Post Processor Overview

IN THIS ARTICLE

Every cnc controller has a slightly different dialect, so you need to sure the generated g-code is compatible with your machine.

A post processor permits to convert the generated toolpath into readable g-code for your cnc machine.

Here you can download available post processor and here you can see how to open the post processor edit dialog .

If you can't find the information you need , please first use the search box and then ask me with contact form. I'll update the documentation.

Basic Concepts

Here a brief explanation to understand the workflow to convert toolpath into gcode.

NC Program stages

You can consider the nc-program as a sequence of stages , each stage has it's own template :

  1. G-Code Header
  2. For each operation
    1. Tool Change
    2. Tool Approach
    3. List of movements that make up the toolpath, or in some cases macros (drilling, tapping, etc ..)
    4. Tool disengagement
    5. Operation Finalization
  3. G-Code Footer

For each of these phases it's called a  template and a tags dictionary, from the union of these two elements you get the output g-code.


Templates

Here an example of a template , which is nothing more of plain text .

Inside this text , you can see some word between curly brackets. These are the TAGS.

{EMPTY_LINE}
{LINE_N}
({OP_DESC})
{RADIUS_COMP_INFO}
({TOOL_LABEL})
T{TOOL_POS}M6
{NEXT_TOOL_POS}
{FEED_MODE}
S{SPEED_VALUE}{SPINDLE_ORIENTATION}
{ORIGIN}
{COOLANT_CODE}

Tags Dictionary

The tags are the variable values, here an example of a tags dictonary.

LINE_N = N5
TOOL_POS = 15
NEXT_TOOL_POS = 10
FEED_MODE = G98
SPEED_VALUE = 2387
SPEED_ORIENTATION = M3
ORIGIN = G54
COOLANT_CODE= M8

Where i can find the available tag list ?

Output Final Code

From the combination of the single template and the tag dictionary, the output g-code will be created.

N5
(CONTOUR - ROUGHING)
(COMP COMPUTER - RADIUS COR VALUE 10)
(R390 D 20MM)
T15M6
T10
G98
S2387M3
G54
M8
...

The tag value will replace the {TAG_WORD} in the template.


Dictionary Convention

To facilitate understanding of the parameters available in the dictionary , it's been used a convention for naming tags.

Suffix _CODE :

These tags values are complete with both the char ( F, G, M) and numeric part ( 100, 0.3) 

example :

{FEED_CODE} => F.3

{SPEED_CODE} => S100

Suffix _VALUE :

These tags values contain only the numeric part ( 100, 0.3) .

example:

{FEED_VALUE} => .3

{SPEED_VALUE} => 100

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