RE: [CAD_CAM_EDM_DRO] Re: How to choose?; was "parallel port finally obsolete?"

SheetCAM has a Linux version, BTW


Andy Wander


-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Jon Elson
Sent: Monday, February 27, 2012 9:48 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Re: How to choose?; was "parallel port finally obsolete?"

scyvt wrote:

> Many respondents have assumed that because I was a Mac aficionado that I was determined to use a Mac to control a cnc machine. That would be pleasing, but I am reconciled that presently it is not practical, and never meant to impose that restriction on this discussion.
>
> There are two sides to the MacUser coin: one is the pleasure of concentrating on the driving without having to do much fussing under the hood, or worrying much about potholes such as malware. The other is distaste for anything Microsoft, which in my case is pretty severe,
>
>

Yeah, about the same here! I run Win 2000 as a guest OS under VMware on
several
Linux systems so I can run some old CAD applications that so far have no
equal
under Linux. Otherwise, everything I do is in Linux.

> Your path of LinuxCNC saves me the displeasure of running Windoze for motion control, but - I think - demands that I spend a fair bit of time under the hood until everything is running properly.

Nope. If you want to run steppers via software, you can get it running
in an afternoon!
Well, maybe that's just a LITTLE bit of an exaggeration, but not much.
Downloading and installing LinuxCNC on a suitable PC is pretty easy.
Download a rather big file and burn as an ISO image to a CD or DVD
with a suitable CD burner program. Boot this CD on the prospective
PC and run the latency test program to verify the hardware is acceptable.
Let it run for a while to make sure there are no long-term latency
issues. If that looks good, click the install icon, and in 20 minutes
LinuxCNC
is loaded. Now, there is a stepconfig wizard that I don't know a lot about,
but it creates the config files for typical 3-axis machines by asking some
questions. You probably won't need to make any changes to that config,
but you can edit the files if such is needed.

I typically load this system in under 30 minutes and have it running on
a number of computers, some of them not used for CNC at all, just because
I know it.

Now, if you want to run servos, that can take a little longer, but there are
sample configs files included on the CD for a variety of typical systems.
With these, there are a few standard adjustments needed like encoder
resolution and max speeds. Then, you have to tune the servo response
based on the characteristics of the movement. There is a program
that brings up a digital scope so you can get real-time plots of
commanded vs. actual movement, which greatly eases the
tuning process. So, generally no special test gear is needed.

> Assuming that OSX has allowed my brain to atrophy, do you assert that EMC has evolved to the point where it can really be used by the "brain dead"?

Yes, the old "Brain Dead Install" was a huge step forward, but was
created by a very
small group, and didn't have wide enough testing. Now, half a decade
forward, the
Ubuntu group has tested it on thousands of models, and it is much more
reliable.
There ARE some systems that is just doesn't want to install properly on,
or that
have rotten latency, that's why we have a supported hardware list that
tells what
works, and what doesn't, or at least needs some special setting.

> If so, that's great, and you've got me half convinced - but what then about CAM? There's a host of CAM applications listed on the linuxcnc site, but no way to tell whether any of them would compare in capability to popular Windows apps, like, say, SheetCam. Do you remain in Linux for your CAM work, or revert to Windows for that? And BTW, what do you use for 3D CAD?
>

I don't do much 3D. And, so, I have little use for traditional
CAD/CAM. I have my own
flavor of CAM, a bunch of C programs that write the G-code for the
typical operations
I do so often, like round holes, rectangular holes, drill a pattern of
holes at specific
coordinates, and so on. I do all of that in Linux, generally on the CNC
machine.
I have made most of these programs public on my web site
http://pico-systems.com/gcode.html
I need to update this page, it is totally ancient.

I do have Bobcad/CAM, not a package I can recommend, but there are
MANY. And,
since LinuxCNC takes such a plain vanilla version of G-code, it is
compatible with
most CAM systems.

> Perhaps I should mention that my first machine to convert is an 80"s vintage BOSS Bridgeport; there is very little mechanical work other than replacing the steppers.
>

Well, that is getting up to the size machine where you ought to at least
think about
servos. NEMA 42 servos are a drop-in fit, I did one at Roland
Freistad's place
some years ago. I had the machine running in one day from a cold start, at
a well-equipped place but not MY shop, so I had to constantly hunt for
bolts,
etc.

But, if you want to use steppers, new units should be fine, too.

Jon


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