Quote Originally Posted by Mattia View Post
The ballnut housing has a 40mm diameter hole, which suggests a 25mm leadscrew to me. That would line everything up with the machined holes in the endplates. Overkill, perhaps, but what would the major downside be other than the need for a lot more power?
The only slight draw back is lower acceleration, a thinner lighter screw will accelerate quicker with less power required. Depending on what motors you fit this will be hardly noticeable for the most part unless you are doing lots of point to point moves or short moves like in 3D jobs.

Bigger isn't always better or can be called over kill, because all it's doing is crippling the performance and costing extra. It adds nothing to the machine but weight and money.!

If it was me I'd be fitting 2020.!

I'd also be looking to stiffen up the gantry. Although the Aluminium cross plate may look strong because it's a thick piece of aluminium it's actually not because it's just a flat and unbraced so at that width it will vibrate when cutting, this vibration will transfer into the spindle so will show in the cut quality.
Also don't be fooled into thinking the rails will stiffen it up because they won't and don't. What it needs is a perpendicular brace across the back to make it like "T" on it's side.!