DIY Build of Aluminium CNC Wood Router without Workshop & Tools

[JAZZCNC]

I had thought that the heavy version of the 45x45 would be strong enough as it is bolted along the back of it's whole length to 9.5 plate. I will look at replacing the top section with 45x90 then. Do you think this will be enough?

Nah even the heavy version isn't has strong as you think.!! The 45x90 will be better but I'd put it top & bottom and have the wide bit flat.
This way it ties into the sides better and gives more resistance to bending in lateral cutting directions.! It doesn't Add much to the vertical up & down strength plunging will inflict but the 10mm plate will help here and plunging should be avoided if at all possible anyway.! Most of the time the machines cutting and the forces are lateral.!!

10mm is just about ok for threading in Alu.

[WandrinAndy]

The 45x90 will be better but I'd put it top & bottom and have the wide bit flat.
This way it ties into the sides better and gives more resistance to bending in lateral cutting directions.! It doesn't Add much to the vertical up & down strength plunging will inflict but the 10mm plate will help here and plunging should be avoided if at all possible anyway.! Most of the time the machines cutting and the forces are lateral.!!

I would have thought that my design as pictured already provides lateral resistance roughly equivalent to what you're suggesting, as a cross-section of the bottom of the gantry consists of 45x45 bolted close to the backwards pointing 51mm leg of the 9.5 angle? And the 9.5 angle extrusion is bolted to both the base and the uprights of the X-carriage hopefully creating a very rigid joint?

[JAZZCNC]

I would have thought that my design as pictured already provides lateral resistance roughly equivalent to what you're suggesting, as a cross-section of the bottom of the gantry consists of 45x45 bolted close to the backwards pointing 51mm leg of the 9.5 angle? And the 9.5 angle extrusion is bolted to both the base and the uprights of the X-carriage hopefully creating a very rigid joint?

OK then go for it.!