DIY Marble - Metal Machining 3 axis CNC Router

[pippin88]

Regarding two rails per side, or three on the Y axis:
Have you seen any commercial machines do this?
Just go with bigger rails if you need the load rating capacity.
A second rail adds a lot of cost and hassle machining and aligning. (Though it appears you have access to machines for doing this).

What are the cutting forces in marble machining? How do they compare to metals?

[Halbmond]

Regarding two rails per side, or three on the Y axis:
Have you seen any commercial machines do this?
Just go with bigger rails if you need the load rating capacity.
A second rail adds a lot of cost and hassle machining and aligning. (Though it appears you have access to machines for doing this).

What are the cutting forces in marble machining? How do they compare to metals?

For cutting marble you need higher speed spindle than required for metal and less kW.
Max spindle kW for marble in the market is 15-18 kW with minimum 12.000 rpm
Actually for marble machining 9-12 kW is just fine, 15 kW is required if you gonna use 800 mm diameter saw.
If you are going to have 5 axis, each axis must have min 500 Nm torque capacity.

Min spindle kW for metal machining in the market is 15-20 kW - 6.000 rpm


I have seen lots of commercial cnc machines having 2 linear rails on each side. Paralel or different directions.
We are going to buy a new gantry style machining center. I have seen lots of catalogs.

For marble 1 linear rail is enough, for steel it depends on your y axis length.

Actually I think 1 linear rail will do fine, because my y axis is not wide much.
Expanding the rail size is better option. At the moment X axis linear carriage model : RGW35HC (Width: 100 mm) I will replace it with RGW45CC (Width: 120 mm,same length)

In our workshop we have 2 8 meters Z axis capacity horizontal and vertical CNC. You can machine 100 tons of any piece.
I will need much smaller CNC.

This CNC is for my friend and will be started to welding a couple of weeks later.

[pippin88]

I read this on my phone and did not really get the scale / size of the machine you are building (very large!).

Thank you for the interesting pictures of those very large CNC machines.

[Halbmond]

This was another design of mine for 6 axis machining of marble.
Both Bridge and Z axis is symetric construction.

My friend showed me some catalogues for same purpose CNC machines, mostly italian.
I came up with this design and project will start whenever they change their workshop to a bigger workshop.


I will share project technical drawings when this construction finishes.
There will be total 2 CNC with this type. Only difference that the other one will have concrete block X axis just like the one at attached pict. X Axis is not mobile

Base Foundation of this machine will be separated from workshop foundation by 5 cm.
There will be pits for anchor bolts below x axis footings. Those pits will be filled with grouting epoxy.

[Halbmond]

After pippin recommendation I changed X axis design.
After changing double linear on each X axis to one linear rail, mass of bed frame and bridge are changed.
Double linear rail type : RGW35CC - 35 mm width rail - 100 mm width linear carriage block
One linear rail type : RGW45CC - 45 mm width rail - 100 mm width linear carriage block

6 linear carriage bearings canceled, 2 piece of 4m length linear rail canceled.
With the reduction of steel profiles, there is approximately total 1.500 - 2.000 USD cost reduction due to one rail design.

Old Mass :

Bridge : 1.200 kg
Bed Frame : 4.800 kg

New Mass :

Bridge : 1.100 kg
Bed Frame : 3.950 kg

I need help about X axis drive. I think both X axis and Z axis should be rack&pinion design instead of ball screw.
At X axis ball screw is way above linear rail I didnt like it, and rack&inion will get the ram closer to the saddle for Z axis.
Any ideas.