Re: driving large DC motor questions

Hello,
I've got a small Emco Turn 120 CNC lathe that I've been slowly
working on when I've got time. Being a very small lathe, it only had
a 3HP DC spindle motor. However, the motors' armature voltage is
400VDC for a maximum of 6000RPM.

My point is that I shopped around for DC drives. I found that DC
drives for larger HP and greater than 180VDC armature are VERY
expensive, around $2000+. I opted for a 3HP AC inverter duty motor
and VFD for around $600.

As you are presumably needing at least a 15HP motor, you will end
up spending some money either way. However, check these out;

http://web3.automationdirect.com/static/specs/drivemotorcombos.pdf

I've got the GS2 drive rather than the better "sensorless vector"
DuraPulse drive. The DuraPulse drive will accept encoder feedback on
the motor for the ultimate in accurate speed control. These drives
also feature 0-10V analog input so that it can be driven with your PC
based control using various digital to analog converter products.
The encoder should also be able to be used for threading and
inches/revolution feedrate programming.

As you can see for yourself in the .pdf link I sent you, you can
get a 15HP motor/drive with encoder for $1896 and a 20HP combo with
encoder for $2286. Motors without encoder are a few hundred
cheaper. These prices include a 25% discount that Automation Direct
is currently running. These prices are pretty damn good if you shop
around a bit.

I'm pretty sure the Rutex boards won't do the job for your spindle
motor, even if you could "group" them together.

Get the specs off your DC spindle motor and shop around on Ebay
etc... to see if you can find a nice DC drive compatible with your
motor on the cheap. Otherwise, use the existing one until it
breaks. Or just tear it all out, sell what you can and put in a nice
AC motor/VFD combo like listed above.

I would like to hear about the gearbox arragement with the spindle
motor and spindle. Do you have gear ranges to change between?
Infinitely variable? What max RPM are you looking for etc...? What
are your plans with the toolchanger/toolturret? Good luck.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "vinnygenovese"
<superman@r...> wrote:

>
>
>
> I have just finished converting the X and Z Axis motors on my 1979
> Ikegai FX-25N turning center. I was startled by how much simpler the
> modern RUTEX 90H driver cards are compaired to the original Fanuc 5T
> electronics. My application requires me to be operating at the drop

of

> a hat , and what I like about the rutex / PC system I have built is
> that for a few hundred dollars more I can have a backup 90H card

ready

> to swap out in seconds.
>
>
>
> I also purchased a Rutex R991H (0-10 V output) to drive the Spindle
> motor. the R90H drive cards do not seem to have enough output to

drive

> such a large motor. I also want to have 'electronic gearing'
> capability.
>
> Using the R991H requires me to leave the old Fanuc Vari-speed servo
> drive in place , and that is something I would rather not do, As I

want

> all the components in the machine to be easily replacable.
>
>
> my questions are
>
> (1) is there a inexensive (0-10 Volt input ) , 15/20 HP dc drive

that

> I could use to 'upgrade' the 25 year old Fanuc 5T vari-speed drive.
>
> (2) If I hook up a 90H card to the spindle motor will the card

blow ?

> is there a way to gang together several RUTEX 90H cards to drive a
> larger motor ? or is there a simple amplifier for the 90H DC

output ?

>
> (3) also what is the used vari-speed drive worth ? would it pay to
> sell the drive and perhaps the dc motor and buy a VFD/AC motor

combo.

> (I only have about $1000 left now that the wife does not know about)
>
> Thank you anyone who responds.