Re: Stepper Motors

Just posting the ratios of the figures provided by Mike Cheney for
the convenience of those who would like to respond to his questions.

U unipolar 4.3 3.0
S series 3.0 2.1
P parallel 6.0 3.5

ratio P/U 1.4 1.2
. P/S 2.0 1.7
. U/S 1.4 1.4
. S/U 0.7 0.7

From previous posts, I thought that the rated current of 6 wires
steppers is the unipolar (U) current which is the same as bipolar
parallel (P), ie. P/U = 2 and the bipolar series (S) should be the
same as the rated (unipolar) current, ie. S/U = U/S = 1 ?

Peter


"Mike Chaney" <michaelchaney@b...> wrote:

> I've been lurking - and learning - for several weeks now and the

time has

> come to join in. Having been slowly drawing up a specification for

the

> conversion of a Taiwan mill/drill to CNC, I finally decided to

order a 5A

> 3-axis driver from Camtronics. This was on 11-11-01, the day after

Dan

> Mauch announced that he had sold out!
>
> I had, perforce, to design my own, not too difficult after a

lifetime in the

> electronics industry before changing course completely (see
> http://www.shaymaker.pwp.blueyonder.co.uk .)
>
> There are some aspects of stepper motors, however, which puzzle me

a little.

>
> The motors I am using are specified as follows:-
>
> Current rating per phase
>
> Motor #1 Motor #2
>
> Unipolar 4.3A 3A
> Bipolar series 3A 2.1A
> Bipolar parallel 6A 3.5A
>
> Am I right in thinking that these are maximum currents before

magnetic

> saturation occurs? The figures for Motor #2 don't seem to make a

lot of

> sense compared with Motor #1.
>
> When setting up the driver, with the stepper stationary and the

relevant

> winding drawing current, which value do I use in each instance?
>
> I'm sure there are simple answers, but I seem to be going round in

circles

> getting nowhere.
>
> I'd appreciate any help you can give.
>
> Many thanks,
>
> Mike Chaney