Information on the relationship between HSM and its post-processor.

[matevzic.domen]

Hello,

I need some basic information on how G-code is generated.

Correct me if I'm wrong: In Autodesk Inventor HSM you select the operation you want to work with and set the parameters on how the tool should move. Based on this information, the toolpath is generated. The toolpath is assembled using points, which can be seen in the simulation.
When you hit post-processor these points are converted into G-code.

My question based on this is:

• If the above statement is correct then the post-processor can't influence when G1, G2, G3, etc. are used?
• If the above statement is not correct then the post-processor determines when to use G1, G2, G3, etc.? If this is the case, can you code CPS of the post-processor in such a way that will generate g-code without using so many points? or use those points to generate more complete code by implementing new G-addresses and M-functions, like G42 and M60 for example.

I'm interested in giving a fresh rework for my post-processor and when talking to companies which specialized in this, they asked a lot of money for it. So I'm curious if this is even possible.

Best regards

Domen Matevžič

[matty.fuller]

Neither of your statements are correct, but a mix of them is close.

Firstly, read the manual: https://cam.autodesk.com/posts/posts/guides/Post%20Processor%20Training%20Guide.pdf

The post processor is a library of functions that are called by the CAM kernel at certain points in the program... eg:

onOpen() is called at the start and is where you set up the machine and general parameters.

onSection() is called at the start of each operation and is where you might change tools etc.

onLinear() and onCircular() are called for G1 and G2/G3 moves and helps format the output for those blocks.

Within the post you can do whatever maths, logic, and transformations you need to, and you can turn a G2/G3 into a series of G1s (linearize) if you want. Reducing the number of points could be as simple as using smoothing inside HSM or changing the tolerance.

Knowing what all the parts of the post do, what to change and what that might break, for a variety of different and highly specific machine controls... takes time and hard work. That's why people charge a lot to do it for you.