transfer from the user's hands.

MICROTEST® Spindel measuring system 

Cone system

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Our 3-dimensional centric system

The MICROTEST® System provides a person-independent repetition accuracy of  ± 1µm.

MICROTEST® System: The extended contact line of the probes ensures optimal three-dimensional centering, while the scale head's hard ratchet induces vibrations transmitted to the probe/spindle system, facilitating fast and accurate centering. The consistent measuring pressure eliminates the need for manual "sense," ensuring a repetition accuracy of ±1um, irrespective of the operator. (up to 400)

MICROTEST® Spindel measuring system 

Cone System: While the clutch coupling allows for constant measuring pressure, it lacks support for centering and induces tilting in the hole, resulting in a scatter of approximately ± 3-5 µm. The ratchet offers improved centering but presents issues as repeated ratcheting causes the cone to penetrate too deeply into the probe system, leading to distortion and increased scatter.

Konus System

Comparison 2-Point measuring device

Swiveling internal measuring instruments determine the turning point by commuting around the solid plunger. The minimum value is identified through a dial gauge, indicated by the pointer changing direction. Typically, a limited measuring range is accessible, and proper handling involves manual coordination of two axes, relying on a tactile sense.

Handling pole systems is challenging, requiring manual movement of the built-in measuring spindle while simultaneously stabilizing two axes manually. The centering process demands knowledge, patience, and a keen sense of touch. The high time consumption results in significant heat transfer from the hand to the device, leading to potential measurement errors.

Swivel system

Rod system

Comparison of shape error detection

In the machining of bores, very often 3-jaw chuck or collet chucks are used. This has the consequence that the workpieces can be deformed.


These polygon deformations can significantly affect the quality, or even create scrap.
An accurate measurement is only possible with 3-point tools, in which the probes are arranged at 120 °

By changing the measurement position, the difference can be determined from the largest to the smallest diameter.

MICROTEST® Spindel measuring system 

In egg-shapes or undefined forms, the 3-point instrument is also an advantage, because the centering is performed automatically. Pure ellipses are very rare.

A 2-point unit can only record the average of the diameter.  The 180 ° arrangement of the probes, always detects the highest and the lowest point of the shape, at the same time.


Accordingly, the hole appears to be around, even though a considerable polygon error.


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