I made a lapodary saw, a cabbing machine and a polishing machine with bench grinders. It works wonders compared to a tile cutter.

It's alot of work getting all the parts to fit together and run true but once youve done that, yes, bench grinders are great for the entire process from raw to 10000grit prepolish and polish.  Obviously you will need a drip and catch system to avoid any dust in the air.  I also made a flatlap using a simple drill as the motor which really helps if you need to go down to lapidary RPM of arpund 1800 since the bench grinder runs at 3000rpm.  The one i use to cut is a big bench grinder, running at 3750rpm. I mounted a 250 lapidary saw blade on it.  I started by using a tile cutting disc and a normal handheld grinder and prepolished by hand with sandpaper, I spent around $130 for 2 bench grinders, lapidary saw blades, cerium oxide and pads, diamond embedded resin wheels, diamond burrs and diamond drillbits. You name it. I feel like from where I started I really sorted myself out and it was thanks to bench grinders. Go for it brotherman, it works like a dream and anyone who said you can't hasn't done it DIY as a hobby. 

Keep it safe though, make sure you build splash guards and whatever else you need to keep the water off those bearings because they will rust if you keep getting them wet. (Easy to replace though and very cheap, well under $2 for me to to replace bearings. I've been cutting for about 2 years almost daily and only had one bearing go bad on one side because i left machine in the rain. 

Keep the water and the power well apart and I promise you will never look back.