Hi,

Just draughted up a design for a 4x4" router, (missing a few parts but the general design is there).
Rails will be HGW25, HGR20 on the Z axis, 2510 and 2010 ballscrews respectively. Rough gantry wiehgt will be 80-85kg.
Rails will be top/bottom mounted to minimise Z axis offset, with ballscrew at top.
I will use some 8mm plate and bolt or weld to the box section, then skim flat to provide a decent surface for linear guides.
Z axis will be supported by a couple of one way air cylinders coupled with a 5L reservoir.
Driven by NEMA 34 with 4.5Nm holding force, closed loop system and dual drive Y. UCCNC controller AXBB-E.

My main debate was whether to mount the gantry/X rails facing the same way like a lot of CNC routers (ballscrew in middle),
or like my current design (top and bottom). The current design significantly increases the rail spacing and rigidity however moves
the ballscrew to the top of the gantry. Being large linear bearings I was assuming that moments causing by the ballscrew acting on them from its
current position wouldn't be significant. I like the idea of having the Z axis close to the gantry for rigidity, especially as I want to
go through a fair bit of
aluminium and hard wood.

any thoughts/ideas/improvements welcomed.

Cheers