I have 3 ballscrews for the 3 axes. (X-Y-Z)
Screw Dia.--- Screw Lead --- Long--- Starts
5/8 in ----------- 13/64 -------- 42in ------ 1
1 in --------- 1/4 --------- 48in ------ 1
12mm --------- 2mm ----------- 30mm ------- 1

I being reading Mach 3 user guide, it helps, but, Do I need to use some kind of reduction gearing "gear box or timing belts and pulleys belts".
Or I can connect direct to the steps motor to the screws
The step motors are 300 oz/in with 10us steps.

I'm just want to use for wood milling or router.
I will prefer to use in mm units.

When I calculated the mach3 steps per unit, using inches units one of the ballscrews gave me 25400 ( I think they are pulses). Soo.. Do I need to increases the frequenzy to 35000Hz?

I know if I use gear box I will increase the torque but lose speed.
How much torque do I need to milling wood in 3D?

I dont think you need a timing belt with 300oz motors. Unless you have one large machine, i would not bother. Getting a timing belt on there will increase resolution, and i believe torque. But like you said, how much torque do you need for milling wood in 3d?

finding a gearbox that has no backlash will be tough; not to say expensive too
Timing belts are easy to set-up and very stronge; i have never had a problem with mine on my Z axis for the lathe; runs just about every day

That is true, i notice many who put a timing belt on their Z axis of milling machines.
I have got two stepper motors sitting around with a pulley already attached to the shaft, i guess i will use a timing belt for when i convert my lathe

When I calculated the mach3 steps per unit, using inches units one of the ballscrews gave me 25400 ( I think they are pulses). Soo.. Do I need to increases the frequenzy to 35000Hz?


Only if that axis will move faster than 60 ipm.

What about the connection between the screw and step motor.
I should use belts or direct shaft coupling.
I found some belts from W.M: BERG (http://www.wmberg.com/index.htm)
and they have 0 backlash

Use these: http://www.ruland.com/flexes.html