Recently a user of G-Wizard Calculator asked to understand better the difference between Calculator’s CADCAM Wizards and its Feeds and Speeds Calculator. It’s a fair question as they look totally different and the CADCAM Wizards are so unique nobody will have had experience with anything like them before they tried G-Wizard.
Let’s start with the Feeds/Speeds Calculator. It’s familiar to any machinist because it presents concepts that have been around for a long time:
The Feeds/Speeds Calculator presents concepts familiar to almost every machinist…
The idea is you work your way through, left to right, top to bottom, until you’ve filled in enough blanks to get back RPM and Feedrate. That basically means filling in the sections labeled “Machine”, “Tool”, and “Cut”. The Mini-Calcs are specialized little calculators that help you with specific problems like Interpolated Holes, Ramping into a Cut, and Plunge Roughing. The answers appear in the “Feeds” section, and the areas below “Feeds” are optional areas to fill in. You can override almost anything G-Wizard calculates and force it to deal with that. For example, you might want to arbitrarily reduce the RPM’s, or you might want to provide your cutter manufacturer’s chip load and surface speed. Most of the time, you’ll just leave those areas alone having already set most of them up when you created a Machine Profile.
That’s all there is to it, and it is a familiar way of approaching the problem. Why then, do we need CADCAM Wizards? What are they good for and when are they better?
The answer to those questions comes about first by looking at the questions many users ask:
– How do I determine the best Cut Depth and Cut Width for my job?
– How can I optimize the trade offs between the myriad strategies available to machine a feature and pick the best one?
– How can I answer the questions my CAM software wants me to answer as quickly, easily, and optimally as possible?
– And one for beginners: How would I have known I shouldn’t use a 4 flute endmill when slotting aluminum?
One thing I have found is true throughout most of my 30 year career in computer software is that computers often answer the questions they want to, and those questions may not be exactly the questions I need them to answer. We make due with this state of affairs until someone writes some new software that does a better job answering the questions I really wanted to ask. We made do with pure accounting software, yellow pads, and 10 key calculators before spreadsheet software was available. When it showed up, it didn’t obsolete any of those things (my CPA wife still uses all three!), but it sure did make answering certain questions and performing certain tasks a whole lot easier.
CADCAM Wizard is this sort of thing. The traditional Feeds/Speeds calculator is very flexible, but it is also very low level. It works as well for manual machinists as for CNC machinists. But what it doesn’t do very well is help on the sorts of questions I just posed. G-Wizard was the first software I ever saw that helped give a scientific answer to the question of how much Cut Width or how much Cut Depth to use. It did this with the Cut Optimizer, which can solve one or the other problem (Depth or Width), but not both. So you’d choose one value. For example, you know when slotting that at least some of the cut has to be made at full cutter width. So you click the “Slot” button over by Cut Width to dial in the tool’s diameter. Then you click the little speedometer next to Cut Depth and Cut Optimizer will tell you the maximum depth of cut you can take without encountering too much tool deflection:
Given either Cut Depth or Cut Width, Cut Optimizer can tell you the maximum value of the other…
In this case, we can take our 1/2″ cutter down that 0.5″ slot to a maximum of 0.6119″ depth of cut. Folks loved the Cut Optimizer and it was a big part of G-Wizard’s success, but there were still many more “typical” questions users wanted answers for. In particular, they needed answers for their CAM software, which looks at the machining problem in a particular way and doesn’t care about much else. Another whole set of questions that CADCAM Wizard addresses are the questions that come up when estimating costs so jobs can be quoted. In both cases, I wanted to create software that could answer all of these questions while requiring the user to provide as little information as possible, to make it faster and easier.
Here is the CADCAM Pocketing Wizard:
CADCAM Pocketing Wizard…
As you can see, it looks significantly different than Feeds/Speeds. To my eye, at least, it seems simpler. If you refer to the Feeds/Speeds screen, you must answer a minimum of 8 questions to get back Feeds and Speeds:
1. Machine: Which Machine Profile will make the cut?
4. Tool Diameter
5. Tool Flutes
6. Tool Stickout
7. Cut Depth
8. Cut Width
For CADCAM Wizard, only 4 questions must be answered to figure out how to do the pocket:
3. Depth: How deep is the pocket?
4. Minimum Corner Radius: What is the tightest corner in the pocket?
In exchange for answering fewer questions, you actually get quite a bit more information from CADCAM Wizard than you do from Feeds/Speeds:
1. It will recommend what tool to use based on the type of toolpath, the toolpath’s parameters (e.g. Min Corner Radius), and so on.
2. It will determine Cut Depth and Cut Width.
3. It will give you a step-by-step recipe for roughing and finishing passes that includes Cut Depth, Cut Width, number of passes, feeds and speeds, and timings for each step.
How does it come up with all that and how good are these answers compared to the tried and true way (we make a careful guess based on experience and go with that)?
The best way to answer that question is to understand how CADCAM Wizard goes about doing its work.
At this point, it is important to note that Feeds/Speeds and CADCAM Wizards use exactly the same code to calculate the feeds and speeds, so given all the same inputs, they will return the same answer. Think of CADCAM Wizard as being an extra employee, who is a pretty good machinist, who you delegate the operation of Feeds/Speeds to. You tell the CADCAM Wizard some basic high level stuff. In effect you say, “Hey Joe, I need a machining recipe for a pocket. The pocket is 2″ by 3″ in 4130 Steel. Figure out the best parameters for Cut Depth and Cut Width for a roughing pass, and also give me parameters for a finish pass that’s 0.015″. I need Feeds and Speeds for all that.”
It’s not hard to imagine Joe going off with G-Wizard and figuring all that out, saving you the trouble of doing it for yourself. Joe knows a bunch of things, what the computer people call “Expert System Rules.” He knows you don’t cut aluminum with 4 flutes. He knows that if G-Wizard’s Feeds/Speeds says there is a deflection problem that he doesn’t want to use those parameters. The thing about computers, is that you can program that sort of knowledge into them, but what they really do well is work tirelessly. This is where Joe may not be quite as good as CADCAM Wizard. If you look at the text box on the lower left, you’ll see that CADCAM Wizard tested 651 scenarios. That means it tried 651 different combinations of values to find the best answers. I’d be surprised if Joe had the patience to do something like that.
Now if these were just 651 random combinations and Joe was indeed a good machinist, I think I’d still put my money on Joe to get the best answer. But the CADCAM Wizard is a bit smarter than that. Yes, it starts out with a random combination, but then it uses some very sophisticated algorithms to take the best combinations discovered by the initial random tests and optimize them to be much much better in as few tests as possible. The best initial tests are in a competition to see which one can be optimized to be the overall winner.
Okay, but what is it that’s being optimized and is that what I really want?
The “winning ticket” has to respond to multiple metrics that matter in the machining world, here are a few:
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