Alternatives to hand polishing aluminum? (Moved from Swap)

Sorry for the repost. I inadvertently started this in the Swap forum but don't know how to move it...

I'm about to start in polishing the engine covers, lower fork tubes, grab rail, etc, on this 650H. On my last bike I did this all by hand with 320-1500 grit paper plus penetrating oil, then billet metal polish. In the end, I was very satisfied with the results. This process has the advantage of allowing you to be pretty precise, but it's slow and tedious.

Maybe it's the only way to do it, but I thought I'd ask if there are alternative methods that use a wheel or power sander of some sort. I know that the super fine, mirror-like finishes are achieved by using polishes on different types of discs at the end of the process, but I'm not really planning to go that far. This won't be a show-quality bike where everything is perfect, so I'll be happy with ~1500 grit level of finish.

Thanks!

 

look at http://www.caswellplating.com/buffs/index.html
and a cheap harbor freight grinder and your set, no need for sanding just use black or brown compound.
look at "shank mounted buffs" for the corners

 

Re: Alternatives to hand polishing aluminum? (Moved from Swa

Thanks, Pollock. Just a couple more details for clarification...

1) Should it be a three stage process as described on this page and, if so, do you change compounds with each stage? (I really don't know anything about buffing.)

2) How big a motor on the grinder and what size pads? I've got a cheap 1/2 hp 6" 3450 rpm grinder, but it doesn't have much power with the grinding wheel and wire wheel that are on it.

 

A buffing wheel mounted to a drill press does a fine job. My floor drill press can run different speeds so its ideal for polishing. I have different wheel and compounds ot achieve any lever of finish you want. Most all the wheels and compounds were purchased at the local home center.

 

That sounds interesting. Must make a mess of your drill, though, doesn't it? I was thinking of something I could clamp to a table or Workmate bench so I could take it out in the yard and keep the shop and garage from getting full of compound.

How long do the wheels last, by the way? Also, should you keep each wheel dedicated to a single grade of compound?

 

It doesn't make much mess, just run the vacuum when I'm done. Yes I do have a wheel dedicated to each grit of compound. It does take awhile to wear one out.

 

Re: Alternatives to hand polishing aluminum? (Moved from Swa

6" wheels will work, but I prefer 10" wheels.

You do NOT want to use different compound grades on the same wheel. You would regret it the first time you tried using color compound on the same wheel you used tripoli on.

Compound colors:
Black=Emery
Brown=tripoli
green=aluminum
White=color
red=rouge

I wouldn't use black unless you have some major pitting going on. Tripoli works just fine to get out small pinholes.

Sanding with 240 to 320 grit paper is the actual "polishing" step.

Cloth wheel polishing is actually referred to as "buffing".

Tripoli will make it shiny, then use color to make it "bright", then use rouge to make it "mirror".

Keep in mind not to get the part too hot, you can actually pull the metal if you do.

Also take care around details, such as "Yamaha" on the engine cover. It is VERY easy to pull the corners of the lettering.

Buffing machines work the best, because they have a higher RPM, and usually more HP.

But grinders also work, as well as drill presses and hand drills. Just remember the slower the RPM, the slower the process.

Also check into using a Dremel (or equivalent) for very small parts you can't hold onto.

A decent machine will run you about $100, a good machine will run you about $300.

One more tip, the upward motion of the part on the wheel is the "cutting" stroke, and the downward motion of the part on the wheel is the "cleaning" stroke.

EDIT:
I should also add that blue compound is used for buffing plastics, but I don't recommend this unless you have years of experience.

