DIY Marble - Metal Machining 3 axis CNC Router

[Halbmond]

Greetings gentleman,

Here I would like to post my new welded construction 3 axis cnc router design.
X axis : 3.000 mm
Y axis : 2.200 mm
Z axis : 600 mm

It is now on design stage.
Material to be machined will be marble and carbon steels.
First post will be about Bridge - Saddle - Ram Design.

Center of gravity for total bridge assembly along with saddle and ram, is behind the Y axis Saddle which is pretty nice.

At first i started with one linear rail on each side of bridge (X axis) and one ball screw.(1st design)
Afterwards I increased the linear rails on each side to 2 in second and thirth designs.
Difference is,linear carriage mounted bridge supports on each side is 300 mm for second 200 mm for thirth and 140 mm for first.
Center distances of linear carriages is 200 mm for both second and thirth design.

Total 3 designs. I would like to hear what is your choosing among these 3.

Linear rails are roller bearing type for higher load capacity.

X axis
Linear guide rail Size : 35 mm
Quantity on right side : 2
Quantitiy on left side : 2
Ball screw size : 40x8 mm

For Y axis 3 linear guides . One of the linear guide rail is located on top with a different direction.
This will improve the strength of the bridge %20 higher according to the studies.
Linear guid rail size : 35 mm.
Ball screw size : 32x5 mm

For Z axis; there are 4 linear guide rails. 2 at rear 2 at sides.
Linear guide rail size : 28 mm
Ball Screw Size : 32x4 mm (may be this size will get smaller)
There is also possibility to change Z axis drive from ball screw to rack - pinion.
Rack and pinion will have less space therefore ram mass center will get closer to bridge.

There will be 2 counter weight pneumatic or hydraulic cylinders located on Z axis saddle for balancing the Z axis Ram.
This will improve Z axis servo performance.

Mass :

Ram : 240 kg Saddle : 240 kg Bridge : 1.200 kg

Y and Z axiss will have 1 kW servo motor - 3000 rpm drive, directly assembled to ball screw via coupling.
X axiss will have 2 piece of 1 kW servo motor directly assembled to ball screw.