Create Belt Grinder (2'x48' )

Hello, I'm Mongzak.
It has a subtitle function, so if you need an explanation, please turn on the subtitles.~
This task is to create a belt grinder.
It's too expensive to buy a belt grinder, and I feel like my shoulders are going to hurt.
So I made it.
Roller to board wheel, motor to handgrinder,
For speed control, we used a pre-volter (voltage controller) .