Why can't you fix the grinder you built?
i might be able to, but my first one was built out of 2x4's, skateboard wheels, treadmill motor with treadmill controls for variable speed.
It shredded metal at a crazy rate, but the tracking was a little wonky at times. I'd get it dialed in and then it would go sideways at first not a big deal.
But eventually I decided I had enough of it and I upped the tension to see if that would help, and it sorta did and I *really* upped the tension, and I cracked my cradle I used to hold the motor.
So i can rebuild the cradle, but decided that i want to make high quality knives and this is a fundamental tool in the process. I'm better off spending my time getting better at this and making knives instead of making tools. I like to make things but it became a no-brainer. I got a welder and created a fabrication table out of an old table saw, I was gonna get some tube steel from the salvage center and make my own.
But then... I did some math and for under 1K shipped to get a tilting, variable speed grinder with a big contact wheel, little wheel and flat platen, and it runs on 110 and uses a transformer to drive a 220v motor, and it has great reviews.
If I made one myself it wouldn't be as good, and I wouldn't really save much money at all. so better served focusing on making knives...
I also chatted with a blacksmith shop that runs classes, they had one and it is used hard there and they basically where like it's fine didn't stand out negatively or positively compared to the OBM and JET belt grinders they had there, just kinda did it's job.