 

Re: Alternatives to hand polishing aluminum? (Moved from Swa

i don't do any sanding, that's like work but i have used a file to clean up road rash. sanding is kind of like wet sanding for paint, to get a perfect surface then make it shine with the wheels, i settle for shiny with some imperfections that are shiny
a small grinder like that is going to take a long time to work with, one reason is a 6 inch wheel is the max and it doesn't come out far enough and your always running into the motor so you have to work around that
sometimes you can't
if you can get a old furnace motor or something and put one of
these on it with 10 inch wheels your in business

 

My "power polishing rig" is my Milwaukee 1/2" electric drill mounted upside-down in my Workmate spinning 4" buffing wheels I got at Home Depot in some cheapo $6 "buffing kit."

I set it out in the driveway so I don't spray the whole garage with buffing clag.

Personally, I'm not a big fan of a complete "mirror" finish-- so I do the very final polishing by hand.

Don't forget to strip the old clear coat first; "Aircraft" Paint Remover (available virtually any auto parts store) works the best.

 

I have found that a wire wheel does a good job of stripping the old finish off. It's very messy so I did it outside. It can leave whorls though, so if you're going for the mirror finish you'd have to be careful. I was going for more the brushed look, so it was fine for me. I didn't try to get every scratch out, and this was faster than sanding off the clear coat. I used a drill.

 

Re: Alternatives to hand polishing aluminum? (Moved from Swa

THANKS for all of the details. Amazing, but I think I'm starting to catch on... A couple more clarifications:

Adapting electric motors, using grinders, drills, etc
I thought I might be in luck with an old furnace motor I've had laying around for years, but it's just too slow. I assume that there isn't a shaft extender available for a grinder because of the thread shaft? And I assume that a 6" grinder might really not have enough power to put an 8" wheel on it?

Compounds
Brown/Tripoli compound should go on a spiral wheel, right? Fitz's suggestion to strip the lacquer off first might not be necessary if I used the black compound on a sisal wheel, right? When I do the lower forks tubes, might I not want something more aggressive anyway for down around the bottom where it's rougher?

Cover details
I've been wondering about buffing around the "Yamaha" detail which tskaz mentioned. I assume I'll have to repaint those embossed letters when I'm done? Also, will the buffer destroy that round rubber bead on the clutch cover?

Thanks, guys!

 

even if the motor seems slow the 10 inch wheel due to it's diameter is plenty fast enough, a grinder with a 8 inch wheel will work but you cant push too hard. sometimes you can find a part after a slower wheel grabs it, with a faster 3450 rpm motor they go into orbit
strip the clear or it melts off the part and gets on the wheel and makes a mess, then you have to clean the wheel and that shortens it's life, it gets smaller. sisal wheels are aggressive
that rubber ring doesn't stand a chance

 

Well, the motor says it runs at 1750 & 1140, but I think I've only got one speed. The three wires (white, orange, blue) hook onto a switch or relay mounted on the motor. I'm assuming that one is the high speed wire and the other is the low speed, (although I suppose one could be a control wire?). Right now I can get it run on the orange and white wires.

The formula I saw on the Caswell site said you want 3600-7200 SFPM. and that you should divide your wheel diameter by 4, then multiply it times the rpm of the motor. If I'm running a 10" wheel at 1750 rpm then that's 4375 SFPM, but if I'm at 1140 rpm it's only 2850.

And are you saying that a sisal wheel would destroy the rubber bead or that a spiral wheel would too?

 

I use my 8" grinder for polishing but would much rather have a buffing machine. The biggest advantage to the buffing machine over the bench grinder is the length of the spindles. The polisher has much longer spindles which makes it easier to position the work piece.

The compounds used on the polishing wheels is the least of your worries when polishing indoors. It is all the little pieces of cotton threads that break off as you polish. They can just about fill the garage with fibers so run a vacuum close to your work to suck 'em all up.

Here are a couple valve cover pics showing machine polished valve covers on my SilverWing.

Loren

 

I notice that you've got a small wheel on a pneumatic die grinder. Can you slow that down enough so that you don't have to be super careful?

