Re: Converter or Inverter for 2hp Bridgeport mill

Thanks Vavaroutsos and Lee,
My Understanding, at the moment, is this and I should proceed as
follows:
1. The inverter route is the way to go.
2. I should setup the inverter to control the forward reverse
control.
3. I should setup the inverter and the Bridgeport to run at the low
speed of 1400 RPM and the inverter to deliver 1400 RPM at 50Hz.
4. I sholud increase the motor speed by increasing the frequency of
the inverter to >50 to simulate the higher speed of the Bridgeport
and use the pulleys to actually gain the desired spindle speed at
the toolcutter end.
5. By Carrying out 3&4 I should maintain the normal speed\torque
curce for the Motor.

Please tell me if I am wrong.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "vavaroutsos" <pete@v...>
wrote:

> 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.