Re: [CAD_CAM_EDM_DRO] Driving the parallel port in WindowXP

> Sebastian,
>
> Thanks for the input. EMC looks like the right way to go, but I just
> don't see that many robust CAD programs for Linux. I don't want to use
> two machines or do a dual boot setup. Maybe I just haven't searched
> enough yet. What do most people use in Linux?
>

To first approximation, people don't use professional packages for CAD on
linux. There is an eclectic mix of stuff (written up at
http://www.tech-edv.co.at/lunix/CADlinks.html ), but only a few polished and
finished programs out there (BRL-CAD, perhaps VARKON).

I'm about to evaluate the professional package VariCAD (varicad.com), which
looks promising, and for nurbs blender (blender.org) or Rhino, if I can get
it to work under wine, which is unlikely. For blender I'll use this and emc
to do my g-code generation and emc for control:
http://web.media.mit.edu/~neilg/fab/dist/cam.py

> My main purpose is to design a CAD application that simplifies the whole
> design process for simple operations. For example, if I want a quarter
> circle milled, I just want to be able to position to cutter at the
> center and tell the software "cut a quarter circle with a diameter of X
> here". One of the problem I see with current CNC software is that it
> takes a just as long to do something real simple as it would take to do
> something more complicated.
>

I think this guy is doing something similar.
http://gcam.js.cx/
He hasn't published anything, which makes it really damn hard to see what he's
actually up to.

I strongly suggest you consider writing something you can bolt onto/into emc.
(I think) the emc developers have already done quite a bit of the heavy
lifting, figuring out the real time os stuff, parallel port and machine tool
descriptions, g-code interpretation. If you leverage all that stuff, you
could be done months earlier. And your users will have emc working if they
want to do something more sophisticated. Plus, if it's something emc could
use, than it should be written, and if it's something emc has already, then
you can add refinements to what they've got.

Also emc has a community of developers and users. Never underestimate the
value of an existing community. (Also this way you'll avoid writing scads of
documentation, creating a mailing list, forum, website, etc. etc. etc., all
of which is necessary, but not half as fun as coding/machining.)

One thing to consider is your postion as a single-person developer. Even if
you write some software that's damn useful, it may not stand out next to all
the other small projects out there. (And there are so many little projects
out there it's difficult for users to pick out the ones that work and are
actively being developed.)
If you build it into emc, people will end up using it.

Rule one for programmers is "reinvent the wheel". Which is why you see so
many half-built wheels out there, and so few finished projects.

I would suggest you look very carefully at emc, see if the developers are
approachable, look at the code, and then decide if you want to build onto
emc, or code something separate.

> I also wanted to write a visual, easy to use rotary table driver to make
> gear cutting, etc. simple and fool proof.
>
> Lastly, I own the rights to a product called the Frog, which is a simple
> single axis programmable controller which also supports thread cutting.
> I'm thinking of porting this with a good UI to a PC based system
> (Windows or Linux) and expand it to support more axis. It may become the
> basis for a "simple CNC language". I'm just kind of thinking out load.
>
> Lester pointed me to Mach, and I can't tell if it is Linux or Windows
> based, and if it has any CAD capabilities. I may fire off an e-mail to
> them.
>
> Lastly, which vendor to you recommend of off-the-self multi-axis driver
> and power supply already assembled in an enclosure?
>

I don't know, I built mine from L297 and L298 chips, and I'm going to use one
of the circuits at pminmo.com for a while. For a power supply, it depends
on your requirements. I don't know if I'll need more than 12 volts, so I may
use 1-3 computer power supplies and an old PC case as an enclosure. Old PC
cases are basically free, and often come with fans and 5V+12V power supplies.

The other list members really know the commercial hardware motor driver stuff.
Guys?

> Thanks,
> Kory
>

Note that I am really a novice at this stuff, and so I am reasoning from first
principles and my preconceptions as much as anything.

Regards,

Sebastien