Re: Reality Check for CNC mill

If you are spending that kind of money, I would definately go with
Gecko's (201's or 320's), and I would strongly suggest servo's too,
altho, steppers will work.

The price difference is probably not great between a large stepper
system and a servo system.

Eric

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "amoss70" <a-jmoss@a...>
wrote:

> I DID :) email russ and he said it looked ok, just to use 2 power
> resistors is series to keep the watts down.
>
> but there has been some offline chat about going with gecko's and
> servos instead, the camtronics 610oz motors direct drive, and ball
> screws was the suggestion.
>
> And dump the enco/rong fu and go with the square column enco, for
> about an extra $300 you'll never loose your x-y position when you
> have to raise the head for a different cutter length.
>
> when you're looking at a total price of $4000 for cad and

everything

> an extra $300 is nothing.
>
> Thanks
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "cnchomeman"
> <cnchomeman@y...> wrote:
> > The FET4 isn't a bad board but I am not sure it can hack the
> stepper
> > motors you are talking about. Maybe the FETS can take the

current

> > but what about the rest of the circuit board? The traces on

there

> > are not that large.
> >
> > Also my calcs show you need 80 watt (min) resistors on both size
> > motors.
> >
> > Download my current limiting resistor calculator software at
> > http://www.e-zflight.com/files/stepcalc102.zip
> >
> > It's for calculating resistors for unipolar motors.
> >
> > I am afraid you will need to go with gecko's (which isn't a bad
> > thing) to handle that kind of current. You COULD email Russ at
> > stepperworld and see what he thinks.
> >
> > Eric
> >
> >
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "amoss70" <a-jmoss@a...>
> > wrote:
> > > I'm looking to build a CNC mill and am currently in the design
> > phase
> > > and would like a reality check on my design. Any assistance or
> > > opinions on my design choices you can provide would be great.
> > >
> > > I did use MicroKinetics CNC Express as a sort of base idea.
> > >
> > > Thanks
> > >
> > > Base machine:
> > > Enco or Rong Fu bench top mill converted to ball screw on the
> > > X and Y axis.
> > >
> > > Stepper package:
> > > Stepper World FET-4 with the MOSFET upgrade. Uni-Polar Drive.
> > >
> > > Stepper Motors:
> > > X & Y axis NEMA 34's 344-610-DU 610oz 3.9v motors

connected

> > via
> > > toothed belt at a 2:1 ratio.
> > > Z axis NEMA 23 233-180-SU 180oz 2.7v motor connected via
> > toothed
> > > belt to the fine down-feed at a 2:1 ratio.
> > > 6 in Rotary table NEMA 34 344-304-SU 304oz 2.5v motors
> > connected
> > > via toothed belt at a 2:1 ratio.
> > >
> > > Power Supply:
> > > 24v 60A unregulated. It's actually an old UPS and by
> > > connecting across the positive and negative terminals I figure

I

> > > could get at least 60 amps plus a beautiful 3400-mAH reserve.

I

> of
> > > course clamp it with zeners for surge protection.
> > >
> > > Current Limiting: (this is where I'm the weakest)
> > > X & Y axis NEMA 34's 344-610-DU 610oz 3.9v motors will
> > > be connected in series with 5 ohm 50 watt power resisters.

(Not

> > wire
> > > wound)
> > > Motor: .97 ohm
> > > Power Resistor: 5 ohm
> > > Circuit total: 5.97 ohm
> > > Voltage 24v/ 5.97 ohm = 4.02 amps
> > >
> > > Z-axis NEMA 23 233-180-SU 180oz 2.7v motors will be
> connected
> > in
> > > series with 5 ohm and a 2 ohm 50 watt power resisters. (Not

wire

> > > wound)
> > > Motor: .9 ohm
> > > Power Resistors: 7 ohm
> > > Circuit total: 7.9 ohm
> > > Voltage 24v/ 7.9 ohm = 3.03 amps
> > >
> > > Rotary table NEMA 34 344-304-SU 304oz 2.5v motors will be
> > > connected in series with 5 ohm 50 watt power resisters. (Not
> wire
> > > wound)
> > > Motor: .62 ohm
> > > Power Resistors: 5 ohm
> > > Circuit total: 5.62 ohm
> > > Voltage 24v/ 5.62 ohm = 4.27 amps
> > >
> > >
> > > CNC controller:
> > > Pentium 400+ something running Win 2000 or Win XP
> > > CNC controller software:
> > > MACH 1 and upgrade to MACH 2 when available.
> > > CAD/CAM:
> > > BobCad v18 upgraded to v19 when available.