Rigidity.
Rigidity.
Rigidity.
Because they just don't work very well.Why don't we see machines like this?
1) V rollers imo are average at best for a wood router. They are no where near stiff enough for a metal cutting machine.
2) Mills can cut 5-10 times deeper per pass than what is being done in that video. A router is very inefficient at cutting steel.
3) Mills will give a vastly superior finish.
4) Mills will be much more accurate, due to their high rigidity.
5) Tool life will be much shorter on a less rigid machine, due to vibrations.