Re: bridgeport - geckodrives and mach 2

Ted, I have a series 1 BOSS 6 with the original control and I think
the steppers run at about 85V. My machine will rapid at about 120ipm.

I wouldn't mess with the Hitachi VFD. Just get a 3HP unit that is
rated for single phase input. The Teco FM100 series is a good unit
for the money. It's available from www.dealerselectric.com. If you
have a series 2 machine with 4hp spindle motor, you can oversize the
VFD and run it on single phase input. De-rate it from 30-50% for
single phase input.

~petev

---- In CAD_CAM_EDM_DRO@yahoogroups.com, "ted_griebling"
<erichtg@h...> wrote:

> Hey guys, I'm right smack at the beginning of a similar conversion
> project. A bunch of friends helped move in a '79 Bridgeport CNC

this

> weekend. It came functional with a '98 AHHA CNC conversion using

all

> the original Textron (boss?) full-step stepper drivers.
>
> I've no 3phase, or 220v power even. Just 110v - 35A max (can't let
> two tools start up at the same time). To test the drives a friend
> and I hacked into the AC power box, bypassed the 3phase transformer
> and lit up the electronics and computer direct from 110.
>
> To power the stepper drivers we used a separate torrid to step 110V
> down to the specified ~55V and tied the three separate drive axis
> power inputs together. We had first tried to use the BP's built in
> 220V to 110V Electronics transformer with some success but stopped
> at the sight of smoke (transformer got a little hot).
>
> This has us wondering how many amps the stock drivers pull. Anyone?
>
> Performance was marginal in this configuration. I can't compare
> before/after performance as I didn't play with the machine much on

3

> phase. We started loosing steps when jogging the configured ~20ipm
> rapid -- especially when retracting Z and at extreme X table
> positions where the saddle supports a larger cantilevered load.
>
> Late last night I puzzled out the motor wiring and hooked the X

axis

> (wired in series) up to another NC control box I had built for an
> Enco conversion. It uses Centent 142 10x micro step drivers (an
> earlier generation of the Geckos). Using another PC and Mach2 I had
> the X axis jogging reliably at 80ipm. 90ipm appears to be the max.
> I'll probably back it off more for safety.
>
> The drives are powered at 40VDC and set to ~6.5A but I am unsure of
> the actual stepper current--it's somehow dependant on how the motor
> is wired. I understand Ohm's law but don't see how the driver knows
> to deliver ~3.5A max when the motor coils are wired in parallel vs.
> ~7A max for series (seems counter-intuitive).
>
> Les, or anyone else, do you know where to find the specs on the BP
> stepper motors? (Superior Electric version)
>
> Next is the spindle.
> I plan to buy a Hitachi L100-015NFU VFD from Drives Warehouse. The
> 015NFU model takes 220VAC single phase. I've a few (large) 1:2
> transformers and plan on stepping 110VAC up to 220VAC. But I

believe

> it is possible to bypass the drive's internal rectifier and just
> feed it 220VDC. My assumption is that I might get better

performance

> if I externally rectify and filter the 220VAC to DC as the internal
> DC filter cap is small and I suspect the cap is sized more
> appropriately for 3-phase.
>
> Anyone try anything like this?
>
> Wish me luck! - Ted Griebling
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Les Newell <les@l...> wrote:
> > Hi Aaron,
> >
> > I have converted my Series 1 BP to Geckos and Mach2. The machine
> > performs far better than with the original BOSS5 control. Rapids
> are
> > about twice as fast and movement is much smoother.
> >
> > Geckos are slightly undersized for the Bridgeport steppers but
> they work
> > quite well if the motors are wired using only two coils and the
> Geckos
> > are run at full current and about 75V.
> >
> > Les
> >
> > Aaron wrote:
> > > Has anyone converted a bridgeport mill using mach2 controlling
> geck drive
> > >
> > > .....any comment oon this combo would be grately recieved
> > >
> > >
> > >
> > > thanx
> > >
> > > Aaron