Rounding Corners on Aluminium Plate

[Jigantor]

I don't suggest anyone try this because it could be dangerous.
I have tried all sorts of ways to round the corners on the plates I use.
Band saw, linishing and a press with a die but it never gets a perfect round corner and it always needs linishing. Today I decided to try using a router.
I have a router table and purchased a cheap router bit to use.
Clamped the 6mm or 1/4" thick plate between some pine studs to cut down the chatter.
Here is the result.
I then tried rounding the corners of a 100mm or 4" diameter tube that had been 1/3rded.
Here is the result of that test.

Ji