如果采用如附图所示的划尺划中心线,是非常方便的。中心线划尺的制造很简单:在直角尺1上,加上一个尺苗2,使尺苗2的一边和直角尺的一个里边成45°角,然后用梢钉或焊接方法固定。使用时,把直角尺的里边靠在或棒料的外径上,用划针沿尺苗2来划,然后移动中心线划尺:再划一垂线(近似垂直即可),两线的交点便 It is very convenient to draw the center line by using the plan as shown in the drawing. The centerline ruler is easy to make: at the square 1, add a ruler 2 so that one side of the ruler 2 forms an angle of 45 ° to the inside of the square and then fix it with a spiked or welded method. Use, the rectangular inside of the ruler or bar on the outer diameter, with ruler along the ruler 2 to draw, and then move the centerline ruler: then draw a vertical line (approximately vertical), the intersection of two lines Will