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Re: Torque needed to spin the secondary?



Tesla List wrote:

> Original Poster: "Marco Denicolai" <Marco.Denicolai-at-tellabs.fi>
>
> Hello all.
>
> I need to buy a motor to spin my 60 kg secondary form. It is a 1.8 m long
tube,
> 400 mm diameter, weights all together 60 kg.
>
> How many Nm torque the motor must supply to have it turning?
>
> I calculated 30 kg on 0.2 m, that is 300N on 0.3 m, that is 100 Nm. If we now
> think the weight is distributed on the whole 0.2 m radius and take the
integral
> for the radius length, we get to 50 Nm (one half).
>
> Is 50 Nm correct (some knowledge of mechanics needed, help!) ?
>
> Regards

Hi Marco...

you have to consider frictional values of the support structure at the bearings
more than anything else...   as far as the tube goes ...  it is in a sence
perfectly balanced. sooo  the only thing you will have to worry about in
that sence
is the original energy to get the mass to start moving ... and to what
speed you
want too.

The other forces that need to be addressed are the tangental tensions you
are going
to apply to the wire as it is fed onto the form... that force is going to
be the
strongest resistive force the motor will see...


Id say a 1/5 HP motor will do fine     even better yet    a 1/2" variable speed
drill  or hey....  a rotisarary motor used on BBQ's  ...

:)


Scot D