Re: [CAD_CAM_EDM_DRO] Newbie question. Second try

Hi Antonio,

Sorry you didn't get an immediate reply. I don't recall seeing this
exact post, but I'll try to give you a few answers, below:


antonio-ximenez@... wrote:

>
> Hi, One week ago I posted a question, but something have not posted
> any reply.
> If the question is dumb or not interesting I apology.
>
> I have 3 drivers based in L297 L298 combo.
> The first thing different an other combos is the next phrase in the
> operation manual "The new SD1V1.2 incorporates half step shaping for
> 95% torque of full step mode"

Haven't heard of "half step shaping" Do you have a URL for the SD1V1.2?

>
> I have got 4 surplus motors with the next technical data:
> 150 oz-in Nominal, 4.5V, 1.4A, 2º/step, 6 Wire, Nema 34, Single
> Shaft.
>
> I am planning wiring this motors in half winding based in earlier
> recommendations in this group.
>
> In Mariss Power Supply tecnical white Paper, the recommendation is "
> THE Driver will always draw less then 2/3 of the motors rated current
> when is half winding "

SO, three motors, 1 A each, a typical 4A linear power supply (xfmr,
rectifier and cap) should be easy to do/get.

>
> With the above parameters what is the suitable amperage in order to
> configure the chopping subsystem (PWM) ?
> 1.4 Amp or (1.4*2)/3 = 0.93333 .
> If the amperage is < 1.4A am I lossing torque ?

The motors don't draw it all the time, the power supply will handle it,
the motors get what they need.

> What´s the matter if I set Vref in order to get 1.4 amp ? Could I
> fried the motors ?

Possibly.

> What is the meaning of half step shaping for 95% torque of full step
> mode.

Unknown. A guess, I'd say they are changing the current between the two
winding and single winding steps.

>
> Insulation and Grounding
>
> I am planning wiring the motors with 18 awg shield 4 wires. The
> question is... The aluminion foil of the shield must be connected
> only in one end
> What end ?

> The motor case end or the drivers and Power Supply case, exactly in
> the same point where is attached the power ground cord.
>
> Thanks in Advance

I'd tie the shield to the P.S. ground. However, 18 ga. is a little
light if you have a long wire run.

HTH

Alan KM6VV