Re: Power Supply for 4-axis CNC stepper driver

--- In CAD_CAM_EDM_DRO@yahoogroups.com, John Dammeyer <johnd@a...> wrote:

> Hi Dave,
>
> I'll stop here. I think you said you had 2.4V motors at 6A per

phase which

> you worked out to be 28.8VA or watts.
>
> Let's use the 25x rule and then say you need that 60V supply. When

you can

> demonstrate that a 60V, 28.8VA transformer can run your stepper motor at
> full torque and full speed with the same performance as a 240VA

transformer

> I'll buy you a beer. (BTW the 240VA comes from 6A * 60V * 66%). It

also

> has to be able to hold 70.7% of full motor name plate oz/in torque

at least

> two step positions which can be a real life scenario.
>
> Oh yes, and the transformer isn't allowed to let out any smoke.
>
> John Dammeyer

Ah... I don't think I ever run near maximum so I cannot say I get full
torque. I get movement and can run the machine(s)

I don't know if the transformer would smoke or the voltage would drop
off. Guess I have some testing to do so see if I'm not getting as
much as I could.

It is interesting that IIRC, the old rule of thumb was 66% of total
nameplate for current ratings, but we are no talking double that,
well, 1.8 times that anyway.

Maybe that is why so many people have failed on stepper conversions on
Mills ?

Dave