 

i use the heck out of my buffing machine i run a 8 inch on 1 side and a much smaller on the other side helps in getting into tight areas. The hardest thing i did was my maxim x rear wheel. It has machine lines that had to be sanded out. I ended up doing it by hand looks good. Need to buy another hand buffer/grinder

 

Take the clutch cover apart, and remove the insert that the "rubber ring" is part of. You could also buff the inner part to a different degree than the outer case if you want.

The original lacquer coat is some TOUGH stuff. Quite often, you'll find yourself trying to buff "over" it; that won't work, and a wire brush is way too destructive.

If you want to do it right, strip the lacquer first.

 

Ok I'm going to ask a question that may seem stupid (I know, the only stupid question is the one that isn't asked), Are the wheels on the Maxim-X lacquered?

 

Is there anything to put on the aluminum as a final step to protect it? Unfortunately all the work I did was ruined when I had to leave my bike outside for a year - covered, but still outside through a good ol Canadian winter/spring.

 

any kind of buffing wheel will tear up that rubber ring
remember caswell's numbers are for a pro, anything you do with a wheel is going to be way faster than by hand.
i've seen claims for stuff truckers use that says it protects for a long time but never tried it, if i get lazy and something gets dull again rubbing and polishing compound bring it back pretty quick

 

Re: Alternatives to hand polishing aluminum? (Moved from Swa

OK, so I went and picked up some supplies to try a little test without making a real big investment. I picked up a polishing kit from HF with various small cotton shank wheels and felt bobs that included black, brown, and green (for SS?) compounds. I also got a spiral-sewn 6" wheel which I mounted on my 1/2 hp 3450 rpm bench grinder. I applied the Tripoli compound to that and started on my pickup coil cover.

The cover really wasn't scratched up per se, but parts of it were darkened and "mottled" the way these things get. With the brown compound it took a long time to get that out. In fact, I really couldn't get all of it out. As I expected, it wasn't hard to really slow down my grinder. I then clamped my 1/2" 3600 rpm drill in the Workmate and put some black compound on a 2" wheel (the stiffest that came with the kit). That cleaned up what I couldn't get out with the Tripoli. I then finished up using brown compound on a cone-shaped felt bob.

The results are better than I got using the 320-1500 grit sandpaper method. I put some billet polish on by hand at the end, but I can't really tell if that made much of a difference. (It does provide some protection, though, eman.)

I'm honestly not real sure if it was actually faster than hand sanding. If I had another 6" wheel for the black emery compound, I think that would speed it up. The results are superior, however.

Right now, HF has a 6" buffer 1/2 hp buffer that can be bought for $35 with a 20% off coupon. I assume the power will be comparable to my grinder. I'd sure like to have bigger one, but it's so dang cheap that it might be worth it anyway.

As for removing the lacquer, I have been stripping that off previously so I'll just continue with that method.

 

As for the Yamaha lettering, if you do it right then you won't need to repaint (unless you want to).

What I'm referring to when I say "pull" the letters is:
If you get too close to the letter when buffing you will actually "buff off" part of the metal and it will look like, well, like you sanded some of the metal off, because that's what you are doing. It will leave a valley in the metal at the corner of the letter. Same thing goes for holes.

The way to buff around these is to learn where the extreme edge of the buff hits the part, and just let the buff lightly "kiss" the metal in that area.

This takes years to master, so go slow and be careful, but you will end up pulling something, somewhere along the line, just don't let that shy you away from buffing.

Along the same lines, don't keep the wheel in one spot too long, or you will "burn" the metal. This is where the metal actually starts to get hot enough to flow the metal as it is being sanded by the wheel. The only fix for this is to polish (sand) the metal, then re-buff it. It is more of a problem when buffing zinc or copper as opposed to aluminum and steel.

And that brings me to my next tip:
Wear gloves when buffing!

Polishing the metal doesn't get it very hot to the touch. I have run thousands of parts through our shop and never wore gloves when polishing.

But buffing does get the metal hot. I have run thousands of parts through our shop, and only made the mistake of not wearing gloves ONCE!