JB/T 12640-2016Vernier marking compasses (English PDF)

National Standard of the People's Republic of China

ICS

17.040.30

Issued by: Ministry of Industry and Information Technology of the People's Republic of China

Contents

• 1 Scope
• 2 Normative references
• 3 Terms and definitions
• 4 Type and basic parameters
• 5 Requirements
• 5.1 Appearance
• 5.2 Interaction
• 5.3 Difference in the projecting length of the scribing (measuring) jaws
• 5.4 Material and hardness of the measuring face
• 5.5 Surface roughness of the measuring face and of the reference face
• 5.6 Scale marks
• 5.7 Distance from the edge of the surface of the vernier scale marks to the surface of the main scale marks
• 5.8 Zero/initial value error
• 5.9 Flatness and parallelism of the measuring faces and closing gap
• 5.10 Maximum permissible error
• 6 Inspection conditions
• 7 Inspection methods
• 7.1 Appearance
• 7.2 Interaction
• 7.3 Difference in the projecting length of the scribing (measuring) jaws
• 7.4 Hardness of the measuring face and of the scribing head
• 7.5 Surface roughness of the measuring face and of the reference face
• 7.6 Scale marks
• 7.7 Distance from the edge of the surface of the vernier scale marks to the surface of the main scale marks
• 7.8 Zero/initial value error
• 7.9 Flatness and parallelism of the measuring faces and closing gap
• 7.10 Indication error and scribing error
• 8 Marking and packaging
• Annex A (informative) Quantitative inspection methods of the interaction
• A.1 Inspection of the moving force and of its variation
• A.2 Inspection of the shake
• Annex B (normative) Inspection method of the flatness
• Figure 1 Type I vernier scribing compass
• Figure 2 Type II vernier scribing compass
• Figure 3 Diagram of the inspection of the type II vernier scribing compass with centre distance gauge blocks
• Figure B.1 Diagram of the inspection of the flatness of the measuring face