Originally Posted by
Mike Blue
The short and sweet answer is go slow and cool the blade often. Do not wear gloves that you can feel the heat build up and even then cool the blade before you think you should.
Mechanically a larger grit rides across the steel with less surface area than the finer grits. The more surface area contact on the blade the more heat generated. As you step down through the grits, the finer grits also break down easier leaving more surface area contact hence more heat, and the more important to slow down and cool often, especially after heat treatment. The VFD is a handy device. Rather than get into RPMs and belt speed, you will likely find yourself running in the 10-30% range of motor output.
Again, slow and careful. Another example is that if you finished your blade at 60 grit and then heat treated. You now have those scratches to remove and they are harder to remove than when the steel was annealed. It will take more pressure at 100-120 grit to remove them and that risks additional heat. Once you are past about 400 grit equivalent or 60 microns, things will go faster but you risk the blade being hot before you know it and can get to the water bucket.
There are water cooled wheel arrangements. They are messy but they work. The wheels turn slower than you might think would get any work done.
It's a combination of the operator's pressure on the material, grit size and surface area and sensitivity to heat build up that will help the most.