Aluminium FEA optimalized CNC router

[remrendes]

Requirements
Speed: standard 0-2000mm/min max 3000mm/min
RPM needed:
5mm lead; standard 0-400RPM, max 600RPM
10mm lead; standard 0-200RPM, max 300RPM

A stepper motor seems to lose it torque from 300-500RPM
A standard servo motor has full torque up to 3000RPM. However to utilize the whole range I would need a 10:1 or a 5:1 reduction.

If you buy a not Chinese stepper, probably it is higher, like the price :) But yes, you should calculate up to 500rpm.
With 5mm lead from 2:1 to 3:1 usually enough with servos. On 2.5:1 ratio I can get up 6000mm/s no-load speed on 3000rpm. But some motors could do 4000rpm.

[Fenza]

You could always use more powerful Stepper motors to negate the loss of torque at higher rpm. Also you could simply run your machine with higher rapids using servos so less of a gear reduction is required. 10mm pitch 10m/min rapids and a 3:1 reduction doesn't sound too bad! Ball screws have a maximum rotation speed so make sure you're not going to be over rotating them. 1,000 rpm is a pretty conservative speed but just be careful when it comes to spinning long ball screws at higher rpm.

If you'll be happy running at 3m/min then Open Loop Steppers will be a good choice. Rpm and microstepping both change the available torque so it'll be best to work out what torque will be required and choose the motor based on your calculations.

Cheers,

Fenza

[PotatoMill]

You could always use more powerful Stepper motors to negate the loss of torque at higher rpm. Also you could simply run your machine with higher rapids using servos so less of a gear reduction is required. 10mm pitch 10m/min rapids and a 3:1 reduction doesn't sound too bad! Ball screws have a maximum rotation speed so make sure you're not going to be over rotating them. 1,000 rpm is a pretty conservative speed but just be careful when it comes to spinning long ball screws at higher rpm.

If you'll be happy running at 3m/min then Open Loop Steppers will be a good choice. Rpm and microstepping both change the available torque so it'll be best to work out what torque will be required and choose the motor based on your calculations.

Cheers,

Fenza

Why not closed loop?

[Fenza]

Why not closed loop?

Personally I'm not a fan of closed loop steppers... Open loop steppers are cheap and Servos are great performers, closed loop steppers are neither...

I think it is possible for you to achieve your desired level of performance using the cheaper open loop steppers. 3Nm stepper should probably be around about right directly coupled to a 5mm ball screw.

Servos you'd be looking at 100-200W I believe.

Hope this helps!

Fenza

[remrendes]

Personally I'm not a fan of closed loop steppers... Open loop steppers are cheap and Servos are great performers, closed loop steppers are neither...
Fenza

A bigger steppers is a good idea. You can get enough torque in a no-load operation. Just you will get higher inertia as well.

[PotatoMill]

I have heard open loop steppers is not good for point to point 3D toolpaths. They loose step easy and you cant push them very well.