This is a Toolcraft JLS-03:
See that screw near the end of the barrel where the tip goes in? That means you have a very simple soldering iron with tips much different from what everyone is discussing. In particular, telling you not to file or scrub the tip.
They tell you not to do that for a good reason:
Filing or scrubbing a good tip will destroy it.
The thing is, you don't have good tips. They don't make good tips for this type of soldereing iron.
Good tips are made out of special alloys. They are very sensitive to mechanical force and scratching, and are made to be held in your soldering iron in a way that doesn't damage them.
Your soldering iron tips, on the other hand, are solid pieces of copper with a thin plating of iron.
You can file and scrub and sand your soldering iron tips because they are such low quality.
I own a (cheap) soldering station that uses tips like yours. They don't make fine point tips for it, but I pretty much use only fine tips. No problem. Hammer the cheap, solid copper tips to a point then file and sand them smooth. Tin the tip, and keep it properly tinned at all times afterwards.
You have cheap tips. The plating won't stay, it wears out quickly. It oxidizes quickly as well, and basically burns off.
- File or sand the filth off of it.
- Sand it smooth with fine sandpaper.
- Tin it and keep it tinned.
- Always apply solder to the point before you set it down while working.
- Turn it off when not in use.
- If it gets filthy and burned looking again, clean it off again.
- Never ever file or sand a good soldering iron tip.
I used to make my own soldering iron tips for that kind of iron out of a roll of really thick copper wire I had. No plating, just bare copper.
The iron I had at the time required screw threads on the tip.
I used to cut a section of wire, hammer and file a point on it in whatever shape I needed, then use a tap and die set to thread it.
This is the soldering iron I use:
The tip is just solid copper. If you look closely, you can see that it has been hand shaped: The point isn't symmetrical at all.
I use that iron to solder everything. I assembled a couple of boards with 0102 sized capacitors with that iron (and that tip) a couple of weeks ago. That is, I soldered 0102 sized SMD parts with that thing - by hand, no microscope.
Good tools are a good thing to have. I can't justify (to myself) the price of a good soldering iron like I used to use professionally just to build things occasionally at home. A bad tool properly used can still get the job done.