2 weeks by cncdivi


Is G-Wizard best for Big or Small CNC Machines?

Is the G-Wizard Calculator more suitable for generating optimized feeds and speeds for large-scale industrial machines, or smaller hobby machines? In reality, it has distinct features designed to cater to both types of users.

I was recently contacted by a G-Wizard user who was unhappy that some folks on a forum thread felt our G-Wizard Calculator was only good for Big Industrial Machines and not so much for little routers.  I told him I also hear sometimes from Big Industrial Machine people who think it can only be for the little machines.  Who is right?

As I write this post, almost 60,000 people have used G-Wizard.  Not everyone buys it, but many do.  I regularly hear some pretty amazing things back from our audience that range from, “G-Wizard saved us $20,000 in machining cost during the trial period,” to, “Finally, I am making serious progress with my small CNC machine.”  

Clearly, the first is a Big Industrial Machine person and the latter is a Hobbyist.  

Tormach recently named us one of the 10 CNC things they’re thankful for.  They’re a wonderful brand that falls somewhere in the middle.  I like to call them “Prosumer” because you can certainly use Tormachs for business or pleasure.  I know of plenty of people who’re making their livings with one and plenty who are having a ball making whatever they want to with a Tormach.  But, we have manufacturers who make much higher end machines that recommend us to their customers too.

The truth is, G-Wizard can be invaluable to either audience, but getting the most benefit from it requires familiarity with some of the features designed to help one audience or the other.  Put another way, the amount of benefit you get from G-Wizard is a function of how much information you can give it about what you’re doing.  The more information you’re willing to give, the more of G-Wizard’s special features you’ll want to call on to get even more value.  Let’s see how that works.

G-Wizard Straight Out of the Box

The more data you give G-Wizard, the more it can do for you.  But let’s start out assuming you’re just going to configure a basic machine profile and go.  What do you get that’s special?

Quite a lot as it turns out.  You’re going to get Very Good Feeds and Speeds Calculations.  Here are some of the things that go into Very Good Feeds and Speeds:

  • Adjust your Feeds and Speeds for Roughing versus Finishing and also for Conservative versus Aggressive using our Tortoise Hare slider.  It’s quick and easy, and it solves a basic problem everyone has.  Not all cuts are equal.  Hobbyists want to maximize different factors than Pros in many cases (though not as different as you might think).  Sometimes you want to remove material aggressively.  Sometimes you’re after a fine finish.  Sometimes you are willing to go slower for better Tool Life.  Whether you have a “Full Tortoise” kind of application or need to get going “Full Hare,” G-Wizard is there for you.
  • Limit Feeds and Speeds gracefully based on the limitations of your machine’s horsepower, rpm range (both minimum and maximum), and feedrate capabilities.  This is not an especially easy thing to do in a spreadsheet because it is an iterative solution of many variables.  It’s particularly important for small machines that have many limitations, but even big machines have such limitations depending on what you’re trying to do.
  • Accurately predict and warn when tool deflection is a problem.  I’ve written so many times before about the perils of tool deflection.  Some out there think there is some magic deflection number that breaks the tool very quickly.  That’s true, but you’ve got serious problems way before you get that far.  Deflection can make your cuts inaccurate, ruin surface finish, shorten tool life dramatically, break cutters suddenly in mysterious ways, and encourage chatter which makes all that even worse.
  • Help you choose Cut Width and Cut Depth to avoid too much deflection while maximizing your material removal rates.  We offer both the Cut Optimizer and the CADCAM Wizards to do this.  For a good discussion of when to use each, try this article.
  • Compensate for a myriad of geometry effects on feeds and speeds.  Did you know that feeding too slowly is almost the worst thing you can do because of rubbing?  G-Wizard has a rubbing warning to help you avoid that.  Have you heard of radial chip thinning?  Any time your cut width is less than half the diameter of your cutter, your feedrates are not what you think.  You may have rubbing even though you think you’re going plenty fast enough if you don’t account for chip thinning.  How about ballnose compensation?  Lead Angle compensation? These are all important exceptions to the basic feed and speed calculations that have to be carefully factored in to make sure you get the results you’re hoping for.  If you’re curious about all these things, have a look at our Feeds and Speeds Cookbook.  It’s a free in-depth course consisting of bite-sized chapters covering every aspect of Feeds and Speeds.  Or, just leave all that to G-Wizard–it’s all built into the core Feeds and Speeds engine there.
  • Tune up the results for more tool types than any other calculator offers.  G-Wizard lists some 37 different cutter types on the Tool Menu when you consider the roughing and form vs cut tap options as well.  In addition, the Geometry menu adds another 40 variations.  Need specialized cutters for routers such as downcut, compression, or straight flute?  Done.  Parabolic vs Standard Twist Drills?  Done.  Ballnose, V-Bit, Chamfer, serrated rougher, and more?  Done and done.  And we add more all the time.  I haven’t even mentioned all the choices for Turning applications either.  You do sometimes use a lathe too, right?  These are just the easy menu choices.  Then you do things like specify taper angles and other critical dimensions of the tool that are considered in the calculations.
  • High Speed Machining compensation.  This can be something of a Black Art for many.  We have many who sell Tooling using G-Wizard to help them make recommendations and consult with their customers specifically because of this capability.  HSM is a deep subject, and one worth reading more about.  Suffice to say that G-Wizard was the first full-on HSM Feeds and Speeds Calculator on the market and it is still the best.  Don’t think it’s for your Hobby machine?  With the advent of inexpensive but high quality CAM in products like Fusion 360, everyone can benefit from the advantages of HSM.  Give it a try, you won’t be disappointed.
  • Tooling Suggestions.  I had a fellow approach me one time because he was breaking endmills right and left.  He was convinced he had a Feeds and Speeds problem.  He had 6 years of experience in CNC, having done a tremendous amount of work cutting wax models to be cast into jewelry on a small CNC machine.  Turns out his problem was he had switched to aluminum without realizing it’s a bad idea to use 4 flute cutters in aluminum–they don’t have enough room between the flutes to clear the larger chips aluminum makes.  My conversation helping him together with some other ideas I had percolating at the time led to the creation of CADCAM Wizards.  CADCAM Wizards ask very few questions and give you a lot of information back in exchange, including a recommendation for what cutter would be best for the job at hand.
  • Tips:  You ever read through a Tooling Catalog?  It’s something I love to do, and I have collected literally hundreds of them.  They are laced with valuable tips–how deep can I go with a twist drill before I need parabolic flutes?  When is conventional milling better than climb milling?  Most CNC’ers will always climb mill, but it’s not the best thing for every situation.  I love those valuable hints, but there’s no way I could commit them all to memory and be sure I’d always use them.  So I built them into G-Wizard.  It has literally hundreds of Tip messages it gives for various special situations to help you get better results.

