What are some common errors or issues that occur during CAD to G-code conversion and how do you fix them?

While I do agree that scale and unit conversion is a common factor when taking a part from model to physical part, I feel as though it is also prudent to point out that we are missing two very important steps in the process. In many subtractive manufacturing processes (milling and turning specifically), the machine needs to know which tooling (and parameters) are being applied as well as the syntax of the controller. In these cases, the flow is actually CAD to CAM (Computer Aided Manufacturing), to Post Processor to machine control. The machine never actually 'expects' a program to be any particular unit of measurement. This is called out in a properly set up program with a modal G20/G21 command, and the machine adjusts units accordingly.

This "case" is a rare occurrence that only happens when interchange formats are used somewhere in the middle. This makes me think that it's just written by an "AI", a language model that doesn't understand what it's "talking" about. ??????

I have a college degree in machining and almost 30 years of experience, and I have never heard of a machine “expecting” imperial or metric numbers. The question itself is perplexing. If this ever happens to you, immediately fire the programmer for incompetence.

Always model CAD in metric. The SI unit system converts well to any other unit. Everyone admit it, No one likes the unit of slugs. Also try to export it with as many elements as possible for accuracy. A universal CAD format that has spline data is STEP. I have found this to be the most compatible and accurate amongst all parametric CAD software I have used.

Your a beginner aren’t you, machine control don’t care, program a metric part and output in inch or vis versa. the biggest problem is designers modeling are pet at max or min tolerance and then dimensioning a + or -. You have to analyze the model

You want to avoid having a poor tessellated model in the first place. Model in solids and you will not have as many issues. However, sometimes surfaces are useful to make phenomenal shell models for 3D printing in spiral vase mode. In fact, sometimes 3D printing overlaps with surface models can be useful in creating very strong lightweight printed parts. In addition, it is useful to start with a good coordinate system, think of tool path plane 0 datum as xy plane with z up.

Sometimes lines on CAD have multiple segments, if CAM technician does not notice this, the machined part could have surface finish issues. Small spaces between lines, this happen when lines do not have Conexion between them. When geometry comes from a DXF file it happens sometimes that explode lines and make an unfixed shape.

CAD to G-code conversion, i.e. CAM and post processing steps, is an important area which causes a large waste problem in the machining industry. In general, the physics of the machining process is not considered in these steps. Manufacturing engineers mostly identify the problems such as tool breakages and vibrations during machining when it is already too late. This leads to many iterations on the machine tools which leads to increased lead times, extra resources such as extra engineering time, machine tool time, energy, workpiece material and cutting tools. Let's not forget the extra CO2 emissions. Digital twins for machining processes can eliminate these waste by identifying and mitigating the problems in advance.

There’s nothing in CAD data that will select speeds, feeds, tools, holders, etc. this is completely independent of CAD other than determining maximum tool size to machine a feature. And verification software wont help with speeds or feeds in a given material, it will merely show if a toolpath over or under cuts a feature, or if a holder, shank or fixture collision will occur. Speeds and feeds are based entirely on the machine’s capabilities and the tool type and geometry used. Just because X tool with Y parameters works on one machine, doesn’t mean it will work on a different machine or with a different tool. CAD is completely irrelevant to this process, again, other than tool size selection for specific features.

This entire write up is filled with strange scenarios that in my 20+ year’s programming and machining I have never once encountered. This seems to have been written by some one or some thing that has no knowledge of machining or CAM programming at all. And at best a cursory idea of manufacturing processes. It seems to make some odd implication that you take a CAD model, throw it into a “g-code generator” and it spits out a CNC program that you throw on a machine. That’s not how it works at all.

In my experience, the only time this ever happens is when an incompetent person has written or modified the post-processor. If this ever happens to you, fire that person. Machines do what people program them to do. Period.