hard disk motor

Both the spindle motor and head actuator are servo motors with perm-magnets.
You could look up a servo controller chip datasheet with google.
I doubt the motor will position accurately, it is not designed for that.

"Andrea Mazzolari" <andrea.mazzolari.DeleteThis@gmail.com> wrote in message
news:1182679612.328526.137820@p77g2000hsh.googlegroups.com...
> Hi all, i need a motor with a high rotational accuracy, so i 've think
> to re-use a motor of a hard disk.
>
> Here are some questions:
> 1) considering the smallest rotation permitted with a motor of this
> type, which is the corrisponding rotating angle?
> 2) where can i find some tutorial/guide/or any other information on
> how to write a software to control an hard diks motor ?
>
 >> Stay informed about: hard disk motor 

Arno Wagner <me.TakeThisOut@privacy.net> wrote:
> Previously Andrea Mazzolari <andrea.mazzolari.TakeThisOut@gmail.com> wrote:
>> Hi all, i need a motor with a high rotational accuracy, so i 've
>> think to re-use a motor of a hard disk.
>
>> Here are some questions:
>> 1) considering the smallest rotation permitted with a motor of this
>> type, which is the corrisponding rotating angle?

> Huh? This is not a stepper-type motor....

The rotation motor is, the head actuator isnt.

>> 2) where can i find some tutorial/guide/or any other information
>> on how to write a software to control an hard diks motor ?

> You cannot. You have to build your own driver electronics, since
> a HDD will not spin the motor unless it can also get the rest to work.
> Or it will spin-down pretty soon again.

You can obviously replace the microcode on the logic card.
 >> Stay informed about: hard disk motor 

"zappo" <zappo.DeleteThis@zappo.com> wrote in message
news:467edb46$0$28962$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
>> Huh? This is not a stepper-type motor....
>
> The rotation motor is, the head actuator isnt.
>

NEITHER is a stepper motor.

Actuator motor used to be a stepper in drives like ST225 (20 MB formatted),
but even 100 MB generation already could not be implemeted on a stepper.
 >> Stay informed about: hard disk motor 

Previously Alexander Grigoriev <alegr.TakeThisOut@earthlink.net> wrote:

> "zappo" <zappo.TakeThisOut@zappo.com> wrote in message
> news:467edb46$0$28962$5a62ac22@per-qv1-newsreader-01.iinet.net.au...
>>> Huh? This is not a stepper-type motor....
>>
>> The rotation motor is, the head actuator isnt.
>>

> NEITHER is a stepper motor.

> Actuator motor used to be a stepper in drives like ST225 (20 MB formatted),
> but even 100 MB generation already could not be implemeted on a stepper.

Indeed. The spindle motor is what is called a "servo controlled DC
motor". To the uninitiated it may look like a stepper, but it is
not. It cannot really be used for positioning without severely
misusing and potentially overloading its coils. The driver circuit on
the HDD PCB cannot do this. It is designed to provide a very smooth,
linear spin at a specific frequency.

One main difference is that a spindle motor has a "stepping angle"
of 120 degrees, while in a stepper 1.8 degrees or the like are typical.
Also steppers are designed to be able to hold a specific position
very precisely and against force. Spindle motors are not.

Arno
 >> Stay informed about: hard disk motor 

Arno Wagner wrote:


>Indeed. The spindle motor is what is called a "servo controlled DC
>motor". To the uninitiated it may look like a stepper, but it is
>not. It cannot really be used for positioning without severely
>misusing and potentially overloading its coils. The driver circuit on
>the HDD PCB cannot do this. It is designed to provide a very smooth,
>linear spin at a specific frequency.
>
>One main difference is that a spindle motor has a "stepping angle"
>of 120 degrees,

Because it's a multi-phase brushless design, not because it "steps".

>while in a stepper 1.8 degrees or the like are typical.
>Also steppers are designed to be able to hold a specific position
>very precisely and against force. Spindle motors are not.
 >> Stay informed about: hard disk motor 

Alexander Grigoriev <alegr.DeleteThis@earthlink.net> wrote
> "zappo" <zappo.DeleteThis@zappo.com> wrote

>>> Huh? This is not a stepper-type motor....

>> The rotation motor is, the head actuator isnt.

> NEITHER is a stepper motor.

Wrong with the rotation motor.

> Actuator motor used to be a stepper in drives like ST225 (20 MB formatted), but even 100 MB
> generation already could not be implemeted on a stepper.

Irrelevant to the rotation motor.
 >> Stay informed about: hard disk motor 

Previously chrisv <chrisv RemoveThis @nospam.invalid> wrote:
> Arno Wagner wrote:


>>Indeed. The spindle motor is what is called a "servo controlled DC
>>motor". To the uninitiated it may look like a stepper, but it is
>>not. It cannot really be used for positioning without severely
>>misusing and potentially overloading its coils. The driver circuit on
>>the HDD PCB cannot do this. It is designed to provide a very smooth,
>>linear spin at a specific frequency.
>>
>>One main difference is that a spindle motor has a "stepping angle"
>>of 120 degrees,

> Because it's a multi-phase brushless design, not because it "steps".

Indeed. And while it can be made to step, but it is not really
suitable for it.

Arno
 >> Stay informed about: hard disk motor