I received a PM with some questions.
I was wondering if you had a video or any progress pictures on how you are able to get those cuts. Do you use a jig with your dremel?
No, I never had a jig. Which would be quite nice for that kind of work though. What I've been doing - and actually, this is consuming more time than the cutting itself - is marking the diameter prior to cutting. I've been doing this pretty old-fashioned - using a ruler, measuring from the center point (which because of the center hole doesn't really exist so you need a good eye and the shape might not come out perfectly round anyway) and marking the to-be-cut outlines. Any irregularities from less-than-perfect cutting would have to be optimized during the sanding stage.
Usually a dremel would be a small tool as compared to a disc cutter that I've been using. I did use a dremel but only for cutting/sanding the holes on o-zone style cymbals, I didn't use a dremel for cutting the bells.
My 'technique' is being in a kneeled (and somewhat awkward) position and do the cutting while stabilizing the cymbal with my left foot. Thus, the area that I'm cutting would be hovering a few cm's above the ground which is enough for operating the disk cutter. I would cut for about 15-20 cm or so (depending on the cymbal size), then release the pressure with my right foot, rotate the cymbal accordingly to the next to-be-cut area/sector, then repeat the work. Usually it would take just a few 'rotations' to cut a cymbal. That is, if it's a thin cymbal. On thicker cymbals I would first cut an 'orientation' groove, not going through the full cymbal thickness but making sure that I'm following the marked outlines as close as I could, then repeat that process/rotate the cymbal and continue cutting that initial groove for a full rotation. I would then repeat the process but cut a deeper groove. On the thicker cymbals, a 2nd and possibly a final 3rd round of processing would be necessary.
Really, once you've done it a few times, it will be rather easy, automatized, fun to do and pretty quick. A jig would be a great thing for bigger cymbals, saving more material but also getting a steady diameter and thus, the perfect rounded shape. Actually, I might make something like that, at least for making the marking process much easier and more precise.
Progress pics or even a video is a great idea! No, I haven't any except for the pics that I've been sharing in this thread. It's a bit complicated to do this on your own, I think I'll ask a friend to help me and document the individual steps. I like to do those things in one go and also spare my neighbours the noise - or at least minimize it - because the cutting is done outside (you don't have to of course), having a better lighting situation.
Actually I bought 40 Stagg cymbal felts for my bells at the weekend - not enough for all the bells I have when using 2 of them per bell but enough to have some fun with them. I did make some cymbal felts on my own by cutting some material that I found but that stuff is only a few mm's thick - it doesn't really work as intended. I could stack several of those thin ones but it just doesn't look and feel like some proper felts so ultimately, I decided to buy some.
Still have those half a dozen DIY splashes that tend to sound too harsh/aggressive for my taste, I should sell those.