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Abstract:
This video features "#measuringhero Nobby" showcasing a vintage Zeiss Universal Measuring Microscope (UMM) dating back to the 1930s. Acquired from the University of Ghent, this historically significant instrument weighs approximately 450-500 kg and rests on its original oak table. Nobby explains its functionality as a 2D measuring machine using a microscope for viewing and separate X/Y slides with dedicated eyepieces to manually read glass scales down to micron-level precision. A key design feature highlighted is the separation of the X and Y axes guideways, minimizing stacked errors—a principle echoed in modern Zeiss O-Inspect machines. Nobby demonstrates measuring a 20mm ring gauge, illustrating the meticulous, manual process involving focusing, aligning crosshairs, and reading scales, ultimately obtaining a feasible measurement. The UMM's capability to measure complex thread parameters (diameter, pitch, angle) using accessories and a tilting head is also mentioned, contrasting its elaborate manual operation with the speed and automation of modern CMMs.
Stepping Back in Time: The 1930s Zeiss Universal Measuring Microscope
0:05 Introduction: Jay visits Nobby in the Netherlands to see a special piece of equipment.
0:28 Historic Machine: Nobby introduces a Zeiss Universal Measuring Microscope (UMM) from the 1930s, a foundational piece of measuring technology.
0:39 Acquisition Story: Nobby acquired the machine from the University of Ghent in Belgium several years after seeing it there and expressing interest.
1:43 Physical Characteristics: The main unit weighs 450-500 kg (around 1000 lbs), sits on its original heavy oak table, and uses an external power unit for its three light sources (for backlighting).
2:25 Basic Functionality: It's a 2D (X/Y) measuring machine that uses a microscope to view the part. Measurement relies on moving the X and Y slides.
3:09 High-Precision Manual Reading: Measurements are taken by manually viewing glass scales for the X and Y axes through dedicated microscopes, allowing readings to a thousandth of a millimeter (micron) and even finer divisions.
4:16 Advanced Guideway Design: The machine features precision-ground guideways with a notable design where the X and Y axes are independent, preventing the accumulation of errors common in stacked designs. This principle is revisited in modern Zeiss O-Inspect systems.
5:47 Measurement Demonstration: Nobby demonstrates measuring the diameter of a 20mm ring gauge, a multi-step process requiring careful alignment and manual readings.
5:59 Manual Measurement Process: The operator must focus, align the crosshairs on the feature edges (e.g., 12 o'clock, 6 o'clock, 9 o'clock, 3 o'clock positions), and then move to the scale eyepieces to read the precise positions.
7:49 Measurement Result: The manual two-point measurement yields a diameter of 20.003 mm for the 20mm ring gauge, showing a deviation of 3 microns, considered a feasible result given the machine's age and uncalibrated state.
8:23 Versatile Capabilities: The UMM was designed with accessories to measure complex features like screw threads, including parameters like major/minor diameter, pitch, and flank angle, facilitated by a tilting microscope head.
9:16 Historical Context & Modern Comparison: The manual process was time-consuming ("took ages"), with the operator acting as the "reader head." This contrasts sharply with modern CMMs that can perform similar measurements in seconds using automated programs.