It is common practise to blunt sharp corners with radii. The known techniques vary from a coarse treatment with a angle grinder to a programmed and milled radius. Both extremes insult the eyes and the thoughts of an engineer. Be it the open negligence (which one then expects to find also in the guts of the machine) or be it the generous waste of time and money. The observer will suspect a lack of common sense in both cases. I will present you a filing technique for any radius which is very fast yet still pleasing to the eye. The secret is to approximate a radius by an octagon, then "16-gon". https://s3-us-west-1.amazonaws.com/h...ich_radius.pdf
By the way:
You can use this technique also for outer (positive) radii of turned workpieces in small lathes.
Small machines don't like the wide chips of radius tools.
Good tips. Something I see people do often is use a round or 1/2-round file to file a concave curve when they should be using a flat, square or 3-square file, the wider the better for any given radius.