Re: burning Gecko drive

Jon, I'm not sure if this is true with all of the old BOSS machines.
I have a BOSS6 and it has a 2:1 reduction on all axis and 5 TPI
screws. It runs at about 120 IPM with the factory control which
equates to about 1200RPM at the motor. I think the later BOSS
machines may have had motors similar to the Superior Electric
M112/113 series.

~petev

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
> theokspindoctor wrote:
>
> >Thanks everyone for all the input!. Now I have a hope of at least
> >wiring safely! I will try the battery-bulb trick tonight...
> >
> >I am using a 75v 16 amp DC power supply.
> >
> >
> OK, you have a very serious problem. A number of people have had
> good performance with old BOSS retrofits using Gecko drives. They
> did need to use 70 - 75 V power supply, and the Geckos run REAL
> hot at that voltage and full current, but they work. Most have
gotten
> 60 - 90 IPM rapid feeds. I believe everybody used a 1:1 drive
scheme
> from motor to 5 TPI ballscrew.
>
> Does your machine have a lot of friction?
>
> I will note the old BOSS machines used motors designed as 60 Hz
synchronous
> motors to be run from a 120 V AC line. Running in half-winding
mode
> means the
> winding needs close to 60 V at 60 Hz to reach rated performace,
which would
> be at 72 RPM. This is the equivalent of 240 full steps/second, or
2400
> microsteps
> per second. So, you are already doing better than that. In other
> words, you start out
> with motors not designed from the ground up for stepper motor
performance.
>
> I still recommend the headphone test I mentioned earlier, as jagged
step
> pulse timing
> could definitely cause the problems you see.
>
> Jon