(Topic ID: 313597)

Restoring Speaker Panels (the hard way)

By radium

1 year ago



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  • 3 posts
  • 2 Pinsiders participating
  • Latest reply 1 year ago by radium
  • Topic is favorited by 7 Pinsiders

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    #1 1 year ago

    Fixing scratched ugly speaker panels is hard. I've tried many times over the last ten years and can never get it right. There is no easy-to-follow guide for it that I've seen. This year I got obsessed, and after a half dozen attempts finally have a process that works pretty well.

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    While it looks great in the game, it's still not perfect and if you zoom in you can see tiny sanding marks are still in it. These marks are from grits over 1500. I think I know how to avoid them next time but this is good enough for my F-14 and I'm sick of sanding this thing.

    If you want to restore your speaker panel, your best two options are:
    1) buy a reproduction if it is available
    2) shoot a coat of 2PAC clear on your original

    Seriously, these are much easier options. If you still want to do it the hard way, I will post what I did in the hopes that you can avoid my mistakes and maybe someone smarter than me will tell me how to improve further. Hopefully there is some easier way to do this!

    Obviously you have to sand the plastic to remove all scratches of every size. I've done lots of woodworking, so I thought this would be easy. Sanding plastic is different because you have to thoroughly sand every single grit to make sure you are removing every single scratch from the previous grit. You must not miss a single scratch or it will be visible at the end.

    Before I get into it, let's look at a bad attempt. I started out approaching this like wood. I bought a bunch of sandpaper of a bunch of various grits and sanded "a good bit" with each one. After a few grits I had a big crap sandwich. As you can see below I have a trainwreck of various scratches of every size grit I used, plus there are lots of swirl marks and haze. In woodworking, this would be fine and I'm just trying not to oversand and remove too much material, but that's not how it is with plastics. You must remove EVERY scratch before continuing to another grit.

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    Around this time I went to a local automotive paint store and started asking questions. They were helpful, although they didn't know much about polishing acrylic beyond motorcycle windshields. Close enough.

    Sanding Process:
    1) Tape off the score windows on the back of the speaker panel with blue painters tape so they do not get scratched
    2) Clear off a flat surface somewhere to work on. Remember this will get wet. I used the F-14 playfield glass on my workbench with some plastic sheet on top.
    3) Make sure this entire area is clean.
    4) Put the speaker panel on there. You can tape it down with blue tape so it doesn't move around while sanding.
    5) Machine sand thoroughly with the lowest grit you need to use in order to remove your scratches. I started with 220. The lower grit you use, the more sanding steps you will need... start as high as you can get away with.
    6) Clean the plastic with water and wipe clean. Clean the entire work area as well, removing dust or water from wet-standing. This is important. Wipe with a clean paper towel, then blow the plastic dry with compressed air. Inspect with a bright light to make sure the large scratches were removed. If there is haze from wet sanding, clean again with Novus 1 and a new paper towel. I found my phone camera took good pictures at an angle that would show the scratches well, so try that.
    7) Get a flat sanding block and load your next grit sandpaper on it. From 220 I went up to 320. At these low grits I sanded dry, but I would switch to wet sanding as soon as possible (probably at 400).
    8) If you are wet sanding, spray a coat of water with a little dish detergent over the entire plastic. Spray your sandpaper too.
    8) Now sand IN ONE DIRECTION. Either left-to-right or up-and-down. Sand only in that direction. Use firm pressure and sand thoroughly. If you think you are done sanding, keep going because I bet you're not done. When your hand is numb, clean the plastic well per step #6.
    9) Carefully examine your work. If you sanded in one direction, you should see consistent scratches going only in that direction. There should be no other visible scratches going in any other direction. There should be no swirl marks from machine sanding. If you see anything other than scratches going in one direction, that means you have not removed the previous grit's marks and you need to keep sanding! You may need to clean/sand the same grit several times.
    10) Once you are sure, you can move to the next grit. In this example we are going from 320 up to 400. Since I have wet paper for 400, I will start wet sanding at this point. Repeat steps 6-9 but SAND IN THE OPPOSITE DIRECTION you used for the previous grit. If you were sanding up-down, then sand left-right. The reason you are switching directions is so that you can examine the plastic and see if all the scratch marks from the previous grit are really gone.
    11) Now keep repeating this for each grit, switching directions each time. After each grit you should see scratches going in one direction only!
    12) At grit 1200 I decided to switch to machine sanding. Personally I think this was a mistake because I was not able to get as thorough results (probably because I wasn't sanding some grits enough even though I thought I was) and I could not tell one grit's scratches from the last. When machine sanding, I found it is very important what pads and products I used so I will discuss that separately below. To machine sand, basically clean as per step #6 and spray per step #8, sanding thoroughly until all previous grit marks are removed, clean well, dry, and examine.
    13) I stopped sanding at 5000 grit. Is this enough? Too much? Hell if I know, but I figured I'd go hog wild here.

