Many Thanks for Phil , Mike and Joat for the useful informations.
Thanks a lot about diameters of routers, and,no i' m not really much limited by the diameter. Just a part to change.
(Did even thought of disassembling a plunge router from it's base to use it, but using round ones is more straight-forward.)
To Joat , about air motors:
I use air motors already,It's neat and light but it really uses a lot of air.
More than I can possibly produce to get a 2 or 3 HP output.
My compressor is a 3 HP 100L and quite big enough for me.
The overall loses are too big.
One big advantage of air is motors are light-weighted,Second it cannot deliver electrical shock in wet places , but compressors are monsters.
Good for the big factory production-line. Truly some interesting things in the US market .
(Makes me sometime think that I live in some kind of third or 2nd world here in France.)
Milwaukee : Milwaukee | 3-1/2 Max HP Fixed-Base Production Router with Electronic Variable | Home Depot Canada
Looks great .But no metric collets. And made in china.
(With love and care).
Dewald DW618 could do, probably compatible with many collets.
Has been made in 230v but discontinued.(Don't know where it comes.) DEWALT DW618 2-1/4 HP Electronic Variable-Speed Fixed-Base Router - Amazon.com
There are inconveniences like shipping, taxes, and this annoying 110v.
110v adds approx 5 Kg - 10 Lbs to it, with a pricey 3KW transformer.
For the moment,needing a motor, I did order a Felisatti, thats European made .
All collets sizes, metric and imperial, and 230v.
Then, I'll test workability with it.
Many thanks, waiting to get this Felisatti next week.
I' ll tell how it work.