JD9A/JD21/JD10A type projection measuring instrument with a length of 2.3 metersDetailed product description：

JD9A/JD21/JD10A Projection Two meter and Three meter Length Measuring Machines

1、 Characteristics:
The base is made of high-quality cast iron and has undergone long-term natural aging treatment to ensure sufficient rigidity and stability. Real time correction of Abbe error using the principle of Einstein optics. The projection reading screen adopts a novel projection system with clear image surface. The measurement accessories are complete and have a wide range of applications.

2、 Purpose:
Projection one meter, two meter, and three meter length measuring machines are large precision measuring instruments for length measurement. It can accurately measure the internal and external dimensions of some ultra long workpieces, and use comparative methods to calibrate fourth and fifth order measuring blocks with dimensions greater than 100mm, as well as calibration measuring rods for direct measurement of outer micrometers, inner micrometers, and self-made measuring rods. Measure the internal dimensions, inner diameter, and external thread pitch diameter of various card boards. This product is widely used in various mechanical manufacturing industries, including aerospace and railway locomotive manufacturing, research institutes, metrology and calibration institutes, and other departments.

3、 Specification parameters:
1. Measurement range (mm) External dimensions 0-1000, 0-2000, 0-3000 Internal dimensions (depth from 5-50 when using size measuring hooks) 13.5-900, 13.5-1900, 13.5-2900 External thread diameter measurement up to M140mm
2. Minimum division value: 0.001mm
3. Accuracy of measuring external dimensions:
(1) The indication error of micrometer ruler: ≤ 0.20 μ m within ± 60 μ m range, ≤ 0.25 μ m beyond ± 60 μ m range
(2) The indication error of millimeter ruler is ≤± (0.6+L/200) μ m
(3) The indication error of the micrometer ruler is ≤± (0.5+L/200) μ m, where L is the measured value in millimeters
4. Measurement of indication variability when the axis moves multiple times: External dimension measurement: ≤ 0.1 μ m Internal dimension measurement: ≤ 0.5 μ m
5. Measurement force (N): 0.4 External dimension measurement: 2 ± 0.2 Internal dimension measurement: 1.5~2
6. Universal worktable (mm): Vertical stroke: 0-70 Horizontal stroke: 0-40 Horizontal position Vertical floating stroke: 10 Horizontal micrometer drum indexing value: 0.01 Workbench load: 10kg
7. Maximum clamping diameter of top needle holder (mm)
(1) When the length is between 0 and 170, φ140
(2) When the length is between 170-210,: φ 130
8. V-shaped bracket
(1) Height adjustment range (mm):>28
(2) Supporting workpiece diameter range: up to diameter 30
9. Gauge block bracket: supports gauge block length up to 1000mm
10. Measuring rod bracket: supports measuring block length up to 1000mm
11. Measuring block grinding frame: The grinding length of the measuring block frame is up to 100mm
12. Working range of V-shaped iron: up to φ 45mm
13. Instrument dimensions (mm)
JD9A 1980×450×750
JD21 2980×450×800
JD10A 4000×450×850