What kind of dc servo should i buy ?

[etet100]

Hello

I'm building amateur router. Some photos :

http://www.cnc.info.pl/album_pic.htm?pic_id=3987
http://www.cnc.info.pl/album_pic.htm?pic_id=3957

I'm going to replace steppers (1Nm) with servo motors. Driver that i'm going to use is modified elm chan servo controller so i need dc motors.

I will buy servo here

http://www.akcesoria-cnc.pl

but i have no idea what's the difference between servomotors

http://www.akcesoria-cnc.pl/?menu=grupa&kat1=6

and dc motors with encoders

http://www.akcesoria-cnc.pl/?menu=grupa&kat1=5

Should I use single channel encoder or dual channel ? Which one has quadrature (incremental) encoder ? How should i know ?

Is it possible to use direct connection between motor and screw ? In this case servo motor will work at low speed (max 2000 rpm).

How big servo should i use ? I need at least the same power as i've got now. 40W, 50W ,70W ? 100W ?

Does it make sense ? What will be better : bigger steppers (2Nm) and better drivers (TB6560 instead of old L297 and L298) or servo motors. Now i have problems with loosing steps.

A.R.

[Al_The_Man]

Originally Posted by etet100 Should I use single channel encoder or dual channel ? Which one has quadrature (incremental) encoder ? How should i know ? A.R.

I think you mean single ended or differential? Both are quadrature encoders.
Single ended have 1 output/channel and differential 2 per.
Differential uses RS422 line drivers and receivers for noise immunity, if your drives take this type, this is preferred, if the drives are single ended in, you can use either type encoder but do not get the noise immunity afforded by differential.
Regards the motors it depends on whether is was due to poor torque performance curves on your stepper/drive combination or whether they were under rated.
DC servo's tend to have max torque at zero rpm and remain fairly flat or dropping very slightly up to the max rated rpm. You would need to look at the torque curve spec on the motor.
Al.