Paul,
The typical workflow is to first design the part in a CAD program then, use the output of the CAD program as input to a CAM program to generate what is called G-code. The G-Code is then loaded into the software on the mill. The software on the mill (often times, people use a program called Mach 3) then controls the mill to make the part.
Learning a CAD program takes a little time and practice. There are some free share-ware programs but many do not have the feature to export the file for use by a CAM program. Also, the free share-ware programs have the usual problem of not being supported and often are not very mature and have too many bugs. CAD programs which have CNC file output capability can be expensive ranging from $1000 to $6000 with maintenance fees running between $300 to $1000 per year. I happen to use and like a program called Geomagic/Alibre. It is full scale, professional stuff and is at the lower end of the mentioned price ranges. There are others but, when selecting a CAD program, you need to stick with a company that will be in business for a while as, it takes between 6 months to a year to become proficient with any particular package. Other packages out there are TurboCad, RhinoCad, Solidworks, AutoCad... There are others but these are the more common ones that have a reputation and arent' going away anytime soon.
CAM: CAM programs generate a computer image of the part and machine and provide ways for you to set the tooling types, paths, speeds, ranges of motion etc. More often than not, they let you simulate the motions and preview all actions thus allowing you to minimize crashes. Likewise, they too have a learning curve and typically cost as much or slightly more than CAD programs. The more common packages are VisualMill (Mecsoft), SprutCam, BobCam and CamBam.
There are some CAM programs that "plugin" to your CAM program and the two software packages work from the same familiar working environment. For example VisualMill has a plugin for Alibre/Geomagic and all the screens work the same way as the ALibre CAD program.
The controller software -most commonly is Mach 3 and it allows you to (among other things) stop/start the machine in between sequences. Mach 3 is pretty inexpensive at about $300.
Right now, I'm in the market for a CAM program and I've selected the 4 axis version of VisualMill. Since I'm a licensed user with current maintenance on Alibre, the VisualMill software is $2500. It would otherwise cost a little more but the two companies have a partnership.
It just so happens, I like Geomagic/Alibre but, I'm also getting familiar with Solidworks; thus, I can only render opinions about those two programs. Be apprised, Swx is $6000 for the simplest package and it goes upward from there. I also played around with a demo version of TurboCad and found it very difficult to use. -Everyone is different about their preferences...
Of course, you could bypass all this and simply write G-code to control the mill directly. I wouldn't advise this anymore than I'd advise a person to write computer code in machine language or assembly language. -Just so happens, I still do a lot of machine and assembly language programming -and it is very, very time consuming...
Ray
EDIT: Most of the CAM programs mentioned above fall in the "Advanced Hobbyist and Low-End Professional" category. Those programs are designed for use on general purpose mills and lathes. There is a whole additional category of "High-End, Professional" software out there but the prices range in the 7 to 10 grand (and much higher) category.
Also, there might be cheaper ways to get into this but, I did not research them as, I'm mainly looking for professional-grade packages with name recognition that can be used on a resume and used in a professional setting.
Hi
Looking to CNC my mill or Buy one , question is what programs are the easiest and cheapest to design the part and then just send it to machine ? or are there steps in between ? if someone can give me and idea of the work flow from design to a finish part, I'm very "green" in the CNC subject, will probably take some courses in CAD design programs but it seems there are are bunch of them now on the market would like some opinion on this
Thanks
Paul.W