Originally Posted by c0rr0sive
Photos would be nice, I have a good dremel, always used reinforced cut off wheels on mine when cutting metal, those 20 packs of small discs don't last long, at all.
Alright, as requested a quick run through on cutting round edges with a dremel. I grabbed a thick piece of scrap steel I had lying around, the tutorial will work better with a thicker piece. Don't forget your safety glasses!
So once you have your cut marked off I always start by scoring the line with the dremel. Hold the drill on an angle so that the disc makes a slight crescent shape cut. Keep it on an angle and keep going around the corner, a more shallow angle will give you a large crescent cut vs a steeper angle that leaves less disc in contact with the cutting surface. The sharper your corner the less disc you're going to want touching the surface and therefore the steeper the angle you're going to want to maintain.
After a minute or two you should have something like this:
You can see that I'm working into the corner from the scrap side, by grinding into the cut it lets me keep that disc at the angle I need it to be at to maintain that crescent shape cut for the round edge. The thicker the material the more you are going to need to grind away to get that disc into the deeper sections of the cut. I hope that makes sense.
See the difference here where I'm making a straight cut? The disc is help pretty much perpendicular to the materials.
Here I am again, well into the cut, note the angle of the disc which makes a nice big crescent cut. However, to get it at that angle I had to gring a lot of that scrap side off to get the disc in there.
Eventually the cut will be done, voila! You can see on the scrap cut off where I ground in at an angle.
Next I swap the disc for a sanding drum and do the very fine last bit of sanding to make that round corner perfect.
Touch up and last burs with a file and you should be good to go:
If I flip the cut over with the tape removed you can see that the cut doesn't look so clean on this side, in fact if you look at the outside edge which is a cut I did a while ago you can see a couple of spots where the dremel skipped out of the cut and scuffed the surface. That's why you always cut on the off side.