划线等分中心规(图1)由中心尺1、对线尺4、滑动尺5、副尺6和滑动尺压板8所组成。因一般圆零件如盖、法兰盘等空心件的螺孔常呈3～6等分,所以,在滑动尺5上刻有3～6等分的刻线,这样,就能把零件分成2、3、4、5、6、8六种等分。如划三等分,先将对线尺4的短边对准滑动尺5上的刻线 Marked equally divided center rule (Figure 1) from the central ruler 1, on the ruler 4, the sliding ruler 5, the ruler 6 and sliding ruler plate 8 composed. Due to the general round parts such as lids, flanges and other hollow pieces of the screw often 3 to 6 equally divided, so sliding scale 5 engraved with 3 to 6 bisecting the line, so that you can put the parts into 2 , 3,4,5,6,8 six kinds of points. If you draw a trisection, first align the short edge of the reticle 4 with the reticle on the slide rule 5