Topic: Polishing aluminum

[d9canada]

I've done metal polishing since the 60's, back then for pocket money doing motorcycle stuff, over the years for my own bikes and boat stuff.  By far the best articles I've ever read for this and some related issues at  http://www.caswellplating.com/buffs/buffman.htm

Yesteday I stripped all the engine cases, rotor and clutch off the blown motor in my parts bike, preparing for a new motor to make the beast live again.

I've been using Home Depot's Behr paint stripper spray for a number of years.  Do this outside!  I sprayed all the aluminum parts, left them to sit 20 min, then scrubbed real well, wearing Nitrile gloves & eye protection, using green Scotchbrite pad, then rinsed thoroughly with water.

My polishing rig is very basic, just a simple arbor stand for grinding, with an 8" sewn cloth wheel (about $10) and 1HP motor.  Using a bit of fast cutting emery (black) and medium cutting tripoli (brown) compound, I had the covers off that motor looking great in just a few hours.  You can buy a pack of assorted compounds for about $12 that will last you a long time. 

You can also use various cloth wheels on small grinders, Dremel tools, die grinders, etc. The little guys are great for nooks and crannies.  I use the same sewn cloth wheel for black and brown compounds. I have a loose cloth wheel that I use exclusively with fine polishing red compound. 

The clutch cover was so nasty I had figured I'd be best to hit it with at least 600 grit wet/dry first, but nope, it shined up nice. What a great way to finish up a bunch of grunt work instead of having a box of grungey old parts, I have a bench of gleeming stuff!

Winter's coming, so you might want to give it a try.  DO wear eye protection, a simple dust mask, coveralls are good - this process is a bit messy.

[d9canada]

Here's an update that I hope will save you some money and maybe open up polishing to people with Dremels.

I am always on the hunt  for cheaper better methods and materials.  I generally use my bench polishing rig for as much as possible and occasionally also use a die grinder with a 3" buff wheel or cone.  Recently I wanted to use my Dremel clone with flex shaft.  But there's a problem  , and a solution

A standard Dremel mandrel is a glorified screw that holds one buff that costs about $4.  Try a drywall screw instead, with the head cut off.  It's shank diameter needs to be just slightly ground to make it fit in the Dremel chuck.  I bought a huge pack of chair glides from Homie Depot that cost $10 on special.  In Dremel terms that works out to about $200 or more. 

Carefully remove the sticky backing on a glide felt.  Once you get a corner pulled up, grab it with pliers and you should be able to rip the sticky part right off.  Then, with the drywall screw in the chuck, carefully wind the felt on by hand.  Note that unlike the Dremel set-up, you can stack several felts.  These work well with standard color coded polish compounds.

The problem with all of these rigs is the center of the felt tends to tear out.  I am currently experimenting with glues to avoid this issue.  But at least this option will reduce your cost. 

You can also use circles cut from old sweat pants or jeans for buffing liquid polishes.

[dixiedevil]

I have used this with very good result (with die grinder). If i can find a picture i will..

http://www.homedepot.com/h_d1/N-5yc1v/R-202886254/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=buffing+and+polishing&storeId=10051

$10.00

[mono]

recently polished up a lot of aluminum parts on my 550 (forks, engine cases, etc).

I did not want a mirror finish, but close to mirror, and got great results in 4 steps:

1. wet sand with good quality 600-grit paper to remove the factory clearcoat and sand out any dark oxidation spots.  i say "good quality" because i bought a pack of wet/dry paper from harbor freight and it left a gray residue, making the aluminum look dirty.  also, the grit quality was pretty uneven.  i ended up using some 3M sandpaper and it worked so much better.  ya get what you pay for i guess!
2. (this is actually counter-intuitive) - i used a 4" 400-grit 3M radial bristle wheel (blue) that i have mounted to my polishing motor to give everything a satin finish.  the 3M radial bristle wheels are actually very non-aggressive, and the 400-grit left a nice smooth satin finish - comparable to 800-grit.
3. buff with a 6" stitched cotton wheel and tripoli.
4. final hand-polish with Blue Magic and a microfiber cloth.

I'll be posting images of this process if i can ever locate my build thread.