CAD & CAM Software Whitepaper
Choosing the right design software to work with your PCNC can be confusing, especially if you're new these types of systems. There are lots of options out there – we even sell a few ourselves. Are some better than others? Undoubtedly. But determining which is right for you depends on a number of factors – the types of machining you want to do, your budget, your patience, etc. Below, we present a few thoughts to help you make an informed decision.
CNC Software 101
To understand CAD and CAM, it helps to understand the roles they play in the CNC process.
CNC mills like the Tormach PCNC 1100 use control software (in our case, Mach 3) to translate G-code into the machine motion that ultimately makes your machined part.
G-code is relatively simple to understand with a little bit of practice, and many times a few simple lines of G-code hand-typed in to the Control Software interface (called MDI, or manual data input) is enough to get a small job done.
The control software also comes with wizards – little programs that can help you easily generate code for more advanced movement like spirals right at the machine.
However, it will quickly become apparent that many machined parts – even those that look relatively simple – will in fact require 1000s of lines of code to machine. It would be an impractical, and not to mention error-prone task, to hand-code these parts. For this, CAD (Computer-Aided Design) and CAM (Computer-Aided Manufacturing) is the answer.
CAD is the tool you use to design your part. Whether you draft a simple line drawing or build a complex 3D solid model, CAD is where virtual pen is put to virtual paper and serves as the platform for animation, simulation, and in our case, CAM.
CAM generates machining tool-paths based on your instruction. For example: “cut this pocket with a ½” end mill,” or, “drill this hole with a 5/16 drill”. You tell it A) what to cut, B) what tool to use, and C) how to cut it, and it does the math for you.
CAM assembles a series of these commands into machining instructions, and then converts it all to G-code that the machine controller can understand with a postprocessor – basically a translator that allows the CAM program to speak to your specific machine in a meaningful way. Most CAM packages come pre-loaded with a library of post processors. Sometimes, you'll have to write your own, but almost all CAM programs have a utility to do this with.
Once you've got G-code on the controller, you're ready to cut – that is, after you've got your workholding, tooling and referencing figured out. But you're closer!
Choosing a CAD/CAM System
The
following are some suggestions for comparing
different CAD/CAM systems to help you
get started choosing which one is best
for you.
Ease of Use: Some CAD and CAM systems are easy to use. Some others, not so much. Almost all CAD/CAM companies offer free trial versions of the software to demo. Make sure to take them up on this. It's a great way to find out A) if the software can do what you want it to do, and B) if you'll still have any hair left after using it. And remember - while there are plenty of free demos, there are usually no refunds. Due diligence applies.
Support: Lots of CAD/CAM software companies sell an optional support and maintenance contract at additional pricing. Details differ between companies, but these contracts generally last one year and can be renewed for each year after. Most offer some form of individualized consultation and troubleshooting, exclusive members-only tutorials and content, and bug-patches or version upgrades for the life of the contract. It's worth pointing out that working machine shops almost always buy the support contract. If timely production is important to you, it's worth considering.
Audience: Different CAD/CAM
is marketed to different audiences and
may have unique features that make certain
tasks easier. Take a minute to learn
who the software is for. The same CAM
that works great for making manifolds
may not be the best choice for engraving
jewelry. Take a minute to do a few web
searches and find out what others in
your interest group use.
User Community: Most CAD/CAM companies now sponsor forums – message boards where their users can meet and discuss issues with the software. These can be an incredibly useful resource when learning new software as well as a place to discuss problems, software bugs, etc. Chances are good that you might already find an answer to your questions in the forum discussion archives. Websites like www.cnczone.com also have independently run forums on many of the popular CAD/CAM software. We highly recommend visiting some of the forums before making a major software purchase as well as continuing to use them as a troubleshooting resource.
Online Resources: Some companies have free training videos, tutorials, etc. published online. Some require an optional membership to access these resources. Most fall somewhere in-between, with a combination of free and exclusive content.
Extras: Many CAD programs will have part libraries that have premade models of common components like screws, nuts, bolts, etc. These can be helpful if you plan to do mechanical design. They may not be that useful if you are only using CAD to design parts for your CAM. Others offer different modules or plug-ins – Sheet metal design, Finite Element Analysis, Graphic Renderer, etc. While a lot of this isn't helpful for CNC work, it might be valuable to you if plan to use your system for more than just machining. Many CAD/CAM systems offer different levels of the same system – basic, professional, expert, etc. Understand what the differences are between the levels. You may not need all the options and extras. A lot of systems also let you pick and choose options or plug-ins.
Education Discounts: Are you an educator? You're in luck. Lots of CAD/CAM companies offer education versions of the software at significant discounts. It's a great way to get top quality software for your HS shop class or Robotics team.
Price: The old adage, “You get what you pay for,” generally holds true, but there are exceptions. You'll be able to sniff these out pretty quickly by visiting some of the independent internet forums like www.cnczone.com. Finally…also realize that for every top –end software, there is a more budget-friendly competitor that may make more sense for hobby or small-business. While everyone would love to have state-of-the-art software, the cost of ownership can be prohibitive and the complexity and scope of features can take a long time to master.
More on CAD
CAD is ubiquitous in the design world today. Long gone are the days of AutoCAD being the sole choice for PCs. There are now lots of affordable options available that are more powerful than state-of-the-art systems from just a few years back. All of these can do 2D drafting, most can do some 3D modeling, and quite a few can produce very complex 3D models and assemblies.
There are 2 types of CAD technology in wide use today:
Parametric CAD: A Parametric CAD program is most often the first choice for serious mechanical design. This is what working machine shops use. It‟s a concept that can be hard to explain, but once you understand it, it seems like common sense.
Say, for example, that you're designing
a part with a pattern of bolt holes.
Consider
one hole, and you'll find it
is defined geometrically with a set
of parameters - diameter, depth,
thread depth, thread pitch, etc. With
parametric CAD, you can easily make
a change to a parameter and your model
will update to reflect the change. And
parametric CAD can also recognize all
the holes in the pattern are the really
the same feature and update them all
at the same time. It recognizes design
intent, and this makes it very effective
when designing families of parts or
when doing quick modifications or design
edits. Examples: Alibre Design, Solid
Edge, Solidworks, CATIA, Pro/ENGINEER,
many others.
Free-Form 3D CAD: If you plan to design art, jewelry, etc., a CAD program with advanced Free-Form design options might be more appropriate. You'll be able to produce complex organic surfaces, although you'll probably sacrifice some of ease-of-use and speed that makes a parametric system so good at mechanical part design. Examples: Rhino, Autodesk Maya.
There are also loads of other “basic” CAD programs available. These aren't going to have many of the advanced modeling features that professional software have, but you'll still be able to do quite a bit. Just make sure adjust your ambitions accordingly. Examples: TurboCAD, AutoSketch many others. When choosing a CAD system, keep in mind what your design goals are. There are lots of options out there if you only plan to use CAD occasionally for simple design work. More serious mechanical design will benefit greatly from a Parametric CAD program, and a 3D free-form modeler might be the best choice for aesthetic-driven design. Take a minute to see what others in your area of interest are using – a couple quick internet searches should really help to narrow down the field.
More on CAM
As far as the CNC user is concerned, the differences between CAM systems are much more significant. Not every CAM system can generate commands for every type of machine movement. Make sure you understand A) what your machine is capable of and B) what is possible of the CAM system.
2D CAM can command X and Y moves. It cannot command Z movement. The machine operator manually sets Z position. While you can still find specialized 2D CAM available, nowadays most general purpose CAM is at least 2.5D. Uses are routing, plate cutting, and engraving.
2.5D CAM can command X and Y moves.
It can command Z moves, but not at the
same time (simultaneously). It's suitable
for producing terraced parts. Most 2.5D
CAM can also do drilling. Uses are Fixtures
and Jigs, Simple structural components,
and Facemilling.
3D CAM can command X, Y, and Z movement simultaneously. It's capable of producing contoured surfaces. Uses are Complex 3D surface contouring, Mold making.
However…Not all 3D CAM is created equal.
4th Axis: Some 3D CAM doesn't support 4th Axis motion. Some 3D CAM only supports 4th Axis indexing – that is the 4th axis cannot move simultaneously with XYZ movement. Simultaneous 4th axis movement can command rotation on the turntable at the same time as XYZ movement.
Lathe: Not all CAM can do Lathe programming. If you plan to do CNC lathe work, make sure your CAM has a lathe module. Sometimes this is included. More often, it is sold as an upgrade option. There are also standalone CAM packages for lathe.
If your goal is 4th-axis or lathe work, make sure your CAM is up to the task.
So what really sets the CAM competition apart?
Integrated CAD/CAM: Integrated CAD/CAM functionality makes it easy to move between design and manufacturing design. There is no need to import and export .IGES, .STP, or other industry standard formats from CAD to CAM. The advantages are increased productivity and a one-stop spot for software support. The disadvantage is it forces you to commit to one provider for all your software.
Integrated CAD/CAM makes a lot of sense if you plan to do both design and manufacture – prototyping, fixture design, etc. It makes it easy to move back and forth between CAD and CAM as you implement design changes. You won't need to start from anew in CAM for every minor design tweak.
So why not consider Integrated CAD/CAM? For one, they tend to offer less CAM functionality than a dedicated CAM package at the same price. If you plan to do less design work or choose only to work with stable designs, you'll get more for your money with dedicated CAM.
Machining Strategies: One key way that CAM packages differentiate themselves is by the number and complexity of the machining methods included. A simple CAM program may offer only a few methods, Roughing and Finishing, for example. More sophisticated CAM programs have much larger libraries. AlibreCAM, for example has a variety of machining strategies available depending which level you purchase (Standard. Professional, or Expert).
A Brief Word on Postprocessors
A postprocessor is the 'translator' that converts the language of your CAM software to G-code that your CNC machine can understand. CAM systems will often come preloaded with a library of postprocessors for common CNC machines. If your CAM doesn't have the postprocessor that you need, you will either need to create it or find a suitable substitute.
