Aluminium FEA optimalized CNC router

[PotatoMill]

Thanks for the quick response Fenza and Remrendes

According to a quick estimate I did I dont think i'm going to need any more torque than what these closed loop steppers deliver; http://www.aliexpress.com/item/new-o...a-82b3fb4b4813

Estimates done with

-40kg weight of moving part
-130N force of cutter (excessive)
-20N friction
-85% efficiency
-10 m/s^2 acceleration (more than I think i'll need, but I haven built any CNC machines before so i'm not certain on this.)
-5mm lead

Using T = (F*l)/(2*PI*n) where F is total force, l is lead per revolution, n efficiency
I get 0.44N well within

However I do know that theory and experience dont always match up. And in real life there could be some factor that make the estimate wrong.

[Fenza]

Thanks for the quick response Fenza and Remrendes

According to a quick estimate I did I dont think i'm going to need any more torque than what these closed loop steppers deliver; http://www.aliexpress.com/item/new-o...a-82b3fb4b4813

Estimates done with

-40kg weight of moving part
-130N force of cutter (excessive)
-20N friction
-85% efficiency
-10 m/s^2 acceleration (more than I think i'll need, but I haven built any CNC machines before so i'm not certain on this.)
-5mm lead

Using T = (F*l)/(2*PI*n) where F is total force, l is lead per revolution, n efficiency
I get 0.44N well within

However I do know that theory and experience dont always match up. And in real life there could be some factor that make the estimate wrong.

Hi PotatoMill your math certainly is correct but it doesn't account for the full picture. I use Kollmorgen MOTIONEERING to calculate more precisely what kind of motors are required, it's a little tricky to understand in the beginning but sticking with it pays off massively! http://www.kollmorgen.com/en-us/serv...eering-online/ here's the link to their site. I use their older application at the bottom of that page, it looks like they have a new online tool available now.

Kollmorgen have a huge range of motors available and the MOTIONEERING app helps point you to which is suited for your machine, I just use the data from that motor to base my search for a cheap servo / stepper system off of.

Also always remember that steppers holding torque is not the same as a servo rated/max torque.

A good rule of thumb that I use (though I'm not entirely sure it's correct) is that a 3Nm stepper is roughly equal in power to a 100W Servo.

Hope this helps!

Fenza

[PotatoMill]

Hi PotatoMill your math certainly is correct but it doesn't account for the full picture. I use Kollmorgen MOTIONEERING to calculate more precisely what kind of motors are required, it's a little tricky to understand in the beginning but sticking with it pays off massively! http://www.kollmorgen.com/en-us/serv...eering-online/ here's the link to their site. I use their older application at the bottom of that page, it looks like they have a new online tool available now.

Kollmorgen have a huge range of motors available and the MOTIONEERING app helps point you to which is suited for your machine, I just use the data from that motor to base my search for a cheap servo / stepper system off of.

Also always remember that steppers holding torque is not the same as a servo rated/max torque.

A good rule of thumb that I use (though I'm not entirely sure it's correct) is that a 3Nm stepper is roughly equal in power to a 100W Servo.

Hope this helps!

Fenza

Great tool, very helpful. I'm trying both the new and old now, the old one seems better actually.

[remrendes]

Estimates done with

-40kg weight of moving part
-130N force of cutter (excessive)
-20N friction
-85% efficiency
-10 m/s^2 acceleration (more than I think i'll need, but I haven built any CNC machines before so i'm not certain on this.)
-5mm lead

With 5mm lead is not the best ballscrew for you. You shoud use the motors up to 500rpm. Under this, you nearly can get a full holding torque.