PHP 7.4.21, Port 443
Session Debug is OFF
Session ID 6oC6Z
Azure Web App Test Site

Symbols Used on Our Drawings

These symbols are used on the Mechanical Models engine drawings as well as on many other drawings.

Identifies a surface
Means that the indicated surface should be parallel to surface A within 0.10 mm
Means the bore should be perpendicular to surface A within 0.05 mm
Means that the diameter should be concentric to diameter A within 0.03 mm
Specifies the diameter, in mm
Specifies a thread. M3 means a 3 mm standard thread. 7H means a standard class of fit (that is, make it fit). The pitch for standard metric threads are as follows:
Diameter   Pitch
3 mm   0.5 mm
4 mm   0.7 mm
5 mm   0.8 mm
6 mm   1.0 mm
8 mm   1.25 mm
Indicates a surface finish of 1.6 micrometers, the same as 63 micro inches. That's a good turned surface.
Indicates surface finish of 1.6 micrometers. The circle indicates that you should not remove any material, simply use the size and finish that is provided.