OK, so there has been a great deal of discussion about whether or not to configure the motor / mill setup with a reversing function. Is it needed? Will it ever come in handy? Can you do without it?
For me, I like to stay with the KISS philosophy, but many of our fellow brewers have found the reversing option to be worthwhile. The motor runs with the same amount of power in either direction of shaft rotation, so power is not an issue. One of our fellow brewers accidentally dropped a rag into the hopper while the mill was running. He was able to back the rag out by reversing the motor. Others have been able to back the mill shaft by hand when a situation arose which called for the shaft to turn in the opposite direction from what is used to mill grain. As far as I know, all mills will only draw grain into the rollers by turning in one direction. The only reason you would run the mill in the opposite direction would be to undo a jam of some sort. So, if that is a concern, then perhaps a reversing configuration may have some merit, and be worth the extra effort and expense to install. Although there are several ways to configure the motor for reversing operation, the best way I have seen is to use a “drum” switch, which is specifically designed for a motor application. They are a little pricey, but if you want the correct part for the job, this is the way to go. Here is a link for a drum switch offered by Zoro.
Drum switches are sold by many different vendors, and are available in several styles.
In closing, let me emphasize the importance of correct wiring for the motor, switch, plug, etc. We recommend that a licensed electrician who is familiar with motor wiring be consulted before any connections are made.
Hope this helps!