RE: [CAD_CAM_EDM_DRO] Re: Hi I'm new

The product that you're considering does not have an 'on board' rate
generator. It simply acts as a power amplifier (and possibly an isolator)
for the current that the printer port can provide. This item can (and
probably does) work, but I'd look at something like the Xylotek (I believe
that's the correct spelling) instead.

Typically, a CNC system works as follows:

1. You draw the part using a CAD program.
2. You use a CAM program to convert the CAD drawing into a series of
commands, called G-Code, that a CNC controller program can execute.
3. You use a G-Code interpreter to actually generate the signals that are
sent to the printer port (or to some other port depending on the
hardware/software that you have) Most of the G-Code interpreters in the
'hobby' world will sent the correct signals to a printer port to control a
'step and direction' motor driver. A few of these G-Code interpreters will
drive phase motor drivers, and a few will drive servo motors.
3a. Some G-Code interpreters require that a separate rate generator be
inserted between the printer port and the motor drivers. Usually, this
driver provides the robust pulse train from a Windows based G-Code
interpreter so that a software driver is not required. Other times, the rate
generator is used as a means of 'protecting' the software from piracy (the
software won't drive the motors without the hardware box).
4. Next, you have power drivers that actually drive the motors. And, you'll
also need a power supply.
5. Currently, most of the hobby oriented G-Code interpreters run under DOS.
One runs under Linux, and a few run under Windows. The trend is towards
Windows, but I think that DOS will be with us for a while.

I'd suggest you use the following:

1. Intellicad 2000 as your CAD program - it's free (legally). Use it to draw
your parts and generate a DXF file.
2. Yeager Automation's ACE Converter - it's also free (legally). Use this
program to convert the DXF files you've generated into G-Code. Note that
you'll have edit the file produced by ACE to compensate for the cutter
diameters and also set up any pockets manually.
3. Start with a DOS G-Code interpreter. I use TurboCNC (I should mention
that I have an interest in this program) but there are others. TurboCNC is
shareware. The program that you download is complete, not time limited, and
does everything that the 'registered' version does. The shareware fee gets
you the source code, written in TurboPascal, so you can modify it if you
desire. Later, if you want a windows based system, you will be replacing the
DOS based G-Code interpreter, which is a low cost investment.
4. Use the Xylotek driver boards. They cost around $100 for three axes,
fully assembled. ther alternatives are Gecko drives or Dan Mauch's drive
kit. I used Mauch's kit; if I were starting today, I'd strongly consider the
xylotek board instead.
5. Build your own power supply
6. Use Sherline's coupling kit; it's a cleanly designed system that works
well with either the Shreline mill or lathe (there are different kits for
each of the models it sells)
7. Use double ended motors so you can use the handwheels along with the
motors. I chose Sherline's motors simply because they were double ended. You
can find cheaper ones if you look. Sherlines are 100 oz-in, which does a
decent job with their products. Others will say that you don't need the
handwheels once you've got CNC. Personally, I've found them to be useful.

Hope this helps.

-- Jerry

If you purchase a step/direction controller, you'll have the most versatile
hardware system.

|Thanks for answering, that makes sense to me. If I understand this
|correctly, rather then trying to generate pulses directly from my
|parallel port, I could buy a controller such as one of these:
|
|http://steppercontrol.com/controllers.html
|
|and that would generate those pulses for me? Their website isn't
|exactly clear but I get the impression that my computer would tell
|the controller what it wants (to rotate the motor by x amount), and
|the controller would generate the pulses to make it happen. Am I
|getting it? I thought I understood the driver/controller
|relationship, but now I'm a little confused.