Daniel I don't think it is the material the wheel is made of that maybe causing your problem. I feel like there is something out of line. Here is a link to a similar problem I had, although by the tittle you would not guess that!
https://knifedogs.com/threads/anyone-know-why-the-kmg-grinder-site-wont-open.47807/
I enjoy making my own parts. However as I have said in other posts if you do not have the tools or the ability to build your own, so to speak, that it is best to leave it alone and buy from a source that does!!
My problem was with the bottom platen wheel. I decided to remake my platen for about the third time since I initially built my first platen. This attempt was to give myself a 10" area on the flat of the platen. Shortly after I ran it the first time, I realized I was having problems!! A lot of noise that had not been there in the first two platen's! The tracking was off and I had to move the drive wheel on the shaft.
That should have been my first clue but I needed the platen and I ventured on. Then I had a project that required using the smaller wheel on my platen. I did not realize at the time that I had been putting so much stress on the wheel till I went to change a belt and realized how hot that wheel was!! Shortly there after the noise got louder and they was a vibration there that had not been there before!
I started the machine and realized my tracking was all screwed up. That should have been my second clue but once again I needed the machine and shrugged off the obvious,
"that something was wrong"!! I could not get over the fact that noise and vibration continued and I could not put a finger on what was causing it!! This was the result! Sorry for the blurry pic but as you can see the wheel got so hot it cooked the glue that held the rubber on that wheel and the rubber let go!
2-2-2018 003 by
Clifton Craft, on Flickr
So now the platen is official downed! Sometimes my mind keeps working on a problem even when outwardly I am doing other things. So I began to rework the problems of the grinder in my mind.
First it all started when I reworked the platen. When suddenly something changes enough you have to move a wheel, dramatically that is a major clue.
Second the noise started after I got the bottom wheel hot and the position I was using the platen in, caused even more stress!! I set about to pick others brains and I was about to post photo and I saw something in this photo!
2-2-2018 002 by
Clifton Craft, on Flickr
When I saw it I had to go to the platen and confirm whether it was a problem or just an illusion created by the angle of the picture!! I pulled the platen completely off of the machine and removed the bottom wheel. I put in a stud in the hole the bolt for the bottom platen and laid a square against it. What I had picked up in the picture was true. The hole for that 1/2" bolt was threaded crooked.
If you get off even a little when starting a tap the resulting thread is going to be cantered. That bit of canter or out of square wasn't enough to pick up by eye. However it was enough to change how the machine ran the sanding belt.
I should have never had to change the position of the drive wheel just to get it too track correctly. Me leaning on the bottom platen wheel made the problem even worse. The heat caused the glue to let go but, more important it put enough stress on the bearing that the heat caused one of the two bearings to fail!!
When you build a grinder, everything has to be square and true.
Now that is not to say that the bearing on yours failed totally because of an undue strain. Sometimes bearings fail from a problem from the factory!! However it is something you need to look at!! Running a machine is like driving a car. After you run it for a while you get used to the sound. When that sound changes something is happening and you better pay attention to that change in sound. It may mean something has changed on the machine itself and it could be giving that two second warning the belt is about to explode!
