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Dec 20, 2012, 09:49 AM
Illegitimi non carborundum
grosbeak's Avatar
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Discussion

Polishing an aluminum spinner


Because there were a few stains and scratches on the aluminum spinner of my recently acquired airplane I decided it could use some polishing. I found few references, the most useful of which was a nine year old thread on RCU: How to polish an aluminum spinner?

For the first round I tried a product mentioned in the thread: Flitz. The tube was $12.99 at my local Home Hardware, but it doesn't take much.



I figured I would polish it until the black oxidization stopped coming off. Half a roll of paper towel and 45 minutes later:



Okay, so apparently you can't get all of the oxidation off. Another entry mentioned the instructions on the Tru Turn website. I post the instructions with a caveat: If you care about good writing like I do, this is going to be like nails on a blackboard: #29 Do you Polish Spinners?

I got some wet/dry sandpaper in 320, 400 and 600 grit and secured the backplate with some wire I had lying around.



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Dec 20, 2012, 09:50 AM
Illegitimi non carborundum
grosbeak's Avatar
Thread OP
fter the 320:



After the 400:



After the 600:



After re-polishing with Flitz:



At this point the finish was duller than when I had started and I began to worry than I had done some irreparable damage. I tried chucking the spinner in my drill press for more polishing but that didn't work well so I won't go into more detail. I figured I had nothing to lose and decided to try power polishing next.
Dec 20, 2012, 09:51 AM
Illegitimi non carborundum
grosbeak's Avatar
Thread OP
For power polishing I found an excellent resource from Caswell: How To Buff And Polish. All of the supplies were at my local Princess Auto:

6" spiral-sewn buffing wheel (x 1)
6" loose cotton buffing wheel (x 3)
4 oz. Polishing compound, Brown Tripoli (x 1)
4 oz. Polishing compound, White Diamond (x 1)
4 oz. Polishing compound, Blue (x 1)
4 oz. Polishing compound, Jeweler's Rouge (x 1)

I mounted the spiral-sewn wheel and one of the loose cotton wheels on my bench grinder; the Brown Tripoli compound went on the former and the White Diamond on the latter.



Afterwards:



The next step were the blue and the Jeweler's Rouge compounds, both onto new loose cotton wheels.



Now, Caswell says the rouge is the finer of the two so I started with the blue and moved to the rouge. I took another look at the packages, however, and the compound manufacturer shows the blue to be the finest. So I finished with the blue. The final result:



.....

Reflections (pun intended) on the polishing process:

The Flitz method:
Good results and, once you realize that all of the oxidation can never come off, fairly quick. At $12.99, Definitely the cheapest.

The Tru-Turn method:
Poor instructions and results to match. About $15 in sandpaper - and you still need the Flitz.

The power polishing method:
Quick and easy. The most expensive, though, at about $45. And that's if you already have a grinder.

In conclusion, I'd recommend the Flitz, at least to start with. Lots of folks recommend Mothers Mag & Aluminum Polish so that's certainly an alternative. I'm not sorry I tried all three methods - I sure learned a lot and hopefully some of it will be helpful to others.
Dec 20, 2012, 10:33 AM
Registered User
jhaywood's Avatar
the last one that I did, I used 400, 600, 800, 1200, 2000 then starting polishing with flitz type compounds finished with Never Dull
Dec 21, 2012, 02:45 AM
Wake up, feel pulse, be happy!
Piece's Avatar
Neat! I've actually been griping about this for the past three days over my Slipso400 spinner.

I bought a spinner from HobbyKing for $3.29 as an experiment, and it turned out to be real nicely polished and ran perfectly true even up past 35k RPMs. I was happy with it... Until I stripped out the collet threads mounting it a few days ago

So it was back to the incredibly good-quality but dull-finished MPJet spinner. I think maybe I'll try polishing it with this method as I already have some Dremel polishing compound which seems to work for hand-polishing pretty well. I used it on a knife blade awhile back with good results.

I guess the only nagging question is why am I gonna waste time polishing something nobody can even see at 160mph?
Dec 21, 2012, 08:35 PM
Illegitimi non carborundum
grosbeak's Avatar
Thread OP
After lots of feedback from the forums on which this topic was started, I decided to try a fourth method using much finer sandpaper and Mothers Mag & Aluminum Polish instead of Flitz.

At my local Canadian Tire I found 1000, 1500, 2000 and 3000 grit sandpaper and the Mothers polish. With a pair of Nitrile gloves, some soapy water and some polishing towels I was ready to go.

After the 1000 grit:



After the 1500:



The 2000:



The 3000:

Dec 21, 2012, 08:48 PM
Illegitimi non carborundum
grosbeak's Avatar
Thread OP
With the sanding done it was time for the Mothers Mag & Aluminum Polish. I read the instructions carefully.



After the first polish:



After the second:



I'm not sure if there's merit to polishing it more than once or twice - opinions are welcome. In both cases the terrycloth towel came away black and I buffed the polished area with a microfibre cloth, going over it repeatedly with a new spot on the cloth each time until the black no longer appeared.

So...

The fine sandpaper and Mothers polish method
This took a little over an hour and gave the best results of all. Approximately $17 for the sandpaper and $9 for the jar of polish.
Dec 22, 2012, 09:46 AM
Registered User
My method on large spinners......
Mount spinner on engine that is already in plane.
Start motor and at a idle hold polishing rag to spinner going up to prop and back to front.
Works every time.
Dec 22, 2012, 08:10 PM
Illegitimi non carborundum
grosbeak's Avatar
Thread OP
Quote:
Originally Posted by Jim409
My method on large spinners......
Mount spinner on engine that is already in plane.
Start motor and at a idle hold polishing rag to spinner going up to prop and back to front.
Works every time.
Sounds a little dangerous...
Dec 22, 2012, 08:13 PM
Wake up, feel pulse, be happy!
Piece's Avatar
I used the Tru-Turn method to polish my little 30mm MPJet spinner last night. Definitely looks better than it did, but it's not really a perfect mirror polish. I probably could have gotten it looking nicer, but the thing is the size of a gumball and even I can't see much of a difference from five feet away hanging on the wall. The whole plane is barely visible in flight at all.

Soooo..... Time spent? ~ 1 hour. Time wasted? None
Dec 23, 2012, 02:42 AM
Leroy G.
Leroy G's Avatar
Polishing is the easy part as you have shown but keeping it that way is another matter.It's going to oxidize, thats just the nature of aluminum so clear coat it with a good urathane to keep the beauty you just put on it. Those pretty alloy custom car wheels have the treatment, just look at them. Leroy


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