Re: Converter or Inverter for 2hp Bridgeport mill

If you don't use the variable speed pulley, you are going to loose
spindle power at low RPM. The pulley provides about a 9:1 ratio
between slowest/fastest settings. The motor is 4 pole 1800RPM so you
could probably drive it safely to 3600RPM or a bit more. This only
gives you a 2:1 ratio in the constant HP area of the curve. This
means the lower RPM will have to come at lower than 1800RPM which
will be in the constant torque area of the curve with diminishing HP.

~petev

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Lee Studley"
<indigo_red@q...> wrote:

> In parallel to John's question, I'd like to know about setting the
> spindle/motor ratio on my varispeed BP also, so that I can control
> the speed via the VFD. Does anyone have experience doing this? Any
> caveats?
> -Lee
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Lee Studley"
> <indigo_red@q...> wrote:
> > VFD's are great!!
> > I think most VFD's have reversing builtin(?). Having a switch
> break
> > connections from the VFD to the motor doens't sound good to me. If
> > you want to keep the mechanics of the original Fwd/Rev switch, I
> > would suggest wiring it as a switch to control the VFD's external
> > fwd/rev option if it can be done as an external control.
> >
> > -Lee JMO-ICBW:-)
> >
> >
> >
> >
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "john_glynn57"
> > <john_glynn57@y...> wrote:
> > > I have just taken delivery of my own Bridgeport mill and want

to

> > > know which is the best option for powering the machine : an
> > inverter
> > > or a converter.
> > > My research to date suggests that a Hitachi L100 inverter is

the

> > way
> > > to go however I want to question this as follows:
> > > 1. I can run a dedicated 20A or 30A supply to the machine which
> > > should be able to handle the startup current demand of a
> converter.
> > > 2. If I use a converter I can use all the original Bridgeport
> > > systems without mosification ie Bridgeport speed

control,forward

> > and
> > > reverse,3phase coolant pump and shaping unit which is attached
> to
> > > the machine.
> > >
> > > My plan is to circumvent the original Bridgeport wiring and
> drive
> > > the Main motor(s) directly from the hitachi unit and setting

the

> > > motor speed at the low speed of 1400 and not using the valiable
> > > speed control of the machine at all. The hitachi will give me
> > speed
> > > control by varying the frequency however I do intend to use the
> > > original forward reverse switch. In addition I plan to replace
> the
> > > coolant motor with a single phase model.
> > >
> > > Am I doing the right thing.