Re: new to me Bridgeport Series 1w/boss3, bunch of questions....

My machine too is a 1977, Boss 6 machine. The Nema 42 motors are 6
wires, you only hook 4 to a gecko or LARKEN drive. Geckos only can put
out 7 amps, it takes 8amps+ to get a decent speed from this heavy
slide table.

My machine runs at 120+ ipm, the slide weighs over 300 pounds. I am
currently using turbocnc software.

COnversion is up to you, I did mine cause I needed single phase to
operate my machine. It has a 3 phase controls transformer in the rear
cabinet to run the steppers. It can not to my knowledge be converted
to single phase. I purchased a 2kva 220-48vac transformer (dual 24 ac
in series) installed it for the drives (makes 68vdc with bridge and
capacitors), installed a toshiba single phase to 3 phase inverter
drive for the head. then started pulling out wiring and redoing it to
my hand drawn schematic.

I sold the boss hardware for $250, spent $1200 on the conversion.

The motors wire into the bottom terminal strip in the tape drive
cabinet. X1-X6, just find the common wires and leave them on the strip
isolated and seperate, hook the wire end coils up to the 4 bipolar
connections on the drive. YOU are converting the motors from a
unipolar arrangement to a bipolar. You are making the drive run from 8
amps per phase x 4 coil ends to 8amps series. (like 8x2 coils)

One thing, the original drive uses a reactor type coil to limit the
current on the drives. It liked to have drove me crazy till I throwed
it out. I stripped the cabinet, redone it. The 220-120 transformer is
plenty large enough to drive a pc.

Home shop machinist has a excellent article, kinda expensive thou.
They have schematics of the motors on there.

Larken:
I used the Larken drives cause they have normal components in Sockets
and are home-repairable. I have had NO problems with them.
Geckos:
The inertia of the slide actually generates back into the capacitors,
And use the voltage dump circuit Mariss has on his sites. Use heat
sinks with fans and heat sink grease on the backs of the geckos. They
ran for 1 year on weekends bolted to the 24"x30" sink on the back
door. The internal sinking of the geckos is accomplished by clamping
the circuit board with small bolts holding the fet's flat on the heat
sink. The ones that failed were not clamped properly. HEAT with
voltage rise caused a run-away of the fets. I bought 4 of them as
replacments till I figured that out. The power reduction scheme is the
best I have ever saw, they shift back to conserve power nearly
immediately after stopping. They are a small compact drive you can not
work on thou.

They are however a excellent drive for lighter tables-slides. I
noticed they have plenty of different Names silk screened on them.

Even with it being a rocky road I am happy with my machine.

David Cofer ibewgypsie@...




--- In CAD_CAM_EDM_DRO@yahoogroups.com, "mueller914" <mueller914@y...>
wrote:

> It's an older 1977 model and seems to work okay (still at the
> original shop and not at home yet), I am looking forward to playing
> with this machine and making chips, it's many, many times bigger and
> badder than my 3-n-1 Shoptask for sure!!!!!!
>
>
> Questions:
> Where can I find information on what stepper motors should be
> installed?
>
> Should I change out the Boss 3 controller and run the original motors
> using a PC and Gecko's or is there a way I can run the machine from a
> PC utilizing the stock electronics?
>
> Sooner or later I would like to change it over to a Servo CNC since I
> have a Camtronics(?) powersupply and Gecko's for my 3-n-1 mill/lathe.
>
> Should I be able to use my existing power supply and Gecko's??
>
> thanks,
>
> Mike Mueller
> Antioch, CA