Aluminium FEA optimalized CNC router

[PotatoMill]

Here is some info on corner speed. https://www.google.no/url?sa=t&sourc...JAddXnAgnBfq5A it's more apparent on these speed torque curves http://www.sanyodenki.eu/IMG/pdf/Ste..._06.12.N_e.pdf

[remrendes]

Here is some info on corner speed. https://www.google.no/url?sa=t&sourc...JAddXnAgnBfq5A it's more apparent on these speed torque curves http://www.sanyodenki.eu/IMG/pdf/Ste..._06.12.N_e.pdf

Yes, it is on the speed/torque curve, where the motor starts to loose his torque. Approx 4-600rpm on a cheap steppers.

[Fenza]

Hi PotatoMill, I see you specced 10m/s^2 acceleration. Now I'm not too experienced with routers and steppers (Mills and Servos is more my thing) but 1g is kind of a lot! I did a quick calculation and a 20mm ball screw 1,200mm length 5mm pitch with 40kg load will require over 3Nm of torque at the shaft to accelerate all the moving parts at 10m/s^2

Cutting forces are only small but the force required to overcome inertia and accelerate a 40kg load is great!

I believe 2.5m/s^2 would be a good target to try and aim for, though It would be nice if someone experienced with steppers and routers could chime in and advise. I believe 50in/s^2 is considered not too shabby in Mach3 which would be 1.27m/s^2

Hope this helps! That Kollmorgen app really is a great tool once you get used to it

Fenza

[PotatoMill]

I think it's more clear to me now.

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.

5mm lead will put me over the speed where the stepper starts to loose torque but it will also give me twice the force of a 10mm lead. I'm not sure i'm going to machine over 2000mm/min but for rapids I need a higher speed.

The weight of the X and Y cart is 30Kg. The Z cart is 20Kg
Cutting force; max 150N

After reading more on servos the torque advantages are clear. If my machine was bigger it would be obvious to use them, with the size om my machine there is not so much of a difference.

[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.