Re: 9x42 conversion

Not asking a really hard question. I am looking to learn
what has worked for other people and what has not. I do
not want to make the same mistakes others may have made.
I guess the only one who has made a sucessful Bridgeport
conversion here is Ron. And he did it using servo's.
I am sure it is superior to steppers, with an added cost
of course. I will consider it if I can get a setup for the
right price.

Thanks,
Scott

> You are not asking a easy question...Not enough info is

given...For

> instance are you going to use the acme screws, or get
> ballscrews...What cutting speeds and rapids do you want...
>
> Also, 1000 oz-in is only one number, probally holding torque...You
> need the torque and rpm curve to know how much power you have for

the

> speed you want...Typically for steppers size nema 42 the torque

drops

> off sharply at 300 to 500 rpm or so...The curve is dependent on

the

> motor and the drive...usally a mfg publishes several curves for

same

> motor at different voltages to show how different drives will
> perform...
>
>
> Wally
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Polaraligned"
> <polaraligned@o...> wrote:
> >
> >
> > Thanks Wally. What I am looking for is the torque rating that is
> > sufficient to drive a full size Bridgeport mill. Is 1000 oz-

inch

> > enough? should I go to a larger 1300 oz-inch?
> > As for the driver, I heard that the Gecko's barely had enough
> > current ability to handle driving motors on a large mill, plus
> > they are not overcurrent protected. I just want to know what
> > people out there are using sucessfully for Bridgeports. It is
> > a much larger and capable machine than a import Mill/Drill.
> > I will be using Mach 2 software.
> >
> > Thank You,
> > Scott
> >
> >
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "cnc_4_me" <cnc4me@g...>
> > wrote:
> > >
> > > Bridgport used nema 42 motors, and most people use this
> size...But
> > > some have successfuly used nema 34...It depends what you have
> > access
> > > to or have laying around, or how much you want to spend...and
> what
> > > kind of performance you want...
> > >
> > > Most people use a gecko stepper driver.
> > >
> > > http://www.geckodrive.com/
> > >
> > > they are adjustable up to 7 amps...The current you should use

is

> > > dependent on you motor...
> > >
> > > There is a gecko support group here...
> > >
> > > http://finance.groups.yahoo.com/group/geckodrive/
> > >
> > > The following is a general description of steppers to get your
> > feet
> > > wet...A few things you should know is steppers for the same

frame

> > > size can have very differnt torque and speed curves...In

general

> a
> > > stepper with the lowest nameplate voltage and highest current
> will
> > > give you the best torque and speed...A 1.5v stepper is very

good

> > and
> > > a 5v stepper is so so...
> > >
> > > Also note that the stepper is not driven by it nameplate
> > > voltage...You typically run a stepper 20X its nameplate
> > voltage...So
> > > a 1.5v stepper is run at 30vdc...The gecko drives can be run

up

> to
> > 7
> > > amps and 80vdc...Gecko stepper drives need a external power
> supply
> > > you have to provide...
> > >
> > > I would suggest reading back in the archives in this group and
> > geckos
> > > at least 1 year to get a better handle on who, what were,

when,

> > and
> > > why...I just got done doing the same...Lots of good stuff

there,

> > even
> > > what software to use...
> > >
> > >
> > > Wally
> > >
> > >
> > >
> > > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Polaraligned"
> > > <polaraligned@o...> wrote:
> > > >
> > > >
> > > > Can anyone tell me what size steppers are the minimum

required

> > and
> > > > also when looking for a stepper driver, what maximum current
> > rating
> > > > is needed to drive these steppers? The steppers will be
> driving
> > > the
> > > > leadscrews with a 2:1 reduction via a belt drive.
> > > >
> > > > Thank you,
> > > > Scott