Post Processor Overview

Every machine has it own language and particularities.

To get the same toolpath on different machines, may be necessary to customize the output g-code.

The customization is obtained editing the post processor.

Basic Concepts

Here some basic concept to understand , in order to customize the post processor.

1) 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 phase it's called a template and a dictionary, from the union of these two elements i get the output g-code.

See below for a pratical example.

2) Templates

Here an example of a template .

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}

3) Tags Dictionary

The tags are nothing more 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

And so on.

Where i can find the available tag list ?

4) 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