It's funny to see that you are willing to spend so much time trying to sand and scrape this, when the right fix, that has been suggested multiple times, is to cut the grooves just a little deeper.
I could have knocked the new cuts out in about 15 minutes, done, no more searching for an "easy" fix...
Other than that, I would likely mask the slots, then lightly media blast them, would take the burning right out. But the time to mask and blast, and then the finish sanding after would be way beyond just cutting the grooves a little deeper.
You shouldn't need stops, just guides. When you are taking a small bite like this it's very easy to just touch the ends of the cut. Slow and steady, and just a lite touch.
Make sure your collett is tight, the bits don't creep if they are properly tightened.
Last edited by shoot summ; 09-29-2015 at 06:12 PM.