The quality of the rotary screed mainly depends on two points, the first is the design of the thread, divided into full thread or half thread, full thread lasts longer and is not easy to slip, and it is easier to rotate: the second is to look at the steel needle, the steel needle should first be chamfered round enough so that it will not hurt the enamel of the tile when rotating, and the hardness of the heat treatment should be just right, not too hard or too soft. Too hard easy to break too soft easy to deform. The last point is that the steel needle of the screed can not be directly used to leave the seam because it needs to rotate back and forth, to be used with the cross card, first use the cross card to leave a good seam, and then use the steel needle into the seam to rotate the screed, the thickness of the steel needle of the factory is 1.5 mm round needle, so the seam of 1.5 mm and above can be easily flattened.