Re: [CAD_CAM_EDM_DRO] Re: Converter or Inverter for 2hp Bridgeport mill

To: CAD_CAM_EDM_DRO@yahoogroups.com
From: "ibewgypsie" <ibewgypsie@...>
Date sent: Sun, 04 Jan 2004 06:50:28 -0000
Subject: [CAD_CAM_EDM_DRO] Re: Converter or
Inverter for 2hp Bridgeport mill
Send reply to: CAD_CAM_EDM_DRO@yahoogroups.com

Hi

am new to the group, so hope this is appropriate.
The Home Shop Machinist just completed a series on rebuilding the
Bridgeport.
I am building a rotary converter and wonder if anybody knows if
turning the rotary transformer at synchronous speed would help
even out the current available from each leg. I have a small motor
with a mechanical variable speed drive that I am attaching to the
old motor that is the heart of the machine. Also have capacitors
to help 'tune' the system.

Bob McKnight
[ Double-click this line for list subscription options ]

I used a toshiba single phase in, 3 phase out inverter. I used the
bridgeport relay to turn on with dry contacts, left the overload in
place (overkill since inverter monitors too). I gutted the cnc drives
and upgraded at that time too thou. Inverter works great.

My phase convertor made the head rattle, inverter is much smoother.
Money well spent. I have my machine on a 30 amp 220 single phase
circuit now. Like I said I upgraded the cnc drives too. The 3 phase
cnc drive transformer had to go.

David Cofer




--- 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.

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