1.      operator is not careful, when mistakes in measuring child, or dial a mistake and improper use of

Measurements carefully, the proper use of the dial is a very important extension units handle dial, the dial of the various models of lathe is not the same, each small dial can be used the following formula :

Scale switch to move the distance of a cell turning tool = extension unit, screw distance /dial a total groove number of cells (mm)

Know the scale value of each grid, but also pay attention to when using the gap between the screw and nut, and sometimes the dial rotation, but the turning tool will not necessarily move the gap transfer finished turning tools before moving. So, when used, if the scale turned his cell number too far, and will never allow the upside down only a few cells, but to reverse a turn, re-alignment scale.

2 measuring errors or use no release is

Use measuring tools should be carefully examined and adjusted, to put to use.

Due to changes in temperature, the size of the work piece changes

cutting, chip deformation, chips of various molecules with each other and move, they move the friction generated a lot of heat. In addition, because the friction of the chip and turning tools in front of the lathe tool behind the surface friction produces heat, the heat directly affects the tool and the work piece up. Of course, the highest heat chips (about 75 percent), followed by the turning tool (about 20%) and work piece (about 4%, 1% in air).When the heating of the work piece diameter (about 0.01 to 0.05 mm larger cast iron changes than steel material), diameter shrinkage after cooling, resulting in waste. It can not be measured in the high temperature of the work piece. Must side the amount of pouring plenty of cutting fluid in turning, the work piece temperature; followed by separate coarse and fine cars.