I could go on like this for at least as many more bullets.  I haven’t even touched on things like G-Wizard’s extensive Material Database or it’s specialized “Mini-Calculators” for things like Interpolation, Ramping, Plunge Milling, and Ballnose Scallop Size.  That’s all there and more.

I have heard folks say they think they can create a spreadsheet that does what G-Wizard does, at least well enough for their Hobby needs.  Trust me–I have a ton of experience with spreadsheets.  I was one of the main developers of Quattro Pro back in the day, and founded the company that created its precursor.  I started G-Wizard as a gigantic Excel spreadsheet and I eventually gave up on it and switched to writing the software because Excel just couldn’t do all the calculations needed.  FWIW, one of our competitors also started as a spreadsheet that was attempting to reverse engineer G-Wizard.  They also gave up and started writing software.  Our Feeds and Speeds Survey revealed that the vast majority of machinists use a Feeds and Speeds Calculator, not spreadsheets.  They do that for a reason.

G-Wizard Tuned Up With Full Knowledge of Your Machine

G-Wizard can be tremendously helpful with minimal configuration as we’ve seen, but with full knowledge of your machine’s capabilities, it will do even more.  It’s worth your time after you’ve used it a bit, to give it some more information to chew on.  Here’s what’s needed:

  • Power Curve Adjustment and Machine Rigidity Adjustment:  Whether you have a larger machine with a power curve, or a lighter machine that may have rigidity limitations, we’ve got you covered.  Here’s the best article on how to set it up.  If you wonder what this rigidity adjustment thing is, here’s the theory behind it.  You can cut pretty much any material on a light machine provided the rpm and feedrate speeds are compatible with the material (i.e. if you can’t spin the tool slow enough to keep from burning it up in a hard material, you’re out of luck).  With G-Wizard and a few other tricks, we’ve seen people do amazing things.  Machine Rigidity Adjustment is a feature some of the power users of the very lightest machines have told me has finally gotten them results comparable to the bigger machines when it comes to accuracy and surface finish.
  • Coolant Options:  This is a Big Industrial Machine feature, for the most part.  Coolant is hugely valuable for increasing the throughput of your CNC machine, but perhaps not always in the way you might think.  It’s less about the “cooling” and more about chip clearing and lubrication.  If you have premium coolant options including programmable coolant nozzle, through spindle coolant, or high pressure coolant, G-Wizard will adjust its Feeds and Speeds accordingly.  You may see 40% or more increase in your material removal rates–no small feat!

G-Wizard Tuned Up With Full Knowledge of Your Tooling

G-Wizard is calibrated via statistical analysis of a very large collection of tooling data–about 250 different tooling catalogs.  The statistical analysis is much more complex than this, but let’s think about it as a simple average with a minimum and a maximum.  G-Wizard is calibrated to be a little above the average.   In other words, it’s calibrated to be relatively conservative versus that data.  I get very few calls from people breaking tools as a result, and that’s a good thing.  G-Wizard aims for what we call “Toolroom Feeds and Speeds.”  The Toolroom does a lot of one-off work.  They’re not trying to eek out the last few pennies of profit on a giant production run.  Breaking a tool may be very costly if it results in the part being scrapped.

People often get in touch to say they can’t believe their cutters will survive G-Wizard’s recommendations.  After checking about their use of coolant and potential runout, I suggest they get started with a Tortoise-Hare setting closer to the Tortoise end for comfort, and then gradually ramp to Full Hare.  They’re usually very happily surprised at just how fast they can go.  But then many of them want more.  The easiest way to get more is to give G-Wizard more knowledge of your Tooling, and it is very easy indeed to do that.  This page describes exactly how to calibrate based on what the tooling manufacturer recommends.  As you will see if you visit the page, it is super easy.  And, you can put those settings into Tool Crib entries so you look them up once and then they are available for you to use any time you want.

This is particularly powerful with indexable tooling.  There are so many different inserts available, that any generic assumptions are by definition going to be extremely conservative.  Plugging in a little more info will unlock a lot more power in most cases.  The same is true if you’re buying premium tooling–unlock the extra power that you’re paying for with a few simple steps.  Put all that micrograin carbide and special geometry to good use.

G-Wizard Tuned Up With Full Knowledge of Your Shop’s Best Practices and the Limits of Your Machine and Tooling Combinations

So you’ve got G-Wizard fully dialed in on your machine’s capabilities and the tooling you’re using.  Congratulations–I can tell you from experience you’re now ahead of probably 80% of the commercial machining world by doing this much, and G-Wizard made it pretty straightforward to do so.  But it’s possible to unlock even more power if you’re willing to give G-Wizard even more information.

G-Wizard has a capability called “Knowledge Based Machining.”  This is a capability that is reserved for the most expensive CAM packages, and most of them don’t really apply it successfully to Feeds and Speeds so much as other CAM-related issues.  Think of it as teaching G-Wizard where the absolute edge of the performance envelope lies so you can take advantage of that knowledge on future jobs.  The secret to Knowledge Based Machining in G-Wizard is a feature we call the Cut KB, which is short for Cut Knowledge Base.  Think of it as a helpful diary in the form of a database for tracking the results you get from various Feeds and Speeds.  You add an extry to the Cut KB by setting up the Feeds and Speeds in G-Wizard and then clicking the “Add to Cut KB” button at the bottom.  It will pop up this screen:


Adding to the Cut KB…

What comes up is a screen that records all the important information about the cut, but it also provides you the opportunity to add subjective information:

  • Overall rating with 0-5 stars
  • What was the wear like?  Choices are Normal, Poor, Chipped, and Broken.
  • How much (if any) chatter was encountered?
  • Exactly what kind of operation was being performed?  Peripheral milling, pocketing, slotting, etc.
  • etc.

There’s enough information being recorded to serve a lot of purposes.  For example, chatter is a very reproducible phenomenon and you will see in advance if you’re choosing a combination that’s been chatter prone in the past.  To use the Cut KB, simply record all your cuts and then when you have built up some data, start using the “Search Cut KB” button.  After you’ve set up a cut in Feeds and Speeds, click Search Cut KB and you’ll see prior cuts that are similar.  By strategically running tests that find the limits of Tool Life and Chatter, you will map out the edge of the performance envelope and see how much faster you can go than the basic Feeds and Speeds recommendations.  You can customize G-Wizard further by adding correction factors to Tooling Entries in the Crib or to the Machine Profile itself.  Perhaps you’ve found you never have a problem on your big Horizontal Mill if you run 5% more rpm and 15% more feedrate.  Just bake that in and G-Wizard will start producing recommendations based on that.  From there, the individual cut types will inform even more performance.  You can often go faster peripheral milling than pocketing, for example, because chip clearing is better.

If you’re willing to invest the time, Knowledge Based Machining can unlock considerably more profit for your shop.  It’s really the ultimate in Feeds and Speeds productivity, and the thing is, you don’t have to invest the time all at once.  Try running a little faster on each job until you find the limits.  Cut KB is the record keeping tool that makes tracking it all easy.


I hope by now you will have seen that G-Wizard is a deep product that can offer a lot to Professionals and Hobbyists alike.  The more you give it, the more it will give back.  But it’s prepared to give quite a lot right out of the box with minimal effort.  Find out for yourself what it can do–we offer a free 30-day trial.  Be sure to check the many links we’ve scattered throughout the article because that’s another thing that’s unique to G-Wizard and CNCCookbook–we have thousands of articles about nearly any CNC topic you can imagine and about every aspect of our software.  We can help you understand not just how but also when and why.  We’re constantly trying to get better at helping anyone become a better CNC’er.


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Recently updated on May 24th, 2024 at 07:17 am