CAD CAM EDM DRO - Yahoo Group Archive

Re: Clarification for microstepping requirement

Posted by jeffalanp
on 2005-12-12 15:44:57 UTC
Hi,
With your [do you get there "all-at-once" or gradually] senario,
don't forget, that with the "all-at-once" FULL step mode, you
actually OVERSHOOT the FULL STEP point. After reaching the maximum
point at overshoot, you start moving back towards the full step
point, but again, because of momentum, you overshoot again, though
not so much. This oscillation around the full step point can take a
while to die down, and while doing so, transfer its vibrational
energy directly to your machine.

So, instead of a FULL step, move a smaller step (1/8th, 1/10, or
1/16th for example). Your acceleration to get to the closer point is
less, so your overshoot is less, so less ringing and vibration, and
less time to wait for vibrations to disipate so you can actually move
faster in many cases, and power is not wasted trying to bring the
motor to the FULL step point.

Jeff


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Andy Wander" <awander@v...>
wrote:
>
> Eric:
>
> It's not how many positions you have(in this case, every .000025"
> instead of every .00025"), but rather how smoothly you get from one
> position to the next. While you CAN stop in between the "full"
steps,
> your position will NOT be guaranteed to be so many 1/10ths of a full
> step. Rather, it is that while you are traveling, going from full
step
> to full step, do you get there "all-at-once" or gradually(well, of
> course, you DO get there gradually, but I am referring to what the
drive
> is telling the motor to do.
>
> It's kind of like a dimmer on a light. If "OFF" is one full step
> position, and "ON" is the next full step position, do you "switch
the
> lights on" or do you dim them up gradually and smoothly.
>
> From what I understand, the dimming up, as opposed to the switching
on,
> can make your light bulb filaments last longer as there is less
stress
> imposed by a gradual change in applied voltage.
>
> The situation with the steppers is that at certain speeds you can
have
> nasty resonances cause by the "switching" of the motor voltages, and
> that by gradually changing the voltages(micro-stepping) you are much
> less likely to have those problems.
>
>
> Andy Wander
> Verrex Corporation
>
> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of ERIC
QUARNSTROM
> Sent: Monday, December 12, 2005 4:20 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Clarification for microstepping
requirement
>
> 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.
>
>
>
> This communication including any attachments, are intended
> for the exclusive use of the addressee(s) and contains
> confidential or copyrighted materials. Duplication,
> distribution or reproduction is strictly prohibited by law
> without written permission of Verrex
>

Discussion Thread

CalBoy101 2005-09-07 15:01:25 UTC Ball lead screw backlash problems R Rogers 2005-09-07 15:53:06 UTC Re: [CAD_CAM_EDM_DRO] Ball lead screw backlash problems jacoby01 2005-09-07 17:40:38 UTC Re: Ball lead screw backlash problems CalBoy101 2005-09-08 09:48:21 UTC Re: Ball lead screw backlash problems CalBoy101 2005-09-08 12:55:38 UTC Re: Ball lead screw backlash problems ERIC QUARNSTROM 2005-12-12 13:20:30 UTC Clarification for microstepping requirement Andy Wander 2005-12-12 13:30:01 UTC RE: [CAD_CAM_EDM_DRO] Clarification for microstepping requirement Crs Hawk 2005-12-12 14:24:22 UTC Re: [CAD_CAM_EDM_DRO] Clarification for microstepping requirement jeffalanp 2005-12-12 15:44:57 UTC Re: Clarification for microstepping requirement Paul Kelly 2005-12-12 17:43:52 UTC RE: [CAD_CAM_EDM_DRO] Re: Clarification for microstepping requirement ericq47 2005-12-12 17:46:28 UTC Re: Clarification for microstepping requirement John Dammeyer 2005-12-12 18:02:33 UTC RE: [CAD_CAM_EDM_DRO] Re: Clarification for microstepping requirement Richard Garnish 2005-12-13 05:55:33 UTC Re: [CAD_CAM_EDM_DRO] Clarification for microstepping requirement juan gelt 2005-12-13 11:03:49 UTC Re: [CAD_CAM_EDM_DRO] Clarification for microstepping requirement Vlad Krupin 2005-12-17 07:37:22 UTC Re: [CAD_CAM_EDM_DRO] Clarification for microstepping requirement