I know that I am a bit late chirping in but I just saw the link on Pinterest.

One thing that is often forgotten or not realised is that the vast majority of the "grit" when grinding steel or iron is steel or iron not grit from the wheel. So I mount an enclosed magnet right in the spark path and it captures the vast majority of the "grit". If you watch the sparks you can see the tracks bend towards the magnet. Of course this does not apply when truing the stone when all of the grit is grit.

I tried this type of grinding on my mill. I had a 5" cupped wheel that I use on my T&C grinder but that was a bad mistake. It was a CBN wheel which have a thin layer of CBN on an aluminium cup. What does aluminium do well when it warms? It expands. So as it warmed whilst grinding the depth of cut increased, raising the temperature even more rapidly and quickly becoming a runaway condition. It quickly locked the spindle and that has a 5 hp motor.

Now I use an Al-Ox cupped wheel and the problem is non-existent. Flood cooling the CBN wheel may have been a practical way to solve the problem also.