    After you reach your target grit, you can polish. This is another area I do not know much about. Should I use compound and a wool pad? Or machine polish with a foam pad? I still do not know what is correct or how to choose. At the advice of the auto paint store, I went with polish and foam. Both are mild abrasives but polish is even... milder.

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    Polishing Process:
    1) Clean everything thoroughly, including your work area.
    2) Dry everything with compressed air.
    3) Apply polish to the plastic. I used 3M 39062. I just squirted some on. I used about a tablespoon. I used just enough that it seemed to coat the plastic thoroughly while polishing.
    4) Put your polishing pad on your polisher. Use the pad that matches your polish. Some 3M products have color-coded caps, so I knew my 39062 polish needed a blue polish pad (3M #05733).
    5) Put your face very close to the polishing pad and look at it. IS YOUR POLISHING PAD CLEAN? This is important. Make sure no trash or dried polish is in the pad or this can introduce scratches and make you cry.
    6) Before you start polishing, you need to know that heat is a thing. As you polish it will warm the plastic. If it gets too hot it can destroy the plastic. I really didn't find this to be a big problem. Just keep the polisher moving, don't stay in one area long, and stop occasionally to feel the plastic. If its warm take a break.
    7) I polished at medium-high speed. I do not know how to choose a speed, so I just picked what seemed to be polishing well and not getting too hot.
    8) Keep polishing until you are happy with the shine.

    At this point it should look great. If it does not, you either failed to thoroughly remove scratches from some grits (sand better) or you had trash at some step (clean better).

    Wet Sanding, Equipment Used:
    I found that machine anding using cheap sandpaper gave bad results here. I used foam-backed 3M Trizact pads for high grits. I also used a foam interface pad, because the auto paint store thought the hooks from my DA pad were adding scratches somehow.

    Remember to spray with water using a little dish soap to break surface tension. Don't buy a spray bottle, buy a cheap $1 bottle of some kind of cleaner and dump it out. The empty spray bottles are usually like $4.

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    3M Trizact pads are expensive. They did seem to get better results. I bought an assortment from eBay for about $35. They last a long time if you keep them clean.
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    Foam interface pad goes between the sander and your abrasive.
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    I used a cheap DA sander from Amazon. Are more expensive ones better somehow? I really don't know. It worked fine but leaks air at the threaded connection because its crappy plastic.
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    Hopefully this helps someone. It seems like an insanely over-complex process to me, but this is the only thing I tried that got good results. I think next time I would try hand-sanding even higher grits, sand to a lower grit but add a compound step before polish. If you have a better process please do post it! And I am very interested to know which of the things I am doing are wrong - please post.

    #2 1 year ago

    WOW... Thank You for sharing this.

    I've purchased a few repo's before (Bad Cats / TZ and Earthshaker, as I recall). However, I find they aren't as detailed or vibrant in color as the originals.

    I'm excited to give this method a try. Plus at $75-$100 for a repo this is a no-brainer.

    Thanks again
    Kerry

    #3 1 year ago
    Quoted from Kerry_Richard:

    WOW... Thank You for sharing this.
    I've purchased a few repo's before (Bad Cats / TZ and Earthshaker, as I recall). However, I find they aren't as detailed or vibrant in color as the originals.
    I'm excited to give this method a try. Plus at $75-$100 for a repo this is a no-brainer.
    Thanks again
    Kerry

    Thanks! I would love to see how yours come out and trade notes.

    Reply

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