Message #23413 Re:DeskNC - CNC Pro 3x as fast as EMC???

To: kleinbauer@...

Let me try to clarify what I said in #23413. Also be aware, I've never tried
to sell anything in this list. I have recommended products that I have
purchased and use.

First, a little bit about what I do. I'm an electronics engineer /
programmer that worked for a fortune 100 company up until 3.5 years ago when
I got fed up with the big city and moved to the Ozarks to work for myself. I
design electronics and write software for a living. I do CNC for a hobby.
It's likely that several people on this list have computer products that
have the results of my work inside them.

Building a stepper motor controller is not a difficult task when dealing
with a low current and low voltage standard bipolar drive. Unipolar is even
easier but I prefer bipolar.

Buying an L297 qty 1 from Mouser is $5.41
Buying a PIC16F870 qty 1 from Digikey is $4.63

Since the PIC microcontroller can replace the L297 easily, and add new
features to the controller, it seems to be very logical to me. The L297 is
the 'logic' device in the circuit. Anytime you can replace a hard coded
device with a more flexible, reprogrammable, cheaper device it is logical.
Once you have the standard stepper drive working, you can then add new
features like microstepping by just changing the software in the device. You
can also add encoder feedback to the microcontroller circuit by simply
adding 2 resistors, the encoder and some code. Let's see you do that with an
L297. Add an L298 for $3.20 and you have a 2 amp 40 or so volt controller.
Want higher voltage or current? Just use Mosfets intead of the transistor
based L298.

But, the time spent building such a controller usually isn't logical
economically. Unless you plan on selling it to others as a commercial
product. It would cost more in time for me to build one than it would to buy
a Gecko or other low cost unit.

For someone that wants to learn something, then the value of the education
is worth far more than the difference in cost. I certainly wouldn't want to
discourage experimentation for the pursuit of knowlege.
But sometimes it is just more logical to buy something that works out of the
box than to spend time building it.

later,
Larry E.

----- Original Message -----
From: <kleinbauer@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, April 19, 2001 8:22 AM
Subject: [CAD_CAM_EDM_DRO] Re: DeskNC - CNC Pro 3x as fast as EMC???


> Hi,
> I am only putting forth some obsevations. I also have a problem
> with people constantly hawking there wears VIA this conference. They
> tell people certain ideas are a waste of time, only to have a buy
> this solution. I am sure the man who designed Gecko products started
> out using simpler designs. If building it yourself is a waste of
> time, then I say forget retro fitting and buy a new machine!
> Message 23413 is what I am talking about. You don't want to build
> a controller use a PIC instead. What logic!
>
> John