New build.Stell frame cnc 1500X1000.Ball screw and gearing calculations

[ba99297]

Hi everybody
My name is Vagelis and I am from Greece
Sorry for my english. I use google translation in order to find some words, so be tolerant with me.

Last year I am trying to plan and build a cnc router for cutting wood,plastic and ali if possible. The machine dimensions ( of the rails ) are
X : 1000mm
H : 1500mm
Z : 300mm
As a key element of the frame is steel, with compounds mainly by screws
I have already bought the motors which are three Yaskawa 400 watt Sigma II with 3000rpm. The servos and a 2,2 Kw spindle ( without the inverter) are th eonly things that I have already bought..
Thumbnails of drawings I made in the spring are the following







These are not the final plans. I just upload them in order to give you a general idea of what i am going to build. The gantry will be about 60 kgr heavy

Do you think the motor are suitable for such a machine?
What cutting speed is possible to be achieved with these motors?
The servos and a 2,2 Kw spindle ( without the inverter) are the only things that I have already bought

In the original design I was planning to move the bridge with a single motor, and a ballscrew under the table in the center , which is why I ordered set of three motors and not four . Lately I'm a little skeptical that my choice and I think maybe I'm wrong . On the other even if I am wrong I cannot spent at least another 500 euros to buy extra motor and driver. Given this limitation of scenarios is

1. Nothing changes from the original design and move the bridge a ballscrew center

2. Buy extra ballscrew and placed on the Y axis two ballscrews ( right and left), and give motion by a motor with belt and pulleys

3. Move the axis Y with a ballscrew in the center and use the following technique
4. Use the rotative nut.. That means we keep the ballscrew stable and we rotate the nut
rotative nut - YouTube

second topic
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Now it is time to buy ball screws and linear motion equipments
The basic question that i have is what ball screw is better to buy
I mean of what diameter and mm per revolution

Also it is important to decide the gear ration between the motor and the ballscrew

The basic restriction is that i already have the motors (3 Yaskawa sigma 2 400 watt)
These motors are rated at 3000 rpm
At fist i was planning to connect them directly to the ball screws .

After reading this topic

Need Help! Ballscrew speed

i realize that the ballscrews have a maximum speed limit , depending on the diameter , length and mode stabilization at both ends. So based on the following calculator

Metric Critical Speed Calculator | Nook Industries
my own ballscrews (if i buy the 2005) could run

X axis length 1000mm maximum rpm 2478
Y-axis length 1500mm max rpm 1075
Z axis length 350mm max rpm 19739 ( this axis forget him )

That means with 1:1 gear between the motor and the ballscrew, the Y axis ballscrew would never run with 3000rpm because of the 1075 threshold.
I have many thing that i am thinking about but first i think it is better to hear your opinion
I repeat my questions

First question
Are the motors suitable for such a machine?

Second question
What cutting speed is possible to be achieved with these motors?

Third question
What gear ratio should i choose between the motor and the ball screw?

Forth question
What ballscrew should i choose?

Fifht question
Which of the following scenarios is the best choice for me

1. Nothing changes from the original design and move the bridge a ballscrew center

2. Buy extra ballscrew and placed on the Y axis two ballscrews ( right and left), and give motion by a motor with belt and pulleys

3. Move the axis Y with a ballscrew in the center and use the technique with stell ropes and pulleys
4. Use the rotative nut.. That means we keep the ballscrew stable and we rotate the nut
rotative nut - YouTube

I remind that the dimensions are 1000X1500X350, gantry weight 60 kgr, steel frame

Have in mind that i want to get as much as possible from my motors. I would aprecciate if you analyze your answers
Thank you for you time


Vagelis