RE: [CAD_CAM_EDM_DRO] Introduction & request for help

Weyland:

I'm in the process of converting a Sherline mill over to CNC. Here's what
I've figured out. It should also match your plasma cutter.

First, of course, you need a stepper motor for each axis that you want to
control.
Next, you need some way of mounting the motors on each axis and coupling the
motor shaft to the leadscrew of that shaft.
You'll also need a driver for each motor. This is an electronic circuit tha
converts the "step and direction" information coming from your computer
motor into the appropriate sequential current pulses to move the motors. If
you're into kit building, you can buy one of a couple of drivers that
Camtronics sells. These kits are easy to build (I'm in the process of doing
that now), but require some know-how and willingness to buy the "extra"
items, such as power supply, switches, fuses, cabinet, etc. that a complete
system requires. Camtronic's kits handle three axes, plus something like a
fifty dollar bill gets you a fourth axis) If you're not into kits, then you
can buy something like a Gecko driver. I have no experience with these
drives, but people on this list seem to think that they're guite good. The
guy who designs them is active on the board and provides quite a bit of
support, both for his own units and for providing general information. With
the Geckos, you'll still have to complete the package (power supply,
switches, etc.) but won't have to assemble any circuit boards. Gecko drives
supply one motor each, so you'll need three of them.

After that, you'll need a parallel port on your computer (printer port will
do) and a 25 pin printer cable (with all 25 pins connected) to go between
the computer and the driver.

If you want to add limit and home switches, you'll also need them. These
would be connected to the driver boards, not to the computer.

Your third alternative here is to purchase a packaged "retro" system that
has all of the goodies prepackaged and you simply mount the motors and
install the cables between. This route is probably 25% to 50% higher than
the cost of piecing everything together. I'll know for sure once I get mine
to make chips.

That would take care of the hardware.

Then, there's software. When you're running a part, you'll need a G-Code
interpreter to convert commands from the computer into a series of step and
direction pulses and levels in the correct timing. These can either be
purchased, or had for free. TurboCNC is the freebie while most of the others
cost anywhere between $20 and out of sight, with $100-$200 being the typical
price. I'd like to comment further, but not having used any of these
programs other than to plot something on the CRT screen leaves me walking on
thinner ice than I am comfortable doing.

Now that you have a system that can accept G-Code programs and convert them
into a part, you need some way to generate the programs.

One way is to do everything yourself. If that's the case, a simple text
editor (Notepad for windows, for example) is all that you need. That, plus a
good knowledge of G-Code programming. Or, you can purchase a system that
allows you to draw the part in a CAD program and let the program convert
everything into G-Codes as necessary. You can use either a fully integrated
program such as VectorCAD, or get a no-cost Autocad workalike such as
Intellicad-2001 (From Atlas or CMS, the web sites have been posted in the
past few days) and use a DXF file to G-Code converter to get your G-Code.
Yeager Automation offers ACE Converter for free. They also make a DOS based
G-Code interpreter that some folks here seem to like.

I think that I've covered all of the items that you need. Sorry that I can't
be specific on capability and robustness of any of the items other than tell
you what I've purchased, but I know only enough to be dangerous enough to
thin out my wallet. Right now, I'm happy with the quality of the boards that
Camtronics produces.

-- Jerry Jankura
Strongsville, Ohio
So many toys, so little time


| -----Original Message-----
| From: Weyland [mailto:weyland@...]
| Sent: Saturday, July 21, 2001 9:07 PM
| To: CAD_CAM_EDM_DRO@yahoogroups.com
| Subject: [CAD_CAM_EDM_DRO] Introduction & request for help
|
|
| Greetings~!
|
| My name is Weyland Smith.
| I subscribed at the recommendation of one of your other members.
| I am very interested in learning more about building CNC's,
| but am finding it difficult to sort out the information I've found so far.
| Hopefully you can help me decipher some of it.
|
| I want to build a CNC plasma cutter
| and if it goes well, I'll convert my mill.
| The construction part of it is of little concern to me as I'm
| a tool & die maker, and have my own machines I can use to do this.
| I also build computers on the side, and so have
| access to many parts for that aspect as well.
|
| My problem is this -
| I want to use a PC to control the stepper motors
| I've planned to use for the project, but am very unclear
| on what exactly I need.
|
| I've surfed and surfed, read many a page, and just can't seem to get
| my simple mind around this part.
| As with many I've read about in my searches, economy is an issue.
| I don't have much money, but do have time and a willingness to learn.
|
| Once the structure of the machine is built, and the
| motors attached, what exactly do I need to make it run from a PC?
| Once I write the code, how do I get it to run on the machine?
|
| I've seen and collected many of the programs out there,
| but really don't know *which* I'm supposed to use, due to my ignorance.
|
| Any help you can give or direct me to is greatly appreciated.
|
| Thanks,
|
| Weyland
|
|
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