The jitter is too outrageous. What happened?

Ask the landlord to balance the grinding wheel first. See if it works. If you really can't balance, you can find a grinding wheel supplier to deal with it. You can't say that the grinding wheels in Guangdong are poor. As far as I know, the grinding wheel used in Ningbo, Zhejiang Province is very cheap. I am now working as a centerless grinder in Ningbo, which is worse than that in Guangdong. But it does not rule out that some grinding wheels have quality problems, so don't kill them with one pole. First, calm down.