Re: Servo's and Power supplies

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Jason Cox" <sinergy@o...>
wrote:

> Hello,
>
> I am currently working on a power supply to drive 3 servo motors

and have a couple of questions and would appreciate any help!

>
> The motors I have are 600oz/in from camtronics, and are rated at

38vdc 12amps max.

>
> 1. I am looking at a toroidal transformer and in my price range I

can reall only afford a 500va transformer. There are two I am looking
at, a 25vac 20amp or a 30vac 14amp.

>
> The 25vac will give me about 35vdc at 20a, and this is the one I am

leaning toward. My question is will there be any downside to running
my motors at 35vdc rather than 38volts or even higher? From what I
can tell I will only lose rpm and the toqrue is in the amps, is this
correct or am I way off?

>
> Im not even sure if 20a will be enough to power all three motors I

plan to do alot of 3d contouring. The machine I am retrofitting is an
RF-45 mill drill and I am driving the head rather than the quill, it
is fitted with 5/8" ballscrews x & y and 1" ballscrew in the column.
I am planning to connect x & y direct to the leadscrew and am
undecided with the z axis. I am hoping to counter balance the head.
Oh, and all leadscrews have .2in lead. Is the direct connection of
the motors a bad idea? Its just more simple and cheap for me at the
moment.

>
> 2. The second question I have is as to the protection of my power

supply, firstly the capacitor I am planning to use is a 47000uf 40v
not quite 20% higher voltage as geckodrive suggest, will this be a
problem? And secondly I hear of bad things happening during
deceleration of motors, how do I protect my power supply against this.

> I am running 3x gecko 320's.
>
> Thanks for any help, the list has been great reading and has helped

me get this far!

>
> Jason Cox.
>

You need fuses to protect the geckos durring deceleration
the motor act as little power generators that can destroy
you electronnics.
I had a few fuses blown before I was able to set the
deceleration parameters in the controller software just right.
I also have 600 oz/in motors and am thinking about trying a
direct leadscrew connection, not sure yet seams that there
is a industrial machine from RedCam http://www.redcam.com/
that offers a machine like that but they use 1000 oz/in motors.
Need to do some testing on this to see if the 600 oz/in can
cut the mustard this way.
You would be better of with more voltage and amps on the
Powersupply.
I have 4 motors rated 38v 5amp and my powersupply is 55v 15 amp.
Good Luck