How to use expansion screws

Find a steel pipe with smooth inner diameter, which is thicker than the expansion pipe of No.8 expansion screw, grind one side of the steel pipe wall into the shape of a knife edge, then put the steel pipe on the outer side of the expansion screw with a hammer, knock it into the wall, knock it at the end with the same steel pipe until the screw of the expansion screw is exposed, then pad a large gasket on the steel pipe, and install a nut on the exposed screw and tighten it hard. Until the expansion screw is completely pulled out.

The advantage of this is that the stress position is only concentrated on the steel pipe and the expansion screw, which will not damage the wall.

But it is relatively complicated to do. If you think you can knock it in, you don't need to polish the steel pipe. However, it is better to find the steel pipe with smooth inner wall, and it will be easier to oil both inner and outer walls before construction. )