Grinding Screw Channels Away Inside Enclosure

[Haberdasher]

I'm seeking opinions about the best way and the preferred tool for you guys when you need to get rid of some material inside an enclosure.  I've never really had to do this before so I'm hoping to work smart without banging up the box.

Situation:  I bought 2 1690ns's (1590C clones) with nice powder coat from PPP a looonnng time ago, and now I'm realizing they aren't the best choice because there isn't quite as much room at the inside bottom (well, really the top I guess) as a 1590bb tall.  This is mostly due, I think, to the rather large interior screw channels.

So what is the most efficient method/best tool for the job?  Any opinions out there?
FWIW, I've got a rotary tool with some accessories, a drill, and some other stuff like files.  My neighbor offered me the use of his 4 1/2" angle grinder but I don't think he realizes how small these enclosures are, lol.  I could see where one of those oscillating tools with a skinny blade on it could be pretty useful, but I don't have one.

[EBK]

Rotary tool with a high speed cutter bit.


Work very carefully and precisely.  These things eat anything in their path in an instant (they will cut as if your enclosure was made of butter, so don't think you need to apply any sort of pressure).