Guys
I needed to make a very thin groove on a differential drive coupling on my sons RC car. This needed replacing because it was broke. The groove was for retaining a circlip that was only about 3mm accros. After pondering what i could use decided to grind down a Stanley blade. Put it into my parting tool holder and it worked a treat. I even parted the piece off afterwards and it stayed sharp enough to finish off a couple more. It works fine at slow speeds on mild steel, aluminium and even worked on a piece of semi hardened steel.
Hope this is helpful
Paul