Re: oz*in NOT oz/in

Thanks,

That's one for the library.

It also means I can gear up for speed.
My timing gear set offers 5,200 steps per inch. I can trade that for
speed and not lose much resolution. I doubt my set-up has a
posistional accuracy of 0.0002" and I don't need that much anyway.


Dave

--- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...> wrote:
> Dave,
>
> A step motor's torque is the inverse of its speed. Here's why:
>
> The motor winding has inductance (L). Inductance has a property
> called inductive reactance. It is measured in Ohms and is
> proportional to frequency (step rate).
>
> This means if the step rate doubles, inductive reactance also
> doubles. According to OHm's Law (I=V/R), current thru the winding
> will be halved. Torque is directly proportional to current, so it
> will be halved as well.
>
> Power is speed times torque. If speed is doubled and torque is
> halved, the product of the two (RPM * oz-in) remains the same. This
> means a step motor's output power is independent of speed. It has
> constant output power.
>
> Mariss
>
> --- In CAD_CAM_EDM_DRO@y..., "dave_ace_me" <davemucha@j...> wrote:
> > Hi Doug,
> >
> > I'm on real shakey ground here so I am only going by what seems
to
> > make sense to me.
> >
> > If one has a block of some weight with a thread in it and a
> threaded
> > rod is in that hole. a certain amount of rotational force (foot
> > pounds) will be needed to lift that weight with that TPI thread.
> >
> > a finer thread would need less torque.
> >
> > at least that is how it appears to me.
> >
> > now, the fact that stepper output force is not linear over the
> speed
> > range, now that is something else.
> >
> > Dave
> >
> >
> > --- In CAD_CAM_EDM_DRO@y..., Doug Fortune <pentam@c...> wrote:
> > >
> > > Those of you who are trying to work out
> > > torque vs table push (using units analysis)
> > > will never get it to work out because:
> > >
> > > torque is measured in 'force*lever arm'
> > > in other words, oz*in lb*feet N*m
> > >
> > > etc, NOT oz/in , lb/ft etc.
> > >
> > > (Yes I know oz & lb are not exactly units
> > > of force, we should be using Slugs but I'm
> > > afraid that will lead to even More Confusion!).
> > >
> > > Doug Fortune
> > > http://www.cncKITS.com NEW -> 1 KW power supply kits
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > .