And that is because every different metal requires a different speed of drilling. Of course, the smaller holes could be drilled at higher speed. Stainless Steel is not hard at all, but it is very tuff. Therefore you need good quality sharp bits and slower speed drilling. Your Dremel was too fast for the job and your dad's slower drill from the 80s was just right. In this situation too slow drilling is better then too fast.
I enlarged the juice channels in my ToBeCo 28.5 mm Kayfun Lite Plus as well. Because I was getting not enough wicking issue. I took three shots at it. And my final try was successful. Only I used a different way of doing it: I made a steel nut 4mm tall, threaded to M12-0.75. The same threads of the chimney. Screw that nut onto where the chimney goes flush with the deck. And drilled right into the vertical channels with 2 mm drill bit. That way the drill bit will cut one half of the metal of the nut and the other half of the juice channel. The channel comes out perfectly strait (cylindrically shaped) and exactly the same size on both ends. See for yourself:
Edit: Ah yes, use a little lubricant/coolant when drilling SS. Your own saliva works well.
