I would like to file down (just a bit) a metal tube's end to make it completely flat. See a drawing of it in another question of mine on this site Fix a faucet that has a groove . Taking that drawing as the case, I would like to file it from what in the drawing is the top, in order for that top to be flat instead of having that groove. In reality the groove is very small, but it's big enough to cause a bit of a drip to pass through it despite a rubber part closing it from the top.
I was thinking that if there is some revolving small flat file for a drill, something like the following drawing (the flat black part being reminiscent of sandpaper):
I could point the drill towards the tube and file the edge so that there will be no groove and the rubber part will close it hermetically. I can't get to the tube's edge from the side because it's surrounded by another tube which goes farther than its edge. But I can get to it from the top.
I remember seeing something like what I'm looking for but much bigger (and perhaps for wood) and I can't find any images of it now. I'm probably using the wrong keywords.
So does such a file exist, and if so, what is it called?
Perhaps the rubber part that closes on the pipe is called a compression faucet valve cartridge.
I can't cut it off from the side. Unfortunately there is absolutely no access from the side.
As mentioned in a comment, the term seems to be a sanding disc. But at least so far, I can't find any narrow ones with a diameter of under an inch.
Do those exist? I just remembered where I've seen them - at the dentist. Though I assume dentists' tools would be super expensive. I just need an attachment for a drill.
Here's the best I could do (a cross section of what I have):
The dotted yellow line is what I need to file. Its diameter is a little under half an inch (around 1 cm). The green is the rubber part that's supposed to seal it.