Re: [CAD_CAM_EDM_DRO] Need advice on upgrading 2 existing CNCs

braidmeister wrote:

>At the moment I am running Vexta 2-phase motors putting out about
>305in/lbs ea. I believe that they are either NEMA 32 or 34 size. I
>have one machine that is a CNC router and the other is a CNC plasma
>cutter. I am currently controlling them through a proprietary
>control box which also runs proprietary software (I won't mention
>who's just yet)
>
>Currently I am only able to reliably run 150-180 IPM before I start
>losing steps. I would like to run the machine at 400-600 IPM and jog
>around 800-1200 IPM. I can upgrade one of the machines for a cost of
>about $7000 that will get me within these specs through the CNC
>manufacturer...Is it possible to get this performance at a lower
>cost???
>
>My 1st thought is to look into servos, but I have concerns with
>there being interference with the Hypertherm plasma cutter machine.
>I am also at a loss how to properly select a servo that will be
>closest in mounting, torque and target speed. The other option is a
>hybrid type stepper like Oriental's AlphaStep or Animatic's
>SmartMotor with feedback like a servo.
>
>

I think you are dreaming to get 1200 IPM with steppers.

>Can someone tell me if a servo will reliably run on a plasma machine?
>
>

Yes, but it may not be simple. Some people have successfully run Gecko
servo drives on plasma machines, but they had to do some things to get
rid of interference. Probably the best bet is to put differential encoders
at the motors and differential to single-ended converters right at the Gecko
or other servo drive.

>What would you suggest, a hybrid stepper with feedback or servo for
>both machines?
>
>What kind of ballpark $ am I looking at to upgrade the hardware on
>one machine? (Steppers~Servos/power supply/Geckos etc)
>
>Where would you recommend that I purchase my motors to get the best
>deal?
>
>

If you really want 1200 IPM, you will need to select the servo motors
quite carefully. I hope you are not using leadscrews for motion at this
rate. You need either massively stiff leadscrews, or need to make the nut
rotate while the screw dosn't turn. Otherwise the "whip" will destroy the
screws.

Jon