Best Way to Polish Aluminum Tubing? - DIY Chatroom

Mod Dig · 07-10-2009, 02:41 AM

Hi all,

What method would you suggest for polishing 1 1/2 inch OD aluminum tubing? I have 2: 7 foot and 1: 6 foot lengths (20 feet total).

I found a couple methods here:

http://www.ehow.com/how_4491972_poli...or-finish.html

http://www.ehow.com/how_4546581_fini...or-finish.html

I'm looking for an inexpensive and quick method. Also would it be difficult to do this by hand, and should I get some tools like the orbital sander mentioned?

Thanks!

Maintenance 6 · 07-10-2009, 02:58 PM

An orbital sander won't help much for tubing. This is mostly hand work. Start by dry sanding with some 280 grit paper or whatever it takes to get the extruding marks out of the stock. Then go to a wet type sand paper and wet sand using finer paper in steps until you get down to 1200 grit. Then go to finer steel wool and then to a very fine scotchbrite pad. Themn you'll have to go to rubbing compund and finally to fine polishing compound. You'll need to clear coat with something to keep the aluminum from oxidizing. Be aware that some alloys of aluminum don't accept a polish real well. A motorized buffer will do more for you than a sander.

Mod Dig · 07-10-2009, 07:24 PM

Thanks for the reply. The tutorials I posted each have different steps. Is there a reason for this? The tip about clear coating is a good one. The second one has that tip, but the first one ends in buffing using cutting compound. Also, the first one uses 6 grits of sandpaper, while the second one uses only 3!!!

Maintenance 6 · 07-13-2009, 08:57 AM

The more steps between grits of sandpaper, the less time you will spend on each step. For example, if you jump from 400 to 800, it will take more labor to get the 400 grit marks out of the stock. If you jump from 400 to 600, it will go faster. Then go to 800. Same thing. I've never used all the dish washing liquid paint thinner, etc. Wipe any oils off with a solvent that doesn't leave a residue, like laquer thinner, before you start. Dry sand to remove any mill scratches first. This is a very labor intensive process. If you miss any scratches from a previous step, you'll end up starting over, at least in some local areas. Plan to get black dirt in every pore of your hands as aluminum is dirty to polish or else wear rubber gloves. Your last step will involve polishing compound or rouge. Use one that is made for cutting aluminum. Aluminum protects itself from corrosion by forming oxides on it's surface. Oxygen combines with salts in the aluminum to form this barrier. These oxides begin to form on the surface of aluminum immediately, so a clear coating is needed to prevent it from dulling up when you are finished. Touching the polished surface with your bare hands will leave marks, so handle it with a lint free cloth until it's coated. Try a small area to be sure your alloy will accept a polish before you invest a lot of time.

Mod Dig · 07-15-2009, 03:40 AM

Thanks! That's very helpful information!

Aggie67 · 07-15-2009, 07:43 AM

Have you tried getting a price for electropoishing? Around here, those pieces wouldn't be all that expensive to finish. And it comes out looking like a mirror.

Mod Dig · 07-16-2009, 12:27 AM

Hey there, thanks for the reply. Are you talking about electroplating? And yeah it's expensive, partly due to the length of the tubes. I think there's only 1 place around here (east bay, CA) which has the right tank or whatever. How much does it cost over there? Maybe I can get them shipped somewhere. It certainly would be easier if it's not too pricey.

Thanks!

Aggie67 · 07-16-2009, 10:09 AM

Quote:

Originally Posted by Mod Dig

Hey there, thanks for the reply. Are you talking about electroplating? And yeah it's expensive, partly due to the length of the tubes. I think there's only 1 place around here (east bay, CA) which has the right tank or whatever. How much does it cost over there? Maybe I can get them shipped somewhere. It certainly would be easier if it's not too pricey.

Thanks!

Not electroplating. ElectroPOLISHING. The lingo in the trades is "EP", as in "does this need to be EP'd." And the finish grades are measured in RA, like 15 RA, 20 RA, 32 RA. When you buy metal from a mill, it's typically 50 RA. When you EP it, the RA number goes down by about half. RA is a measure of surface roughness.

I've had pieces like that done for $75. There's a place in Kearny NJ I use called Haward Co. Great guys, great work. For some of our customers, we fabricate high purity tubing components, and they require electropolishing. The items are used in the biotech industry (injectibles, pharma, etc). The parts come back with a mirror finish, like chrome.

Mod Dig · 07-17-2009, 04:41 AM

That sounds cool!! I'll look into it over here. Do you know what would be the cheapest thing whether it's black steel, or this electropolished stuff (or something else), since I'll probably have to get more tubing in the future...and also where to get it if shipping isn't too much (unless it's better just to pick it up locally)? I'm not sure if I care whether it's steel or aluminum, but I do want it to look nice and it will need to be 1.5 inch OD so the drum rack clamps will fit on.

Thanks!