RE: [CAD_CAM_EDM_DRO] Re: Gecko differences

Dave:

As I understand it:

If you can get the rapid rates you want/need with the regular
10-microsteps/step using the Geckos WITHOUT the multiplier, you don't need
the multiplier.

If you r pulse generator(controller software, such as Mach2, in my case)
can't pulse fast enough to get the rapids you need, then you can use the
Gecko with the multiplier.


It works like this:

Let's say you have steppers motors, with 200 steps/rev. Also, that you axis
works out to needing 20 revs of the motor for 1" of travel.

Using a microstepping Gecko drive, you will need to issue 20 * 200 * 10(10
microsteps/step) pulses for each inch of travel. This works out to 40,000
pulses per inch of travel.

Now, if you want to get 60 IPM(1 inch/sec) rapids, you will need 40,000
pulses per second. This is within the range of some controllers, but not all
of them. Asuming you were using Mach2, you could get 45000 pulses/sec. In
this case, you wouldn't need the step multiplier.

On the other hand, let's say your controller could only put out 25,000
pulses/sec. This would not allow you to have the rapid rate you want, as you
would only get 25,000/(40,000) inches/sec, or .625 in/sec.

So, you could use the lower pulse rate,, and a Gecko with a multiplier. Set
to "10", the gecko multiplier does just that, it multiplies each pulse it
receives by 10. So your 25,000 steps/sec would become 250,000 steps/sec.
This would allow for 6.25 in/sec, or 375 IPM. (Assuming your motors could
drive your axes this fast).

So, what is happening is that the gecko is multiplying the steps you send it
by 10, and then using each of these new steps as a microstep.


You lose some theoretical resolution, as you are only sending a step for
every 10 microsteps the motor will ultimately get(and you have to send the
steps you send one at a time, you can't send .1 of a step-at least until we
get this quantum mechanics thing figured out :)), but the benefit of
microstepping, as I understand it, is NOT more resolution between "whole"
steps, but the smoothness at which the motor moves between those stps.

I hope I got this right, and that it I helpful to you. It took me quit a
while to figure ths out.

I love gecko drives(the drive) and Geckodrive(the company), but their
website could explain things a bit more clearly, in my opinion.


Andy Wander
Verrex Corporation


-----Original Message-----
From: turbulatordude [mailto:davemucha@...]
Sent: Friday, November 12, 2004 10:50 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Gecko differences



--- In CAD_CAM_EDM_DRO@yahoogroups.com, Stephen Wille Padnos
<spadnos@s...> wrote:

> turbulatordude wrote:
>
> >Hi all,
> >
> >I am interested in the recent discount of Gecko drives and was
> >pondering the idea of using servos on a machine.
> >
> The 340 and 210 have the G901 pulse multiplier on their inputs.

This

> allows them to multiply incoming pulses by 2, 5, or 10 (or 1), so

the

> motor moves faster. It also gives the ability to work with a

common

> ground or a common supply for the optoisolators.

Any idea on what type of machine the multiplier is needed ? Or is it
more for higher resolution or faster rapids....

I'm trying to see the added benifit for my applications.


Dave