Re: [CAD_CAM_EDM_DRO] Clarification for microstepping requirement

I am a little late on this thread, but I just wanted to say that Richard
highlighted probably the most significant advantage of microstepping.

Resonance is a huge factor. I have tried a number of stepper motors, and all
of them suffer from resonance issues, and all at different frequencies! This
depends on motor construction -- rotor shape, weight, coil position, and a
gazillion of other factors that I am not aware of. Worse yet, there is no
way to figure out where exactly that resonance is going to bite you, and it
will vary even in stepper motors of the same model and same batch!
Microstepping does not eliminate resonance issues, but immensely minimizes
their adverse effects.

There is one more benefit to microstepping that I did not see mentioned that
is sort-of related: acceleration. Especially acceleration under load.

Of course, you should not get too carried away with microstepping - you
can't infinitely increase frequency of your pulses, so eventually agressive
microstepping will start limiting your maximum acheivable RPM.

Vlad

On 13 Dec 2005 13:45:55 +0000, Richard Garnish <rdg@...> wrote:
>
> The biggest benefit of microstepping in my view is that is greatly
> reduces the resonances caused by steppers in full-step mode. This
> resonance is sometimes enough to lose useful torque at certain step
> frequencies, in addition to the other undesirable effects of vibration
> on the machine it is attached to. Microstepping shouldn't be relied on
> for greater accuracy, but it it worth it for reducing resonance and
> getting more even torque response from the motor.
>
> Richard
>
> On Mon, 2005-12-12 at 21:20, ERIC QUARNSTROM wrote:
> > Hey all:
> >
> > I read the great FAQ's on this site regarding steppers and how they work
> and
> > microstepping. Very inciteful and I think I even understand how they do
> it.
> > What I can't quite figure out is why it is required. In one of the FAQ's
> it
> > says the primary purpose for microstepping is to eliminate the jerkyness
> > between steps. However, when I do the math on my proposed set up I come
> up
> > with a movement of the axis per step that is so small I can't consider
> it to
> > be 'jerky'. Therefore I am afraid I either didn't understand what I read
> > well enough or I'm missing something. My math is below and I welcome
> > comments.
> >
> > System statistics:
> > Lead screw with 10 TPI
> > 1:2 gearing between motor and lead screw
> > motor with 200 steps/revolution
> >
> > My math:
> > Every turn of the lead screw gear produces .1 inches of travel.
> > Every turn of the motor gear produces .05 inches of travel
> > Motor has 200 steps per turn of the motor so every one step would
> produce
> > .05/200 inches of travel
> >
> > In summary .00025 inches of travel per full step seems like a very small
> > amount of movement. So why would I need to divide that by 10 for a
> > microstepping drive?
> >
> > Thanks in advance,
> > Eric Q.
> >
> >
> >
> >
> > Addresses:
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> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
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> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...,
> timg@...
> Moderator: pentam@... indigo_red@... davemucha@...
> [Moderators]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
> aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it
> if you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
> sister site to the CCED group, as many of the same members are there, for OT
> subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING
> THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
> Yahoo! Groups Links
>
>
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>
>
>
>


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