Precision steel rules

Use a square on one datum edge and measure the distance from the other datum edge using a precision steel rule. Scribe lines. 

Measure from each long edge and find the centre using a precision steel rule. Scribe the centre line using the edge of the rule as a guide. Find the centre of the small radius by measuring from one end the size... 

Using dividers, set the distance from the centre of the small radius to the centre of the first small hole. Scribe an arc. Repeat for the second small hole and the large radius. Centre dot at the intersection of the centre lines. The dividers are set using the graduations of a precision steel rule. 

Complete the profile by scribing a line tangential to the two radii using the edge of a precision steel rule as a guide. 

Clamp the plate to the face of an angle plate, ensuring that the clamps will not interfere with marking out. Use a scriher in a surface gauge and set the heights in conjunction with a precision steel rule. Scribe the datum line. Scribe each horizontal line the correct distance from the datum. 

Using a precision steel rule measure from two adjacent edges to determine the datum point. Centre dot the datum point. 

The national standards for the coal mine equipment shell material are clear. But the material is not ruled strictly for the mine robot flame-proof enclosure. The cast steel, ordinary mine equipment shell material, couldn t meet the requirements of the AMDR obviously with high precision and high maneuver performance. Light alloy with low density and high intensity is the best choice of the AMDR flame-proof encloser material. 

Because of the temperatiire dependence of the oxygen partial pressure of these systems, it is particularly important to know it with precision. As a rule of thumb 10 % precision in O2 determination in steel requires knowledge of the temperature within 10 C and the tension within 2 mV,... 

---