Re: HP plotter servo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Graham Stabler" <eexgs@n...>
wrote:

>
> > As I understand a Gecko 320 would probably work, but that is over
> > $100 each. I hope to build my entire machine for under $100.
>
> I realize it does not fit with the cheap approach although the
> reason I ask is that the inductance of the motors can make a
> difference to the control I was once told. Also anyone who already
> has a set of geckos would find it quite a cheap way to build such a
> machine. I am such a person.
>
> Here is the link to the microchip app note:
>
> http://ww1.microchip.com/downloads/en/AppNotes/00532c.pdf
>
> It would be great if this code could be modified to produce a
> general purpose step/direction controller for small servo control

on

> the cheap.
>
> Graham

If you feel like taking the time to reverse trace the board, I'll
send you a plotter.

As I figure, there are two servos. one for X and one for Y, plus a
stepper for the carosel, but it is a pressed can and would not need
to be very accurate. I haven't tried it to see what SPR it has.

There is another for paper feed, and like the carosel, this stepper
is pressed can.

The board is all thru-hole so it should not be painful like a multi
layer board to find where to connect for Step and Directon.

I just don't have the time for such a project.

There was a time where E-Bay was full of these for under $100.00 and
I traded 2 to a shop for two old laser printers.

One neat thing about the idea of making a servo driver is that unlike
motion control a PCB driller only has to get to the proper X/Y and
not there there per any prescribed path. That means both could just
spin till they reach the coordinate for that axis.

Makes the servo driver MUCH easier when you don't have to maintain
absolute postion control over the enrire move.

Dave


btw, as far as Geckos go, if you are planning on building any sort of
driver, don't buy a Gecko. it's like wanting to build a go-cart and
then getting a Coupe-deVille.