Hi guys;
I'm looking for some ideas from any of you with experience in metal polishing. I often make up aluminum parts which need to buffed out to a level of perfection that will look good under show chrome plating. A typical part, like a couple I made up this afternoon, is made from
0.090 6061 plate, about 3" x 4" with a milled opening and a dozen various sized holes.The problem is, what's an efficient way to get the scratches out of the flat surface and bring it up to a mirror shine? The last part is easy. Once the surface is up to about 1500 grit level, it's no problem to buff it out with a sewn cotton wheel and tripoli compound. How do you get from scratches to 1500 grit while keeping the surface flat and even, without excessively distorting the holes and openings?
Right now, I'm hand rubbing the surface with a hard rubber block and various grits of emory paper. I start with 320 and go through 500, 800, and 1500, using drops of WD-40 as a lubricant. This works pretty well, but it's very tiring and takes way too much time. I need a power method of doing this.
I've tried many types power wheels, such as hard felt buffing wheels, Norton "finishing" wheels, Scotchbrite flap wheels, etc., and haven't found anything that works for this. It seems that any wheel that's firm enough to cut will tend to leave waves and ripples. Softer wheels with coarser compound would distort all the edges of the openings and holes. I've tried using emory paper on an electric "detail" sander (with the recipricating triangular pad), but that just loaded up the paper instantly and added more scratches.
Any ideas? I'm thinking of a miniature version of a random -orbit sander, with a 1" dia rubber pad, turning about 60 rpm, using various grits of lapping paste. Maybe I could rig up a small random orbit head on a drill press?
Thanks! Bruce Johnson Johnson's Extremely Strange Musical Instrument Co. Burbank, CA