Sand before Polish

[DMAT]

I got some alloy pieces that have noticable machining marks that were revealed after some deanodizing. straight polishing just takes way too much effort to get shined up so I went to a sand paper first.

At moment, it seems like a 500 grit is enough to get the metal to a polishalbe stat.

Do you guys use a higher grit when doing this? whats your preference? I've usually been able to get by with polishing but some parts are just not worth the effort.

I got a variety pack from harbor freight with the 220/500/1200/2000 sheets so I'm open to trying the other grits.

[Coelacanth]

For pretty bad scoring, I'd probably start with 400 grit, then move up from there. For just removing minor oxidation, probably start with 600. For best results, and less effort, don't jump up too much in grit...400, 600, 800, 1000 and 1500 probably. If you jump up two or three grades, you'll have that much more work to do to remove the sanding marks from the previous stage.

[Kyoshojoe]

Ive usually followed the usual process of coarse to fine grit then wheel it and wax. I asses the piece and guage the random issues. grain, scratces, oxidation, dents, etc. and each scenerio require different repair prep before just getting rid of sanding marks. in the case of machining marks I would say its gonna take either a heavy grit or jewlers file. I always end up making tools for the drill or dremel too, just be cautious and remember that sanding is scratching away material and it will cut as deep as the texture allows. I generally start with a 180 automotive dry paper and polish out the scratches with it using 400 then 600. One tool ive found to be indespensible is scotchbrite polishing balls. they are about the size of a baseball and come in three grits. heavy med fine. med gets alot of my filling marks out when I fab a piece. the fine gives a good satin polish about the sheen 400 gives. I chuck em into my drillpress. they use a standard 1/4 arbor so it will work in a cordless drill. they are great for making fast work of cleaning up small alloy parts that have intricate shapes. eg. kyosho optima steering knuckles. there like 10 bucks ea at harbor freight and last forever. i only use med and fine and with some mechanics gloves I can hold the part and work it around.

[DMAT]

forgot who said but mother's mag polish is about the equivalent of 2000 grit. I might try to jump to the 1200 i have before hitting it with the dremel polish pad.

[Kyoshojoe]

try using wool pad when using polishing compounds they hold up good to the scrubbing and will actually polish pretty good without compund too. also never dull is an awesome polish as well, it comes as a wadding and works magic on rusty crome to pitted aluminum. went through lots of cans keeping my magnesium valve covers shiny on my old t-bird. you might even be able to make a dremel bit with the wadding on it and save some elbow grease. its awesome stuff and cleans and polishes about every metal. of course it wont get scratches but oxidation and stains are usually no problem. aluminum doesnt rust because it forms a oxide coating that can lock in stains from salts and oils. different aluminum alloys react differently. kyoshos duralum is extrmely rigid and strong but suffers from tarnish and oxidation issues if not waxed or annodized. also if you wet sand add a drop of dawn in the water to help keep paper clear and it cleans dirt,wax, and oil from the metal too. thats a painting trick but works with polishing too.