Re: moving Bridgeport steppers with Gecko drivers - help!

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:

> theokspindoctor wrote:
>
> >I am in the painful process of retrofitting a Boss 6 Series 1
> >Bridgeport mill using the original stepper motors and new Gecko

201

> >drivers with a Galil stepper board and CNC Lite controlling

software

> >from Cam Soft Inc.
> >
> >At this point I can move the motors at a slow speed the distance

I

> >specify in diagnostic mode and am able to write G code programs

to

> >get proper movement. However I cannot seem to change the

feedrate

> >and the rapids are very slow.
> >
> >The motors are wired according to Les Newel's suggestions (thanks
> >Les!) in half winding mode using only 2 of the 3 phases on the

Gecko

> >drivers.
> >
> What 3 phases? The Gecko 201 is a 2-phase bipolar driver. You

must mean

> only using 2 of the 3 wires of each phase of the MOTOR. That is

correct.

>
> > Am using a 340Kohm resistor although Les recommended no
> >resistor. The resistor limits the amperage to about 6 amps, I

think.

> >
> >Does it matter that the motors are 200 steps per revolution and

the

> >Gecko drives 2000 steps per rev?
> >
> >
> The Gecko is a x10 microstepping driver. With a 200 full-step per

rev

> motor, then you need 2000 step pulses to get a full revolution.
>
> >It seems that I cannot jog, but can move pitifully with G code
> >programming.
> >
> >Any suggestions?
> >
> >The tech help at Cam Soft has not been able to solve the problem

and

> >Mariss at GEcko Drives is on vacation until next week.
> >
> >
> Is the problem that nothing you do on the software gets a faster
> movement, or
> does the motor clatter and lose sync? If it is a case of the

software,

> has the
> setup of the software been told it takes 2000 steps/rev? I don't

know

> CNC Lite, so I can't go much farther than that.
>
> I will mention that I am running a stepper-driven machine with

Gecko 201A

> drives and my Universal Stepper Controller at 48,000 (micro)steps

per

> second,
> which works out to 1440 RPM. You pretty much can't do that with a
> software-only
> solution.
>
> Jon

Thanks Jon,

I have 8 wire motors with 4 "coils". They are wired with 2 of the
coils not connected and 2 of the coils connected to the Gecko drive.
The ones connected are "across" from each other I think. The wires
go to the 4 connectors on the Gecko drive labelled phase a b c and
d. This is probably a half winding or parallel wiring I think. We
have the 340kOhm resistors across the current set terminals but do
not have the capacitor Mariss describes across the power.

Also, when I tried to wire the motor using the 8 wire parallel setup
described in the white paper from Gecko it burned out the drive.

What does 1440 rpm equate to in terms of movement of the axis. I
have a 2:1 gearing with a 5 pitch lead screw. 10 rotations of the
motor will move the axis 1 inch?? considering these specs? 1440 rpm
would then be 144 inches per minute?

Do you have a 1000 oz/in motor as used in the Bridgeport with your
Gecko driver?

Thanks!

Keith Clark