CNC Mill & Lathe Learning Curve
Needed Steps to Take Before You Buy
CNC Equipment
By Jay Steele
Lafayette, IN

Using a computer controlled lathe and mill to produce identical parts may sound like an easy way to get a job done, but, whether you buy a complete package, or build your own system, you'll have a lot to learn before you can even get started.

I hope this review/tutorial will help you overcome some of the pitfalls, misconceptions, and screw-up's I made during my search and purchase of the perfect CNC System for my needs.

STEP 1) Determine your needs:

              What do you want to make? 
              Are you making molds?
              Are you machining parts?
              What level of accuracy is needed?
              What material are you going to use?
              How big are the items you want to make?
              How fast do you need them produced?
              Do you need to produce 2D, 2.5D, and 3D parts?
              How many axis will your designs require?
              What is your budget?
              Where can you get help?
              What tool do what job?
              What accessories do you need?
              Etc.

Using myself as an example, I'll answer these questions:

I plan on using the lathe to make miniature parts for furniture.  Some of these mini parts will be made from metal, while most will be made from wood.   The mill will be used to make molds for casting parts that can't be cut on a mill or lathe easily.  It will also be used for precision hole drilling, as well as 2.5D and 3D parts carving.  All of these parts will be small, under 6" for the mill and under 15" for the lathe, so there's no need for a full size mill or lathe.

The majority of my work is done in wood, but I'll also need to use plastic, steel, copper, brass and aluminum on occasion.  Production of these items needn't be extremely fast, but not too slow either.  I need at least 4 different axis' as well, but may need to increase that at a later time.

My budget is limited, so I need to make sure I can afford everything I need before I start spending the money.  Just a note here - want and need are exclusive of each other - If I got everything I wanted, I would be in debt for years to come, getting what I need will get the job done, and I won't have to worry about next months rent.

Help can be found in may places on the Internet, chat rooms, forums and the sites where you get your equipment and software.  Some sources are better than others, but you'll have to figure out which ones are best for your needs.  Forums provide a lot of information from some of the best machinists in the world - Just make sure you use the forum's search function before you ask a question, as most of the time your question has already been answered.  Click Here for a Few Places to check out. 

Step 2) Choosing the Right Software:

What may surprise you is the software to run your CNC systems can be more expensive than the CNC machines.  The more expensive the software, often, the easier the CNC job becomes.  Free or cheap software (with a few exceptions) means the more you'll need to know before you can get started.  The more you're willing to do manually, the more you can save when it comes to buying the needed software.  You'll need to:

             Learn what steps are needed to go from design to the CNC equipment.
             Learn which tools are needed to build what you want, and their cost.
             Download and learn trial versions of the software you like.
             Get a simulators to practice with - before you cut.
             Search for tutorials online to help you learn or take a class.

Using myself as an example, I'll answer these questions:

If you have experience with G-Code - you can always just write the code needed to produce a part in any simple text program - Me being totally unfamiliar with G-Code will have to do it the way I describe below.  I also want to actually see the item before I produce it, and the 3D software helps.

There are several steps to produce a product with CNC equipment, the first is to produce a model (drawing) of what you want to build, and the best way to do that is to use a 2D-3D software package designed to save the file in a format that can be converted into G-Code.  3DPlus 2, AutoCad, SolidWorks, Corel, OneCNC, BobCad, CadSoft, just to name a few, each have their benefits and downfalls and vary in price from nothing to thousands per package.  Most have trial versions you may download and use for 30-90 days with most functions intact.  I advise asking the price before you try, as you might get spoiled and not want anything else, only to find out you can't afford the packages you want.  Click Here to do a Search. 

After you have mastered the fundamentals of model drawing, its time to move onto converting you're drawing into G-Code so your CNC machines can make the part you want.  G-Code is ALMOST a universal code, while most CNC software & machines can understand most of it -- some have limitations, and the G-Code exceptions you'll need to know before you try using on the machine of your choice - otherwise you might damage the machine or the tool you're using, also ruining the piece you're working on.

There are dozens of software packages out there that will convert the properly saved file into G-Code.  The most common files that are convertible are cad files with the extension of .dxf, .stl, .hgpl, others may require an additional procedures to convert to a usable file, requiring additional steps and possibly another software package.  Click Here to do a Search.   

Before I do any cutting, I test the G-Code in a CNC simulator.  Testing to make sure the G-Code is cutting the pattern I planed, as well as checking the cutting speed, depth of cut, feed rate, needed cutting tools, etc., all to make sure I don't do more damage than good.  Getting a simulator is easy, just Search the Internet and decide what you're willing to pay.  NOTE! some of the G-Code conversion packages come with CNC simulators.  Be very selective on this software, as the CNC simulator has to work with the software for the equipment you're planning to buy!

Once your file is converted into G-Code it can be put into yet another program to communicate with the CNC machines.  Choosing the best software package here will require you to once again determine your needs - use the Internet to search for these packages and download the trial versions to find the best ones to do your job, and are compatible with the hardware you're going to buy.

Step 3) Buying the right machine.

You're answers in step 1) will help in determining which CNC machine will meet your needs.  This is no easy task, as there are dozens of different machines to choose from, and without experience the choice is even more difficult - if not completely thought out you can make a very expensive mistake.  Forums help here quite a bit, as there is at least one forum for every type of machine out there, and you'll generally find both pros and cons for each machine in their forums.

CNC equipment is not cheap, starting around $2,000.00 -- $50,000.00 and even more for the most elaborate units.  So careful planning is very important, and should help in preventing those costly mistakes.  Begin your search on the Internet and find both equipment and forums to browse and ask questions.  Before long, you will have some idea as to what you need.

The required bits and accessories for doing the job you plan also come at a price, so care must be given when choosing the right tools for your jobs as well.  There are a lot of aids on the Internet to help you determine what does what, at what speed and feed rate, etc., so gather this information as you search, and keep it handy for when you start using your CNC equipment, it becomes your best chance to do the job right, the first time.

Step 4) Making the Purchases:

The time to commit and choose a machine is now at hand, no one can make this choice for you, as it is your needs that have to be meet!  Buy what you need, don't skimp, as this will make it nearly impossible to do what you need to do, and could end up frustrating you and become a big waste of money.  Think, re-think and think once more before you make the purchase.  And while you're waiting for the equipment to arrive - practice with the software you've decided will work best for your chosen equipment, and prepare to dazzle the world with what you'll make.

Good Luck