please need guidance on servo system n drive

[15mgtar]

I'm a total newbie when it comes to ac servo motor, can someone explain to me what is the difference between 1000 p/r and 2500 p/r encoder?
which one do I need? and also for the servo drive is it any different if I have 1000 p/r or 2500 p/r?

[Al_The_Man]

The p/r of the encoder decides your theoretical positioning resolution, before any mechanical inaccuracy is taken into account.
This you would have to calculate depending on any gear reduction between motor and final positioning.
In cases of high rpm operation, you would also have to be aware of the frequency capability of the positioning controller or drive.
A common range in general commercial use would be 1000 to 2500p/rev.
As a rule, the drive or controller can be scaled to cover most encoder resolutions.
Forgot to add, your resolution is x4 the basic p/rev of the encoder, so 2500 will be 10000p/rev on controllers that multiply the quadrature pulse this way.
Al.

[15mgtar]

hmmm it's kinda hard for me to understand this engineering stuff. btw if I get a 2500 p/rev servo motor and 2500 p/rev encoder to match it would I be able to run it under winxp pentium quad 2 core 3ghz? I think the parallel port can only goes realiable less than 100khz.

[Al_The_Man]

What system are you using if you are reading the encoder through the P.P.?
There is no '2500 p/rev' servo motor, it just applies to the encoder, unless you mean drive?
Al.

[15mgtar]

Originally Posted by Al_The_Man What system are you using if you are reading the encoder through the P.P.? There is no '2500 p/rev' servo motor, it just applies to the encoder, unless you mean drive? Al.

what is P.P? I plan just to use mach3 and parallel port for my servo and enconder just like stepper?
yes there is an ac servo motor with 2500 p/r. ms-motor sells them

[Al_The_Man]

Originally Posted by 15mgtar what is P.P? I plan just to use mach3 and parallel port for my servo and enconder just like stepper? yes there is an ac servo motor with 2500 p/r. ms-motor sells them

It sounds like you want to use the P.P. (Parallel Port) to read the encoder for positioning?
Mach won't do it.
The encoder goes to the drive to close the loop.
I think there is some mis-communication here?
Al.

[15mgtar]

So If I use mach3 what ac servo motor and encoder should I get? Should I use P.P or smoothstepper? and How big of a ac servo motor should I buy (1000w enough?) I'm really blind at this. Thank you for replying so far.

[mactec54]

15mgtar

Take a look at these videos of this machine has 400w ac servo motors, this will help to give you an Idea of what you need for your machine

YouTube- cncvids 028.AVI
YouTube- cncvids 020.AVI

[rodjava]

15mgtar.
I was a total newbie when it came to choosing servos or steppers so I can feel your pain.

I ending up with AC servos and drives from DMM technology. You don't have to worry about adding or matching encoders because they are already built in. The encoder counts are suppose to be off the hook compared to other encoders.

Check the specs is all I can say.

As I understand it, the codes from the encoder are read or go through the DMM drives and you don't have to worry about Mach3 encoding anything.

I think that my 400w servos would be enough for a machine 2-3x bigger than my 30x48" router. And my home made cnc router is made from mostly 1.00 thick aluminum. Great thing about these servos is that they are not humongous and would fit in a small machine just right.

I'm glad I didn't go the stepper route or the issues with DC servos and matching up encoders.

PM me if you want more info. Like it said, I know what you are going through. Been there, done that.

Rod

[15mgtar]

THANK YOU GUYS!!! I will consider atleast 660w ~ 1000W minimum just incase. I am sure that I will have more question as I go on designing later.
btw. very nice machine mactec very smooth!!! I can only dream making a machine that runs that smooth!!!.
I'm not an engineer but I LOVE machinary. especially CNC ones