Newb questions. Foggy finish. Pimpled/pitted aluminum wheels.

[posneg]

Hey everyone,

So today I just got my aluminum polishing kit and I thought my dreams of shiny-metal-magnificence were finally going to be realized. Let me sum up my feelings with the following emoticon.

After doing some research in these here forums I "think" I've narrowed my problems down to no less than six possibilities.

A. I haven't used a low enough grit sandpaper to get rid of the pits.
B. I didn't use any kind of water with my wet/dry sandpaper.
C. I did a cut and color stroke in the same buffing session.
D. I used a too-slow drill.
E. Not doing any kind of cleaning except for a simple rub down with water.
F. All of the above.

I checked with the teacher and the correct answer is E.

The lowest grit I went to was 220. I thought it'd be enough but after several passes the pits can still be seen after "polishing". My research tells me I should go all the way down to 80 grit but I'm afraid that might cause more problems.

I didn't use any water or, as I've read, some kind of magic dish soap concoction. What's the formula for that stuff and why is it better than plain water?

When I was buffing I went in and out of the lip of the wheel as I went back and forth. As if I were cutting grass.

According to Ryobi's website my drill goes up to a whopping, get this, 100 RPM! Using the 4" wheels that come in the kit I'm doing 100 RPM (probably less, really).

In between stages I did zero cleaning except to simply wipe the compound dust off the wheel.

But after all this I do think I was using the right amount of compound because I never had the thick build up that I've read about.

One thing I noticed is that after using the black compound with the sisal wheel I move to the brown compound with the sewn wheel. But the problem is that a lot of the scratches from the black compound+sisal wheel are still visible. Some of them go away but the majority of them are still there.

Last thing I should mention is that my sandpaper grits are 220, 400, 800, 1000, 1500. After reading the forum it seems that I don't need to go higher than 600 which I kind of figured out myself since even the 800 grit seemed smoother than the black compound+sisal wheel.


I've included some pictures of the results.


Any and all comments are welcome and let me know if I've left out any pertinent details.

[mpierich]

I wouldn't go down to 80-grit...it might be fast but it'll leave beaucoups scratches to get out. I always start with 120, even on sand-cast parts.

Wet sanding might help a little when you get to 220 or above. The soap thing is sort of overkill...it's used when wet-sanding paint finishes... but it can't hurt, just a few drops per gallon of water is plenty. Wet sanding will definitely make your sandpaper last longer. You don't say how you're doing the sanding (by hand?) but you might want to try greaseless compound in 120/220/320 grits.

The cleaning between grits and compounds is very important. When you get to the polishing compounds, brake cleaner, lacquer thinner or acetone (etc.) is needed to get all the grease off.

As far as your results, I would say that the biggest flaw in your ointment is the drill speed. You need to build up heat for the compounds to work right. Also, even a Ryobi will burn out with continuous use. If you can, maybe get a cheap drill with a higher speed. Some folks on here use high-speed angle grinders with buffing wheels, but in my opinion that's a little dangerous since most wheels aren't rated for that 20,000 - 35,000 rpm speed.

[baz]

i would probably do 120 through 600 grit the forget the sisal wheel , use a tight stiched wheel (the ones that have a row of stiches every half inch)and a higher speed tool . your biggest problem is notonly the tools .
if its your first part you polish , give yourself a chance to practice and everything will be ok.

mpierich ,you slipped in a french word in there (BEAUCOUPS) . are you french ?

[posneg]

Are there any pages on the forum or Caswell's site that recommend tools?

How about this one from Sears's site? http://www.sears.com/shc/s/p_10153_12605_00926833000P

Regarding cleaning: even if there doesn't appear to be any material leftover after I finish a step I still need to clean the surface? Is it invisible grease that is leftover? Or maybe I'm just not seeing any residue because my drill is not creating the proper level of heat.

[posneg]

Thanks for the info baz.

