Looking for some advice on polishing cast rough brass.Thanks Jim
What are you hoping to polish? I'm thinking you mean rough as in sand cast? Is this something that should be polished? Some items can be more difficult than others.
Rough cast as in sand-cast ? Files to refine the surfaces to a plane, then wet-or-dry sandpapers of increasingly finer grits. After "floating" with a fine cut file, 360 grit is good, followed by 600 and micro-fine "color sanding" papers, 1800 to 2400. After that, a good polish will bring up a high lustre. Use a block when sanding flat surfaces. If you have access to buffing wheels, a semi-loose cotton wheel and jeweler's rouge will bring up a high lustre.
James I did a Moto-meter makeover using some rough cast brass plumbing caps. I did everything by hand, no polishing wheel or rouge, which of course would work perfectly. The filler neck was chrome, I stripped and then polished it at the same time. I sanded everything smooth with #400 grit 3M wet or dry paper(dry), followed by the same type paper #500 grit. Then I hand polished with old t-shirt rags with Blue Magic polish several times until it suited me.
James I use a file, then worn out belt on my belt sander. Hard to reach spots sand by hand with 320 / 400 / 600. Then use the 6" bench buffer wheel, and hand held air motors with 4" buffer wheels. The buffer wheel work is all done with jeweler's rouge, red then green.
Once the buffer has done all its work finish polish with a rag and Mother's metal polish.
Royce, I thought red rouge was the finest of all buffing compounds. I have three blocks I use. First the white for steel and bad scratches, then the green and lastly, the red jeweler's rouge. The buffing compound blocks McMaster-Carr sells says that white is 2 microns, green is 1 micron and that red rouge is for brass and copper and is 0.5 micron. Go to www.mcmaster.com and type "buffing compounds" in the search box, then click onto smoothing and buffing compounds. Jim Patrick
Depending on size I use a random orbit up to 400 then can transfer to a wheel. A lot depends on the quality of the casting.
These started out as a propeller shaft that had been sunk for 50? years
Yep, backwards. Green first.
A stainless steel .006 wire wheel will put a good shine on the cast parts that are difficult to reach or that you don't want to grind smooth.
On this car I'm building Ill forgo the polish look and tumble most pieces then steel wool and let tarnish cleaning with steel wool then let go.
Thanks to all, great advice. Jim