washer for 42 Stepper motor

解决42步进电机安装时螺丝长度不匹配的情况，有三种规格，0.5mm/1mm/1.5mm，其他规格可以用这三种规格搭配组合成。
Solve the problem that the screw length does not match when the 42 stepping motor is installed. There are three specifications, 0.5mm/1mm/1.5mm. Other specifications can be combined with these three specifications.