Re: [CAD_CAM_EDM_DRO] I'm curious

And I contend, a properly tuned (o'scope, critically damped) Gecko when
run within the power limits of the attached motor will exhibit far less
than 128 counts of following error, and even then, only on rapids. I
typically see about 4-5 counts error (~ 1/2 thou) or so, far less than
the allowable following error for rapids on the "name brand" closed loop
controllers. IF I get a following error with a Gecko, I'm either
accelerating too fast or otherwise have exceeded the capabilities of the
motor. On a typical system, 128 counts is somewhere in the areo of 12.8
thou following error, did I mention on rapids? If you are getting
greater than 128 counts of error on a G1 move, there is something
seriously wrong with your tuning or you're using too small of a motor.
The geckos are closed loop, a pulse received indicates to the drive that
it has to move one count, it corrects the position. Gecko's work, and
quite well, most of the machines I retrofit have 'conventional' closed
loop controls, against common logic, a Mach2/Gecko system typically
rapids 30-40% faster, cuts smoother, and is about twice as productive
versus pre retrofit. and these particular routers are not small, the
smallest I work on is a 6x10, my personal test bed is an 8'x12' router.
The argument is mostly semantics, as I, you, and many others on the
list, work within the performance envelope and get qute good results. I
do on the other hand, have no hesitation in moving up to the larger AC
servos, if the budget and performance needs justify it.


erie


erieRandy Brewer wrote:

>I define if from the Control Software stand point, mostly. If the drive
>faults because it didn't move would Mach have any idea where it was?
>
>If you tip into the position error neither the Gecko nor Mach attempts to
>makeup for the error. So long at you stay below the magic 128 both are
>happy.
>To me closed loop implies that there is some attempt to correct for errors..
>
>But like I said Mach and Geckos work well. I use both.
>
>
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>-----Original Message-----
>From: CAD_CAM_EDM_DRO@yahoogroups.com
>[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Erie Patsellis
>Sent: Wednesday, July 20, 2005 7:22 PM
>To: CAD_CAM_EDM_DRO@yahoogroups.com
>Subject: Re: [CAD_CAM_EDM_DRO] I'm curious
>
>Easy question Randy,
>Define closed loop.
>
>
>
>erie
>
>
>Randy Brewer wrote:
>
>
>
>>I did and still do not see where it is closed loop. Mach is not now and
>>will not ever be closed loop.
>>The Gecko being closed does not make the control system closed....
>>
>>
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