How to fix your case when the mating surface is damaged

[Sandblaster]

How to fix your case when the mating surface is dinged or scratched.
I sold a case to a customer that had damage on the mating surface.
Somehow we missed that on inspection
This type of damage can easily be fixed.
First, you want to clean the mating surface so you can see what you have to work with.
As you can see, this case has a bunch of gasket material left over from disassembly.

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So, a quick trip to the wire wheel (I use a fine wire wheel as the coarse wheel can do damage) will remove the gasket material and expose what's underneath.
Some guys like to use a razor scraper to remove the gasket material but you need to be careful as you can scratch up the surface very easily.
Regardless of the method you use, the mating surface should be very clean when you are done.

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Once done, it reveals that we have two problems.
We have a scratch on the left side and the case was sticking out a bit on the right side.
So, I fixed the right side using a fine file.
All you need to do is keep the file flat while gently moving it back and forth until the protruded surface is smooth with the rest of the mating surface.
You can feel it grabbing on the protrusion.
As soon as the protrusion is gone you will feel the file run smoothly over the entire surface.
Remember, you don't want to press very hard and you don't want to remove any of the mating surface causing dips or valleys.

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When you are done the mating surface should look something like this:

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Once that is done I take a very flat surface with some 500 grit sandpaper and run it gently over the affected area.
Normally I use my metal sanding block but I couldn't find it so I used a small framing square

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It only takes a few seconds to get a surface that looks like this:

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Now that it is all cleaned up you can really see that scratch.

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Next, you will need to JB-Weld, a razor, and something to mix the JB-Weld on and with.
Something like this.

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The mixing surface should be really clean.
If I had the option I would use a flat metallic, glass, or plastic surface.

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Squeeze out equal parts of the JB-Weld and mix thoroughly.

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Once it is thoroughly mixed apply a dab to the scratch.

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Next, take your razor and while holding it at 90 degrees to the direction of the scratch slowly pull the razor toward you while holding it flat to the mating surface.

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After scraping with the razor blade you should have something that looks like this.

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Before you go any further, let the JB-Weld dry thoroughly...

Depending on the room and material temperatures the JB-Weld should be dry enough to work with in about 2 hours.
You can probably do it sooner but why push it?
You can test how hard it is by the mixing board you used as it should have a little left on it.
Then, take your 500 Grit sandpaper and give it a few strokes.
When your done, run your fingernail across it.
If you can feel any indentation or high spots you either need to sand a little more or fill it again.

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Once it is smooth you are done.
Of course if you want to get really crazy you can lap the cases but that will be covered in another article

[Motorrad]

should I comment on all the damage you did by using a wire wheel?

[Sandblaster]

Absolutely.
I guess I should have specified which wheel I use.
I know if you use a coarse wire wheel it will damage the aluminum but I have found that the fine wire wheel has always worked good for me.
What has been your experience with a fine wire?