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Author Topic: how to fit servo mottors?  (Read 3438 times)

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Offline ziga

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how to fit servo mottors?
« on: September 03, 2007, 10:23:35 AM »
Hello

I have an old cnc mill machine. I wuld like to throw away my stepper moters and fit on it servo dc or ac motors i havent decidet jet.
I wuld like to put mach software on it.
I know thet servo motor needs 2 inputs, direction and frequency to tell it how fast it must turn. and an encoder givs to computer the information how much did it moved for real, and in wich direction it moved for real. When a machine have to make a sharp turn, it still have some moment and it still is moving in another direction, that culd be a problem couse it culd make a little mistake and if you doo a loot of sharp turns it culd end up as 1 big mistake(or so i think)
couse when i was using stepper motors it was jumping steps, so i figured that culd be the problem or that i wanted too mill  too hard metal.

My question is where can i read more on what output mach software gives i was looking over the manual and ther were detail info for stepper motors, but no detail info for servo motors, or does the step pin determin frequency and you just verify it with motor?
« Last Edit: September 03, 2007, 12:36:24 PM by ziga »

Offline jimpinder

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Re: how to fit servo mottors?
« Reply #1 on: September 03, 2007, 12:38:05 PM »
why not just put bigger stepper motors on it ????

Mach 3 puts out pulses for direction and steps on two wires. If treated correctly it is accurate. Your problem seems to be that you are trying to do something outside the capability of your machine, not Mach3.

If you put servo motors on, you MUST then wire up the encoder be cause Mach 3 will Not know where it is unless you do. I find steppers very, very much more simple.

Arc Euro Trade in UK has some very big stepper motors that will easily power you machine - so you should find some in your country that will do the job.
Not me driving the engine - I'm better looking.

Offline ziga

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Re: how to fit servo mottors?
« Reply #2 on: September 03, 2007, 12:52:47 PM »
jes it is true i culd put a bigger stepper mottors, but i wuld like to experiment how my machine wuld work under servo motors, since they generate biger torq, i culd than use the feadback to equipt bigger machine ( i happen to have an old shublin machin from i dont know wich year and it has a very old computer)
« Last Edit: September 03, 2007, 03:38:59 PM by ziga »
Re: how to fit servo mottors?
« Reply #3 on: September 03, 2007, 02:30:25 PM »
Any type of servo motors (brush or brushless) maybe controlled thro servo amp with Step/Direction inputs - see for example digital amp Elmo (www.elmomc.com). :)
Servo amp in position mode is like stepper with step defined by encoder resolution and velocity defined by frequency of input Steps.

Offline ziga

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Re: how to fit servo mottors?
« Reply #4 on: September 03, 2007, 03:43:53 PM »
so if i understand this corectly speed of servo motor is defined by frequency which you get from step pin?, but wat if you have to stop the motor how does the controler determin when the step pin goes low, it culd just mix it up with the frequency low impuls?

Offline comet

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Re: how to fit servo mottors?
« Reply #5 on: September 03, 2007, 04:03:33 PM »
ziga,
  you really need to sit down quietly and read the mach3 manual,to learn the basics
all the answers you need will be there,if you go for servo's, brushed DC are the cheapest.
using gecko 340/320 drives
tony

Offline ziga

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Re: how to fit servo mottors?
« Reply #6 on: September 04, 2007, 08:43:09 AM »
yes i was reading the manual again and i see i was slopy reading it ther is more info that i read, thy for the info i have to read it more in details.