I wonder how much current would be required to substitute a DC power supply for the battery.
A little googling indicates a guy driving screws into a knot drew 9a on an 18v cordless drill:
I don’t think most users put that much torque on the routers, but the RPMs are pretty high.
There are 18v 20a supplies on eBay. But then the other problem you run into, is you’re going to need an enormously thick cable to run even 1.5 meters between the power supply and the router to keep your loss to 1% or better.
Maybe the power supply could be mounted to the x-axis beam to keep the cable short?
What type of loss (do we need to keep it to 1% or better) would be acceptable?
Here is a cable calculator: