What’s a CNC Simulator and How Can They Help?

CNC Simulators follow in the footsteps of many other kinds of simulation.  Ever since computers became available, simulation became a powerful or even the preferred way of solving problems.  The idea is to model the math behind whatever the problem is on the computer.  That math, if the problem is well enough understood, will predict what will happen when various parameters are entered as inputs.

What’s the difference between having a formula that simply gives the answer and a simulator?  Having a straight up formula is faster and easier, but often formulas don’t exist to give the answer.  In addition, for something like a g-code simulator, the answer isn’t a single number.  As a result Simulators can solve an extremely broad range of problems.

The goal of a CNC Simulator (or any other Simulator), is to solve the problems faster and easier than fooling around creating the real thing and using trial and error.

G-Code Simulators

cnc simulator

G-Wizard Editor is a G-Code Simulator…

One of the most common and useful types of CNC Simulator is a G-Code Simulator.  We even make one ourselves–G-Wizard Editor is a G-Code Simulator.

The idea behind a g-code simulator is to eliminate manual testing of g-code part programs by using a simulator.  With a good simulator, “cutting air” should not be a requirement before you can run a part on a CNC Machine.

This kind of CNC Simulator can save a lot of time for the CNC Programmer, and also eliminate the need to tie up an expensive CNC Machine for testing.

Here’s a video on G-Code Simulators:


CAM Toolpath Simulators

Another type of CNC Simulator is the CAM Toolpath Simulator.  They’re included with almost every CAM software package.  They use 3D graphics and show the progress of the tool whittling away material to create a finished part.

Visually, CAM Toolpath Simulation is very satisfying.  But they have their limitations as a type of CNC Simulator.

The problem is they work off the geometry model the CAM software uses to create toolpaths.  This is in contrast to a g-code simulator that works from the g-code your CNC Machine will actually execute.  Remember, it doesn’t see the CAM package’s geometry model.

If there are any problems with the geometry model, any bugs for example, the CAM Simulation may look perfect only to have the part crash on the CNC Machine.


That CNC Simulator did not do its job if that can happen.  Shops that want to go from programming office directly to running parts prefer G-Code Simulators.  Sure, they also use CAM Toolpath Simulators, but only to visualize what’s happening and as a first check.

Feeds and Speeds

cnc simulator feeds speeds

G-Wizard Calculator is a Feeds and Speeds CNC Simulator…

It seems odd to think about Feeds and Speeds “Simulators” when we are used to calling them “Feeds and Speeds Calculators”.  But in fact, they are truly CNC Simulators if they do everything a true top-of-the-line Feeds and Speeds Calculator can do.

Consider these CNC Simulator functions in G-Wizard Calculator:

  • CADCAM Wizards will run hundreds of simulation scenarios to find the optimal combination of Cut Width and Cut Depth to maximize Material Removal Rates and reduce cycle time.
  • The Feeds & Speeds Engine considers about 60 variables before recommending Spindle Speed and Feedrate.
  • The behavior of dozens of different Tool Types has to be accounted for.  Everything from Endmills to Turning Tools to Saws so G-Wizard can give Feeds and Speeds for all the many types of tooling used in CNC.
  • The CNC Machine’s capabilities must be accurately simulated as well.  G-Wizard simulates not just basic specs like rpm range, spindle power, and maximum feedrates.  It also simulates spindle power curves, rigidity compensation for lightweight Hobby CNC Machines, and more.

Those are just a few examples of how G-Wizard goes well beyond being a basic “Calculator” and is a full-fledge Feeds and Speeds simulator.  You could never calculate everything it does in a spreadsheet, for example.

That’s why it is so much more powerful as a tool to improve your Feeds and Speeds while making your work less.

Quote Estimators

cnc simulator quote estimator

G-Wizard Estimator is a Feature-Based CNC Job Simulator

The work needed to estimate the cost of machining for a Job Quote is a perfect example of a great CNC Simulator.  At least it is when done correctly.

A lot of estimation software out there tries to just apply fudge factors to real numbers gotten from similar parts.  That’s not true simulation, and it doesn’t produce accurate results.

Don’t believe me?  We surveyed CNC’ers about Job Cost Estimation and I was shocked at the results:

  • It showed that nobody was happy with their existing solution.  We do a lot of surveys and this marks the first time everyone was unhappy!
  • The biggest complaint was that the software was inaccurate.  This is what I’m saying about not using simulation-based solutions for estimating.  I like to use the word “Feature Based Estimation” to mean that every feature you’ll machine on the part needs to be addressed in the estimate.
  • The second biggest complaint was the amount of effort required to create an estimate.

Imagine that.  Software that requires an incredible amount of effort to produce a wildy inaccurate answer.  It’s no wonder everyone is so unhappy.

Now contrast that to something like G-Wizard Estimator:

  • It simulates each feature to be machined.
  • It used the same Feeds and Speeds that will be used to do the job because it is integrated with G-Wizard Calculator.  This is a huge gap for most other estimators.
  • It also simulates non-machining operations such as the need to flip a part over for a 2nd op or the time and cost to have a part bead blasted or anodized.  It even covers inspection.

That’s what it takes to generate accurate quotes, yet GW Estimator also makes those quotes easy by streamlining the input parameters.

CNC Control Simulators

CNC Control Simulators are another class of CNC Simulator.  Check out these table-top Haas simulators:

cnc simulator haas control

Aren’t they cool?

This type of CNC Simulator is mostly used for education.  They’ll help the operator learn how to run the control without tying up an actual CNC Machine.


A good CNC Simulator can save a lot of time.  There are a number of different types available.  Isn’t it about time you took advantage of whichever ones make sense for your work?


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