RE: [CAD_CAM_EDM_DRO] Beginning User

Hi, Eric:

I haven't heard of a "CNC jr" (I'm not too experienced in this field
either), so could you explain exactly what you got?

Most of the hobby CNC G-Code interpreters do not provide cutter compensation
(G40->G42), so I'm not surprised that your's doesn't either.

A couple of suggestions -

1. Since autocad lite will generate a DXF file, you might want to consider
drawing an offset to your cutting lines equal to the radius of the cutter.
Let's say that you want to cut the outside edges of a one inch square using
a 1/4 inch diameter end mill. You'd draw the square using autocad lite and
then draw an offset 1/8 inch away from each of the lines. At the corners,
you'd draw a 90 degree ard with the corner of the square being the center of
the arc, and the radius being 1/8 inch. You would draw all of these offsets
on a separate layer (let's call it 'toolpaths') Export this drawing as a DXF
file.

Next, download a DXF to G-Code interpreter such as ACE Converter from Yeager
Automation. Open the DXF file that you just generated with ACE, select the
toolpaths layer, and direct ACE to generate the G-Code. Now, manually edit
the G-Code file that was just generated to add carriage feed rates, depth,
etc. If you're trying to cut a 1/2 inch deep cut, you'll want to copy and
paste the code that Yeager generates several times, changing the depth of
cut for each iteration (You don't want to cut the full 1/2 depth at once,
Depending on material you're cutting, you'll want to make a series of cuts
along the same path, but at different depths until you reach the full depth
of the cut. You may also want to cut a little "outside" of the lines as you
remove most of the material, and then take a full cut finishing cut that
removes little material, but provides a clean, uniform surface, but that's
another story)

This is your "low cost" solution. And, if you prefer a CAD program that
offers a little more power than ACLT, you might want to download a free
version of Intellicad, an Autocad workalike. Your net software cost is
zilch.

2. Since you're willing to spend some money on a program, you might want to
consider one of the CAD-GCode interprepeter generators such as VectorCADCAM.
The advantages of programs like Vector are that they often provide 'helps'
to the G-Code generation process. For example, the cut that I mentioned
before could have most of itsG-Code generated by drawing the offset (which
would also draw the radii around the corners) and clicking on a button.
You'd then enter the depth of cut in a dialog box, and Vector would generate
all of the iterations necessary to cut to full depth. Then, you'd add
another cut to finish it off (this may be automatable as well, Fred might
comment here) Since you know the autocad type programs, moving to something
like Vector would have an unlearning curve as well as a learning curve (I
started with the Intellicad-ACE combination and have moved over to Vector,
so I've gone through this curve), but it's well worth it, IMHO.

Now, as far as your G-Code interpreter is concerned. If your motors use a
step-direction interface with the computer, you can replace the G-Code
interpreter with one of several. Most are low cost ($20 -> $200) and run
under plain old DOS. A few run under Windows 9x. There's a WinXP beta out
for one. If you're willing to move to a Linux environment, there's EMC (I
was not willing to move to this environment, so I can't comment on its
capabilities)

In any event, I hope these comments provide some help and direction. You'll
find lots of folks more knowledgeable than me who are also willing to share
their experiences and insights.

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


|-----Original Message-----
|From: exeric1 [mailto:exeric1@...]
|Sent: Friday, July 05, 2002 10:42 PM
|To: CAD_CAM_EDM_DRO@yahoogroups.com
|Subject: [CAD_CAM_EDM_DRO] Beginning User
|
|
|Recently I purchased a CNC jr. I'm very happy with it for the most
|part but there doesn't seem to be very much native G code for it.
|There's no G code for tool diameter (radius) offset for example. It
|looks like I'll have to get a cam program sooner rather than later. I
|will be using AutoCad Lt for the design portion. I'm interested in
|suggestions for a cam program that will work well with such a
|restricted native G code. I don't need any design features in the cam
|program since I've already got CAD. Any info would be greatly
|appreciated. I really would rather not pay more than 600 or 700
|dollars.
|
|Another question I have is about using cutting fluids with CNC. The
|system I have that came as an option with the CNC jr seems like it
|puts out too much - It makes a mess of everything. Are there any good
|ways out there to manually control the flow. Also I would like to use
|a vacuum system for the metal chips that I already have set up for
|woodworking. What's a good method to get the chips without sucking up
|the cutting fluid? I've got a recirculating system for the cutting
|fluid and its too expensive to just get sucked away. Thanks in advance
|
|Eric
|
|
|
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