2010.07.19 Monday - Polishing Aluminum Guitar Stomp Box Pedal

Funky headache when I woke up this morning, probably from the taco b last night.

Work went by rather quickly. Also got some gym time in. Pretty successful day.

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Yesterday, I spent a good chunk of hours grinding away at medal, putting some blood sweat and tears into my DIY guitar pedal. Actually, I spilled no blood, and I only cried when I saw the final product :-P I got the 250+ kit from B.Y.O.C. (actually was a gift for my b-day) which comes with a bare aluminum enclosure.

My goal: Polish the top and bottom of the stomp box to (near) mirror finish.

Tools needed for the job:
-Something that you want shiny (needs to be non-anodized)
-Wide range of sandpapers (I personally had 200, 320, 400, 1000, 1500, 2000, and 2500)
-Hard surface, like a chunk of wood or some relatively flat paneling
-Water
-Gloves
-Metal Polish (I used Mother's Mag & Aluminum Polish)
Optional:
-Dremel high speed rotary tool
-If you are Dremel-ing, highly recommend safety glasses

So how exactly does one go about getting some metal from dull to shiny? Lots of patience and elbow grease. I've done a little bit of searching around the internet for information on how to do something like this, but a lot of tutorials expect you to have big fancy tools. I don't have that, and I don't have the space for some of that stuff.

Here's the basic process.
1. Clean off the surface you'd like to polish with water and soap
2. Starting with the lowest grit, then gradually working up to higher grits:
A. Place sandpaper on hard surface, abrasive surface side up
B. Wet down the sandpaper
C. Place object with surface you want to shine against the sandpaper
D. Move object back and forth until all areas of surface appear to have the same "grain" and are smooth
E. Repeat all parts of step 2 EXCEPT each time you start using a new sandpaper, rotate your grinding motion (or rotate the piece) by 90 degress. Also be sure to rinse everything often.
3. Clean off everything by rinsing with water
4. Place some metal polish on the freshly sanded surface, and polish away.

There are a couple reasons to do the 90 degree rotation between grit levels. First off, if you visualize the surface as mountains, you grind away most effectively if you cut across the peaks and valleys. For instance, if these vertical lines are the peaks...
| | | |
| | | | <= grind them away this way =>
| | | |

Another reason to do the 90 degree rotation, you can actually see the difference between each level of sandpaper. You can see all the spots that have not been ground away from the previous grit. I'll show you in a little bit.

Now, the pictures. First up, this is what I started with. This is pretty much untouched aluminum. I have no idea how this was machined or created, but it looks pretty terrible. Even if I was going to paint it, I would highly recommend doing some base sanding, then priming, then painting, then clear-coating... but we will save that for another blog :-D

Here are all the pieces of sandpaper I had. I prefer having longer rectangular shaped pieces, and just grinding away lengthwise. I have (pictured from left to right) 200 grit, 320 grit, 400 grit, 1000 grit, 1500 grit, 2000 grit, and 2500 grit. This is just the back side of the paper. If I were to do this over, I highly recommend starting off with a lower grit (100 or 150), and not doing a jump from 400 to 1000 like I did (at least add a 600 or 700).

Here I tried to show that yes, the paper needs to be wet. It's called wet-sanding. Not only does it help keep metal dust particles from flying into the air, but it actually sands a bit more uniform since the particles can just wash away.

This is the results of the first level of sanding (200 grit). This part took the longest. Essentially, I converted some random gross surface to a uniform surface. You will want to spend the most time in the lower grits since they are most abrasive (they do more to the surface). I promise you, take your time in the first couple stages of sanding, and it will pay off later.

The next couple pictures show the 90 degree rotation I was talking about earlier. It's kinda hard to get a picture of this, but hopefully you get the idea. With the 200 grit (pictured above) the "grain" of my sanding was left-and-right. When I started the 320 grit, I started grinding away up-and-down. This hopefully shows how you slowly grind away at the peaks and valleys left behind by the other lower grits.



I'm pretty sure my camera started crapping out, and writing over it's own pictures or something. I've taken over 10k pictures with it. Anyway, this next picture is what things looked like after completing 400 grit. I did 200 grit with left-right orientation, then 320 grit with up-down, then 400 with left-right. Also, you can see that the metal is still a bit wet, but the lines from the "grain" are starting to become less prominent.
Here are the results after 1000 grit (up-down). You can see that some areas look a little off. I think the jump is too large between 400 and 1000, since this step took me quite a while, and didn't come out as well.

Back to the left-right with 1500 grit. You can see some micro-scratches in the middle. These happened because of the way I pulled off the piece from the sandpaper (see how tiny things can make a big difference now). Don't worry too much about micro scratches, remember we have the polish on our side.

And again, my camera didn't keep all the pictures, but here are the results from the left-right 2500 grit session. Notice that you can make out a blurry reflection, and can only barely see the groove from the sandpaper. If you took your time, you will have noticed that the lower grit sandpaper takes a long time, the high grit sandpaper takes barely any time. Also, the high grit sandpapers make a lot of black water rather quickly, make sure you keep that paper clean by rinsing often.

Here is the metal polish I ordered. I think the Texas heat heated it up pretty well, because when I first opened it, it spilled all over my pants. Not cool. Later when I used this, it was more of a paste. It worked well regardless of state it was in.

I did not take any pictures of the polishing process. I personally used a Dremel tool with one of the polish heads. I used it at the slowest speed possible too. The polish goes from white to dark-grey/black when it is doing its job. If this doesn't happen, something is wrong (that is what the container says :-) ). Things get really messy when you fling polish everywhere, so be careful and use eye protection. Enjoy the final pictures... ooo shiny.



If you have any questions, of if you need me to clarify something, just leave a comment. Also, I take no responsibility if you hurt yourself, or destroy your clothes or guitar pedal.