[mpierich]

Originally Posted by baz

...mpierich ,you slipped in a french word in there (BEAUCOUPS) . are you french ?

Haha, knowing where you're from I figgered you'd catch that.

Nope, not a drop of French in me...but some of my buddies who went to 'Nam (and made it back) picked it up over there, and they got me saying it too after a while.

[baz]

Originally Posted by mpierich

Haha, knowing where you're from I figgered you'd catch that.

Nope, not a drop of French in me...but some of my buddies who went to 'Nam (and made it back) picked it up over there, and they got me saying it too after a while.

haaaah,that explains it

[posneg]

To recap, it was recommended to me to (1) get a faster instrument, (2) clean the surface between stages, and (3) use a lower grit sandpaper, possibly the greaseless compound.

Since I don't have the greaseless compound yet and I'm pretty impatient I got a new drill (2500 rpm) and some paint thinner for cleaning and tried again.

However, this time my results look just like the pictures above. I thought that even without resanding the surface I would see at least a SMALL improvement in the finish. But I haven't seen anything.

Any other tips?

I can understand that for a really good finish you need to have proper sanding and cleaning between stages, but is really not possible to get a better finish than what I'm already getting even with the improvements I made?

[baz]

Originally Posted by posneg

To recap, it was recommended to me to (1) get a faster instrument, (2) clean the surface between stages, and (3) use a lower grit sandpaper, possibly the greaseless compound.

Since I don't have the greaseless compound yet and I'm pretty impatient I got a new drill (2500 rpm) and some paint thinner for cleaning and tried again.

However, this time my results look just like the pictures above. I thought that even without resanding the surface I would see at least a SMALL improvement in the finish. But I haven't seen anything.

Any other tips?

I can understand that for a really good finish you need to have proper sanding and cleaning between stages, but is really not possible to get a better finish than what I'm already getting even with the improvements I made?

hard to say from the pic . first are you sure that if you had a clear coat on the lips it is completely removed . how much sanding did you do with your 220.
you have to really sand down all the imperfections not just scratch the surface , this is a mistake lots of beginners will make .a good sanding with 220 ,400,600 followed by the buffing , make sure you have enough compound on your wheel then apply enough pressure to generate friction heat , clean the buff often ,if you follow these steps you should get a decent finish without the use of greaseless. (but greaseless will save you tons of time compared to hand sanding and will get you a nicer finish .

[posneg]

Thanks for the reply.

It's hard to say. As far as I can tell, in my limited experience, I've done a lot of sanding. A friend suggested the same thing; that a clear coat had not been removed. How thick is a clear coat and does it actually penetrate into the metal? I think it's gone but I don't know how to be sure.

When I'm sanding I see a medium gray dust. That could be from the black material of the sand paper and from the metal of the wheel itself. Should I be seeing a different color? Or rather, if a clear coat is present will it look different?

It seems pretty clear that something is going wrong. I just hope I can figure it out before I invest any more money.

Regarding the heat of the wheel, I've never felt anything more than a slight warmth from the wheel even after polishing for over a minute. Should it be hot or really warm? And this brings up another question, how long should I be polishing on each stage? I generally stop once I stop seeing any kind of improvement.


Let me describe a little bit more what I'm observing.

I use the sisal wheel* with the black compound and I can see that the surface gets roughed up pretty good (but obviously it's still smooth to the touch). Then I use some paint thinner and a paper towel to wipe the surface down. I wipe it several times (is that necessary?) until the paper towel is relatively free of residue. Then I used the sewn cotton wheel with the brown compound. I can see that the majority of the scratches from the sisal wheel go away but the improvement comes to a halt and there are still many scratches left. Even if I buff for a few minutes it does not make any difference. I'm assuming that by the time I get to the brown compound I should not be seeing ANY scratches. Is that correct?


* That's another thing, I don't have any clean wheels or any means to clean the wheel (does soap and water work?) so I had to stick with my sisal wheel with the black compound instead of using a clean sewn cotton wheel for the black compound.