Please take a look over my shoulder – CAD CAM CNC Bench Mill System

I've been researching the web for three weeks to figure out how
to
select the software, electronics, motors, and mechanicals to put
together a bench mill system. You have all done this, so you have
very valuable experience pertaining to my hypothetical system. What
I am looking for is your opinion of the direction I am going in.
Please feel free to choose any part of the system to comment on. The
more detail the better. My objective is to select products that will
result in a system with no software / electronics interoperability
problems.
My application is to engrave (pointed cutting tool), and mill (end
mill cutting tool) both flat plates up to 4" by 4", and
around the
circumference of rings. I realize that I need to add a "4th
axis",
which will replace either the x or y axis. I am not sure which one. I
wish to machine brass, stainless steel, pewter, and plastic.
The "engraving" depth will be from 0.005" to 0.040".
As far as my capabilities, I am a hobbyist and have no CAD CAM CNC
experience. I am a competent machinist, and can operate application
software packages in the Windows environment. I really don't want
to
get into soldering, transformers, circuits etc. I am very fearful of
software / electronics interoperability, reliability, and
dependability problems.
My present system contains a MicroLux Milling Machine #82573
purchased from Micro Mark. I also have a MicroLux 7x14 Lathe #82710,
so I can do fabrication to mount servo motors, and or build new x,
and y axis slides. I'll start with the lead screws that came with
the
milling machine. Need information about, do I need to modify the lead
screw nuts, as an example. I plan to measure backlash.

Software
For CAD I am considering purchasing Rhino, and outputting .stl files
to the CAM software. I choose Rhino because all the jewelry
applications use Rhino. I'll be doing very simple
"jewelry"
machining / engraving. I am not a jeweler and do not intend to
become one. Also Tauseef of www.cuttingedgecnc.com stated that he
would definitely choose Rhino as his CAD software. Rhino can be
purchased from $600 to $900 roughly. If you are a student you can
purchase it for roughly $200 at www.journeyed.com, or www.data-
switch.net.
Now do I really need Rhino to do my application? I also want to do
the regular rectangular coordinate milling and drilling to maybe make
a bench top mill from scratch. I was surprised to see that many,
many people are doing just that. Do you know of other CAD software
that can do my application?
I found Virtual Sculptor
(www.minitech.com/software/virtualsculptor/virtualsculptor.htm),
VSCAM-01 at $2,600 discounted to $950. It seems to be both a CAD and
CAM package. The main module is CAM VS3D, and the auxiliary CAD
module Vscad3 is a traditional CAD program. This software does
engraving.

I guess I want to output .stl files from my CAD software. There is
also .dxf, but I don't understand why I would prefer .stl over
.dxf
output files.

For the CAM software I found StlWork2 a "low cost" 3D
solid/surface
tool path development system (www.aztec-
net.com/~jdemand/links.html). Price approximately StlWork plus
Accutrans, list $395 discounted to $75. Has anyone had any
experience with StlWork? The CAD output file must be .stl.
Again what would you suggest for the CAD and CAM software for my
application? Where do I specify the .stl mesh size? In the CAD or
the CAM software?

Next I guess I need translator software. The CAM output files are G
code, I think (what is M code?). I find the translator software
confusing. What is it doing? Is it part of the motor drive
electronics package, which provides the CNC signals to the motor
drivers?

I might want a tool-path simulation software.

Somewhere in all of this is the ability to set up the 0,0,0
coordinates to relate the cutter to the work-piece. Limit switches
to control run away programs, and something to turn on coolant. Also
something must isolate the PC from feed back from the motor driver
circuits and power supply. How do I do all this, and not touch a
soldering iron or read a schematic?

Again what would you suggest for each of these softwares to perform
these functions, and my application? I hate to admit it, but I
don't
have a clue of how the CAM software reads the CAD output file. Or
how the translator software reads the CAM output file. I realize
that I use a down scale PC to run the CNC software to drive the
motors. Again what is the CNC software? Is it the translator
software or is it the G code file?

Moving on to the motors, chopper drivers, and power supply. I have
my sights on LowCostCNCRetrofits (www.lowcostcncretrofits.com)
"INDUSTRIAL 5 Amp Servo System (Closed Loop) - Budget 5 amp Servo
Motion Control Package Deal 021".
3 Axis Small Milling Machine
**3 Axis Servo Motion controller with 2 internal opto relays**
**RAPID 24vdc / 150W Power Supply**
**Jog Pendant Remote (Ver.2)**
**3 / Hitachi 100oz.in Cont /500ppr. Servor Motors including pre-
wired leads**
Price approximately $1,399 US plus shipping. Has anyone purchased
their products? Are they in the US or off-shore? How is their
support? What happens if "it" stops running, and smoke comes
out of
the controller box?

I am also aware of IMService SYS-3-4axis complete, ready to bolt on
closed loop, servo CNC system with brushed DC servo motors, cables,
enclosure, and software. Price approximately $1,424.

Lastly I am aware of Dan Mauch, Camtronics-CNC.com products.
I'll
have to e-mail Dan and ask him what his servo system costs.
Dan's
site also contains very good information for the beginner. Don't
forget Tauseef of www.cuttingedgecnc.com, he has an unbelievable site
for the beginner.

Next the Mill and attaching the servo motors
Will the LowCostCNCRetrofits , Hitachi 100oz.in Cont /500ppr. Servor
Motors and chopper driver electronics (motor current and voltage)
have enough torque for my MicroLux Milling Machine acme lead screws
(#82573 purchased from Micro Mark)?
What will be the approximate maximum inches per minute feed rate,
cutting brass, with a 1/8" dia end mill, cutting 0.040" deep?
Should
I connect the servos directly to the lead screws (with flexible
couplings) or should I provide a timing belt reduction? What should
the reduction ratio be, and what is the technical reason for the
reduction and the ratio (other than more torque)? What do I tell the
CAM program about the servo motors, the reduction, and encoder
frequency? I'll be measuring the backlash in the acme lead
screws.
Should I replace the lead screw nuts? Do I loosen up the gibs on the
slides? Should I lap the ways? What else should I be doing?

There are pictures on the LowCostCNCRetrofits site of a customer
conversion of a bench mill that looks just like mine (SIEG of China
makes these bench mills and sells them to Micro Mark, Harbour
Freight, Grizley, Smithy etc for branding). The person implemented
timing belt reductions between the drive motors and lead screws. He
drove the large hand-wheel shaft which moves the z axis.

Well I wish to thank you in advance for any help or suggestions you
can provide. The more detail the better.

Whelen