streamlining sanding of cast aluminium parts

[rotorman]

Hi, haven't posted in a few years!

I've gotten fairly good at polishing now, and am confident once I have a uniformly prepped piece at 400 grit or so, I can get the desired finish.

BUT, here's my problem. Sanding takes AGES!

How do the pro's do it?

I have some cast aluminium alloy parts - intake manifolds, throttle bodies, alternator casings etc, and i want to get out the pits left from the casting process, and smooth the rough cast finish.

I do this with emery paper. Usually I use water on the part to keep the metal fillings from rescratching the surface. I do each stage at 90' to the previous one.

My problem is that even with 100 grit emery, this process takes forever. Its ridiculous. Am I not applying enough pressure or doing something wrong?

I've tried using sanding barrels on a dremel which does remove sufficient material, but it removes material so quickly that it leaves the surface fairly uneven, so you need to take more time with the stages using finer emery paper like 400-600grit.

I've heard you are meant to use kerosene as a lubricant when sanding aluminium?

Is 100grit too fine to start with?

I've done a search but couldn't find some specific tips for sanding.

i would start with 80 grit ... you can give greaseless a try it will cut down on your sanding time .... i use greasless then go right to black on a sprial and it shine's like a baby's behind .....

[rotorman]

thanks!

I will try 80 and if that doesn't work 40.

Unfortunately I don't know of any hardware suppliers that do greaseless compounds in Australia

I read something about sanding blocks in some of your old posts?

Now, I can just use blocks of wood - even thought I could make some shaped ones for tight crevices etc....do you attach the paper to the block somehow? Or do you just apply pressure? I can see the paper slipping and sliding around once I apply kero or water to the metal surface.

appreciate your help

[skiddz]

The greaseless compounds will cut your work down quite a bit, but they do cut fast so go slow. As for finding them, Mark the polishing guy is in Australia. Hit him up for some info on where to find supplies. I'm sure he's got all this stuff as he does work for people building show cars..

As for the sanding block/sandpaper issue. Contact cement will do the trick. I use the 3M spray type. Spray a light coat on the block and a light coat on the paper (The smooth side. heheh) and let dry. Once it's dry (not tacky!) press 'em together. No slippin' and slidin'. The paper will peel off with a little effort when it's worn out. Clean the block with laquer thinner to remove any old cement and repeat the process to apply a new piece of paper.

Not sure how kerosene will affect the contact cement if you use that as a sanding lubricant as I sand with water...

Hope this helps!

[mcaswell]

We can sell you greaseless compound and ship to Oz. See http://www.caswellplating.com/international.htm for our international order form and to get a shipping quote.

[rotorman]

Thank you very much for the tips! Its greatly appreciated.

I will check out the international order possibiltiy caswell.

I actually know Mark the polishing guy through car circles, although he lives in Sydney (I think), and I live in Melbourne (pretty far away). I might ask him, but I don't expect him to say as he understandably has a business interest in keeping his suppliers secret. I'm a potential customer of his you see.

[skiddz]

I see... I didn't know of the "relationship" between you.. Thought he might be able to help. Whether he wants to or not is an entirely different matter.. heeheh