RE: [CAD_CAM_EDM_DRO] Re: Stepper controller / driver for powerfeed

Here's one other low cost option that may work for you but will require
a bit of programming (or a friendly request to Aaron, the designer.

The link here below shows the schematic of the AVR based Stepper driver
http://www.bright.net/~agarb/STMD/Photos/Full%20Size/Schematic_AVR_old.g
if

With a small software change, the dip switch step selection can be
shifted to get rid of the brake function. Then ADC0 could be used as an
analog input. When 0, normal step/direction works. When > 0 the A/D
value could become the step rate times a constant eg. 1..1023 * 24 for
24 to 25000 steps per second.

I haven't looked at the code to see if there's room for the stepper
frequency output but if so, if would give you a nice 3 Amp, 50 Volt
stepper driver that could eventually be tied to an ELS or MACH3 but
initially could be a simple drive. A pot and a switch on the direction
line round out the package.

Write Aaron by clicking on the (email me) link at the bottom of the page

http://www.bright.net/~agarb/STMD/AVR_STMD.html

As I said above, I don't know if there's room in the AVR device for this
and the code is written in assembler so obviously it's a bit more work
that if it's done in a few lines of C language but I just finished a
test of the concept using the dsPIC 30F2010 project board that I picked
up for the latest Circuit Cellar Design Contest.

I had already implemented the basic Electronic Lead Screw code to have
the stepper motor be driven at any ratiometric speed relative to the
spindle speed but hadn't touched it for a while because of other
projects etc. It was pretty easy to add the A/D pot reading code to
translate into a jog speed to make the stepper turn. The project board
has a trim pot on it and a pushbutton so no extra hardware was required.


Now granted, this dsPIC is far more complicated than a 555 timer circuit
for just stepper motor speed but it would be easy enough to add extra
hardware to drive the stepper windings directly just like the AVR board
above. But I think Aaron's STMD might be just the ticket with a few
simple changes.

John Dammeyer

Side note. I noticed on the schematic and the FAQ sheet that there was
a POT once but is listed as optional and in the FAQ as not used.
Perhaps this input could be used for this.

>
> Ok these options are too expensive and probably too complicated for
> what I want. This unit is for my little 9x20 cross-slide on my lathe.
> A speed dial, with forward/reverse switches - that sends a pulse to
> my stepper driver board will do the trick.
>
>
>
>