What is the best way to remove cast marks from cast aluminum?

[x1rider]

I am polishing an intake manifold and would really appreciate some suggestions on the quickest way to remove the cast marks. I tried a sanding drum with a dremel but it seems a bit aggressive and the drums last 5 minutes. I also tried a 1 inch 120 grit flap wheel, that went well but I went through the flap wheel in 20 minutes. Are there any other ways to do this? Thanks in advance.

[mpierich]

Originally Posted by x1rider

I am polishing an intake manifold and would really appreciate some suggestions on the quickest way to remove the cast marks. I tried a sanding drum with a dremel but it seems a bit aggressive and the drums last 5 minutes. I also tried a 1 inch 120 grit flap wheel, that went well but I went through the flap wheel in 20 minutes. Are there any other ways to do this? Thanks in advance.

Cartridge rolls on a die grinder, felt bobs and small wheels with greaseless compound, sandpaper and elbow grease...no matter what you use it's going to be consumed in the process. Most economical (but slowest) is probably the greaseless compound since it's renewable. The Dremel won't have the guts to do much, only for tiny detailing in my opinion.

I used to start with 80 grit, but 120 is plenty. If I use 120 cartridge rolls I then also usually go over it with 120 greaseless to get rid of the ripples.

Do an archive search, there's plenty of stuff in here...

[x1rider]

Thanks a lot for your response, I will follow your instructions.

[alininger2001]

I have a few questions. Can I remove casting marks with a palm sander and sandpaper? Would felt bobs and small wheels with greasless work well with a 3000 rpm drill?

[Tng21]

ive been buying all sorts of tools lately to find the best things to use. Im currently doing an inlet manifold too. Ive blasted the inlet with a 120 grit aliminium oxide grit first to clean it down. I then bought a sanding kit like this



ive sanded it down to the best i can with the pads but they cant get in everywhere but have taken out the roughest surfaces.

Then ive gone into greaseless on felt bobs with a dremel. Like said above its the longest process, you load it onto the felt bobs, then have to let it dry hard ( quicker with hairdryer ) then sand away, when the greaseless has worn off the felt bob ( which it will do fairly quickly ) then just reload your felt bob and carry on. Ive bought a range of felt bob sizes and can get into most places on my inlet now so its just a case of getting on with it.
here's what the greaseless looks like



Hope this helps

[Tng21]

this is the inlet manifold im trying to polish, so you can see how hard its going to be lol.

dont know how id do it without greaseless now.

[jrow]

For removing casting marks on aluminum try using a diamond impregnated fingernail file. It's easy to control and it cuts pretty fast. After you use that take some 150 - 220 grit paper and finish it up. You can also use a 6" metal file, make sure that you keep the teeth clean as they will clog pretty easy. Die grinders and cartridge rolls are great, but they will gouge the aluminum if you are not real careful.

John