I burnt up my first block grinder yesterday. It's my own fault, I've been running it too long and too hard lately. It tripped the circuit breaker on the power strip. The grinder was hot to the touch also. I let it cool and tried it again, same thing. So I tore it down, replaced some wiring inside and also the power cord. No help. It's the windings I'm pretty certain. I had a spare so no great big deal but I learned they can only take abuse so far. It was a 1/2 HP flat top. It had been getting louder over the last few weeks so I think it's time was coming anyway.
Put my 1/2 hp ( cap start) block into wire wheel duty today refurbishing a vintage Delta bandsaw, and after about an hour its making quite a bit of noise. I think its bearings, but your post made me thinking it could be something worse. Luckily bearings are a quick fix on those grinders--no godawful woodruff keys or tricky bearing holders in those blocks. Even with the noise there's no vibration or shortage of power.




