Q: How can I make bezels that are flat, not bent? And how do I get them flat after I’ve soldered them?
A: When cutting bezel stock, make sure when you snip each end that you are matching the angles. Make the cut perpendicular—your eye can judge this very well The trick is to cut the left end so the waste is on the right, and the right end so the waste is on the left. That is, don’t turn the bezel around to cut the other side. That’s what makes the cuts match.
For flattening the bezel after soldering, try Moore’s disks, mounted in a flex-shaft. They are brass centered sanding disks that snap onto a special mandrel. Several manufacturers make them, but not all are willing to call them Moore’s disks, as they are afraid you’ll write to the E.C. Moore Company, in Dearborn MI, and order direct. If you are getting a large enough quantity, that makes sense, but just for one case (a bunch of the little boxes of 50 or so), which usually lasts me for a couple of years, it’s just as easy to order them from C.R. Hill, a Detroit area supplier who gives us good prices on them, or from almost any of the other tool houses who carry them. My preference is for the Adalox abrasive, in medium and fine grades. I get the 7/8 inch size, and you can trim this smaller if you need by running the spinning disk against the tip of a sharp point (against the paper side, not the abrasive side, of course) or a scalpel blade. This is a useful trick, since it gives you a fresh, true-running edge which is also effective for trimming up prongs on diamonds if you’ve got a steady enough hand to manage a rather fast-cutting tool without destroying your prongs. Those little Moore’s discs are one of the most-used abrasives on my bench.
Moore also makes the more conventional (but much slower to mount) pinhole style sanding disks. I get an Adalox medium, in a 2 inch size, and a coarse (I think they are about 80 grit) also in that size. You have to mount two at a time for sufficient rigidity on a screw mandrel, but if you put them back to back, then you have a disk that will cut both front and back sides. Those large-size disks are great for cleaning up castings and larger less precise jobs. The coarse one will rip a sprue off faster than you can saw or file it off. The big danger with these disks is that they are so easy to use that you can get spoiled, and forget that for some jobs a plain old emery stick is still the tool of choice.