The Tormach PCNC 1100 will work with many generic 3-axis vertical mill postprocessors. For 4th axis support, it's likely you will need a postprocessor specific to the PCNC 1100. The Duality Lathe will work on many generic Lathe XY post processors. However - always verify an untested postprocessor for function before trusting it with expensive tooling or workpieces. Run your program in air before you cut to make sure it behaves like it should and debug if necessary.
A postprocessor for the PCNC 1100 is included in many popular CAM packages. For CAM systems that don't have a preloaded PCNC 1100 postprocessor, check the internet. Somebody may have already created one they are willing to share. Otherwise, you'll need to make your own – most CAM will come with a utility that allows you to do this.
For information on G-code commands understood by the PCNC Control Software, refer to Chapter 7 of the Users' manual. You'll need this information if you need to create your own postprocessor.
Tormach’s Software Offerings
We are a reseller of several CAD/CAM systems that we feel are an exceptional value in the marketplace. In some cases, we've negotiated special reduced pricing for software when purchased for use with a new or existing PCNC.
SheetCAM: SheetCAM is a very affordable 2.5D CAM. It can program profiling, pocketing, and drilling operations. It has no CAD capabilities; you must import .DXF 2D drawing from CAD.
Why do we like it? First, it's cheap – less than $200 for a fully functional version. And it's about as simple to use as it gets. If you have zero experience with CAM, this is great place to get started without getting in over your head. But…It doesn't do lathe. It doesn't do 3-axis contouring. This isn't the software to use if you want to make complex 3D parts.
Check out the user forums at:
http://tech.groups.yahoo.com/group/sheetcam/
http://www.cnczone.com/forums/forumdisplay.php?f=262
TurboCAD PRO with optional CAM plug-in: TurboCAD Pro is 2D drafting/ 3D modeling software. If you've ever played around with early AutoCAD versions, you'll see a lot of similarities.
The CAM plug-in offers integrated 2.5D CAM, which makes for easy design changes. It has a lot more functionality than SheetCAM: Pocketing, Drilling, Tapping, Roughing, Engraving, Boring, and more. It also comes standard with a Lathe module.
Why do we like it? TurboCAD really shines for 2D drafting. It will do everything you need it to do for 2.5D CAM work, and its capable of some 3D design as well. It's also a very budget-friendly choice for Lathe CAM.
But…It doesn't have a lot of the 3D design tools available with parametric software. Its fine for 2.5D parts, but it will probably underwhelm you for serious mechanical design.
Check out the user forums at:
http://www.cnczone.com/forums/forumdisplay.php?f=83
Alibre: Alibre offers CAD at 3 different price levels – Design Standard, Design Professional, and Design Expert. You can think of these as the same CAD software with different add-ons. Alibre CAM plug-in is included with Alibre Design Expert and is basic 2.5D and 3D integrated CAM.
Why do we like it? Alibre is closest to the look, feel and functionality of the premium CAD packages that engineers and designers are using today, but at a very friendly price. While it might not be the solution for a large design team sharing files and design work around the world on a constant basis, it certainly fits the bill for many small shops, entrepreneurs, and hobbyists.
But…The CAM plug-in included with Alibre Design Expert is bare-bones basic. And it's strictly 3-axis – it doesn't do any 4th-axis, indexing or continuous, and it doesn't do lathe. However, be aware that Alibre also offers three other levels of CAM - Standard ($1000), Professional ($2000) and Expert ($4000) - that add 4th and even 5th axis functionality. All are plug-ins that require Alibre Design CAD.
Check out the user forums at:
http://www.cnczone.com/forums/forumdisplay.php?f=83
SprutCAM Master: SprutCAM Master is a standalone CAM package with built-in lathe module and continuous 4th-axis support. SprutCAM offers several levels (Machinist, Universal, Expert, and Master), but Tormach only offers SprutCAM Master, which is the highest level.
Why do we like it? Hands down, it's the most powerful CAM package available for the price. It's capable of continuous 4th-axis motion and also has an included lathe package. No integrated CAD, but 2D drawing tools to incorporate fixturing, etc.
But…Rock bottom pricing doesn't come without sacrifice. The learning curve is challenging with SprutCAM. Free online tutorials and instruction are sparse. Online documentation can be confusing and difficult to understand. And those pesky bugs! Be prepared to spend a fair amount of time surfing the forums until it “clicks” for you.
But don't despair; there are options to help with SprutCAM. There are subscription support services available that are very good and very affordable. SprutCAM with a 1-year support contract is still less money than many less powerful CAM systems around. You'll be wise to consider investing in one if you don't have plenty of time and patience.
Check out the user forums at:
http://forums.sprutcam.com/forums/
http://www.cnczone.com/forums/forumdisplay.php?f=156
http://www.youtube.com/results?search_type=&search_query=sprutcam&aq=f
Last Updated 4/8/2009
Download the CAD & CAM Whitepaper (PDF)