While drilling the two outside, 1/2" recesses for the SOSS hinges I realized that I needed to clean-up the inner edge of the recess. The solution I came up with was right at hand - the hollow, metal end of an "acid brush" (disposable glue brush). The thin, rolled metal tube that makes the handle of the brush had just enough of a cutting edge to clean out some of the remaining shavings that just wouldn't break free.