Among the tools Sonex recommended when I started building my Sonex was a stand-mounted motor fitted with a Scotch-Brite wheel. Its purpose was for deburring the edges of the many parts that make up an all-aluminum airplane. I bought both and quickly regretted it. I sold both and replaced them with simple, low-cost flapper wheels, and I’ll tell you why in a moment.
The motor buffer was heavy to move and required floor space; not only the floor space it physically occupied, but floor space in front and behind, so parts could be introduced to the wheel without interference. Feeding the cut edge of long extrusions was difficult. Cleaning up the edge of thin sheet metal required care so the wheel wouldn’t get grooved or cupped. The wheel’s aggressive cut meant caution was needed on thin parts, to keep from removing too much material. Lastly, the Scotch-Brite wheel’s narrow width and proximity to the bulky motor prohibited its use for cleaning up wide surfaces.
My solution was to switch to Scotch-Brite flapper wheels chucked in an electric drill—that is, until they went from $5 each to north of $65 each. Sorry, my budget for abrasive finishing tools isn’t that big. I found Ace Hardware stores carry a suitable substitute, for $11, and stocked up.
Flapper wheels chucked in a drill will go anywhere I need them to. They are long lasting and can clean up thin edges as well as wide surfaces. They also ease the corner of parts a bit, whereas Scotch-Brite wheels left a crisp (sharp) edge, which is not to my liking. Although I took advantage of access to a Scotch-Brite wheel while working at Sonex, my preference for my shop, and even for the final finish on parts cleaned up with a Scotch-Brite wheel, is the flapper wheel.
I seem to recall the FAA recommending 400 grit aluminum oxide when finishing aluminum. That’s what I’ve been using, although that flapper would speed up removing the worst of the roughness.
Might save even more money by using Dremel flapper wheels (on a Dremel tool vs drill) — come in multiple grades and work GREAT!!!
Scotch-Brite wheel mounted on a bench grinder is my primary tool for deburring aluminum sheets & smaller parts, if done carefully even large wing skin sizes can be done this way. Always present the sheet edge at an angle to the Scotch-Brite wheel to avoid cutting a groove in the wheel preserving the wheel & not creating snags. Two cautions, always approach corners at angles that will not catch the wheel, saves both the wheel & part from damage. Second caution, securely clamp any piece you are deburring if you use a drill mounted wheel preventing a potentially very nasty cut if the wheel snags in any way.
I use a generic scotch brite wheel that is reasonably priced for extruded parts:
https://a.co/d/0fgyG91i
And 600 grit wet/dry sanding pads for edges and left over burrs that my deburring tool doesn’t get on up-drilled rivet holes:
https://a.co/d/01HZ90a9