FlatCAM pratical tutorial: clean non copper area – Part 3

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When you mill a PCB traces probably remain some islands of copper and here can remain a floating potential that can create disturbances, so if you create an high frequency PCB It’s better to remove they.
Remember you can put the area on ground and you can fix the problem.

To remove island you can follow 2 approach, first is to use directly NCC Tool (Clear N-copper), and you are going directly to remove all copper in the area you select, or first do isolation (look at the previous chapter) and next go to remove islands of copper.

Clear residual non copper area

I continue from previous part, here a screen with some arrows to identify the islands

FlatCAM islands of copper
FlatCAM islands of copper

and we are going to remove the islands, you must select the more external geometry generated

  • PCB_PCF8574_03_copperBottom.gbl_iso1
  • PCB_PCF8574_03_copperBottom.gbl_iso2
  • PCB_PCF8574_03_copperBottom.gbl_iso3 <– more external

Simply select more external geometry and click on NCC Tool button, a panel Non-Copper Clearing is shown

FlatCAM non copper clearing selection of area
FlatCAM non copper clearing selection of area

As you can see in the upper part (red arrow) you can select the Gerber or Geometry this choice because you can land on this panel via menù also with Tool --> Non-Copper Clearing.

Single tool without change

Than we can select one or more tool (blue arrow), in this example we continue with the same tool used with the Copper isolation so when you set a Tool Dia you put 0.55 or other value as you put in the previous Copper Isolation.

Than you can put a correct Cut Z (but in the generation of GCode you must reinsert It), default value is 0,05, but I normally put 0,07 or better 0,08.

Overlap Rate have the same behaivor explained in the previous part.

For this specified situation, margin (yellow arrow) is set to 0.2, but we remove It because we are going to extend the area to be sure that no residual remain.

Method: now here you can select a method of geometry generation, standard is the creation of concentric border, and is in line with the previous work (in the next paragraph I’m going to explain the various method).

Connect: simple try to do all without stop milling, create a long continous line;
Countour: first create a border to prevent bad margin;
Rest. M.: is used with multi size tool, we explain better next.
Offset: dislike margin here you can add a safe area not from all but only from copper to prevent problems.

Reference:

  • Itself: is applied to the Gerber or Geometry selected upper;
  • Area Selection: you can select a specified area;
  • Reference Object: you can select another object different from reference object selected upper.

We are going to do all with area selection, than when you click on Generate geometry button (pay attention on error in left bottom of window) nothing append and you must select the area.

FlatCAM non copper clearing selection of area selected
FlatCAM non copper clearing selection of area selected

The step to follow are:

  1. click on the angle of the region you want select;
  2. click to the end of area;
  3. repeat for all areas you want clean;
  4. when you finish click with right mouse button and the action start.
FlatCAM islands of copper removed
FlatCAM islands of copper removed

With the same tool, all line is parallel and concentric and you mantain the same tool for all.

Multiple tool with different size

You can select a tool with bigger diameter for the big area and a little more tool for the angle: you must add the tool on the upper grid, and you must insert in the “default” tool the more little diameter tool.

FlatCAM non copper clearing selection of area multi tools
FlatCAM non copper clearing selection of area multi tools

In Tool Table I add 2 tools one with 2mm diameter (for rough remove) and one the classic 0,55mm. You must select Rest M. and select all tools in the table, than Generate Geometry. Select area as explained and the result is here

FlatCAM non copper clearing selection of area multi tools selected
FlatCAM non copper clearing selection of area multi tools selected

In the bigger area you can see a line generated by tool of 2mm at the margin the tool of 0,55mm.

Mill all with Non-Copper Clearing

Now restore the pcf8574 project after basic import (Part 1), than select PCB_PCF8574_03_copperBottom.gbl and on Gerber object panel select NCC Tool button.

Now we must pay attention on margin, this value It’s important to get a good work.

FlatCAM full non copper clearing It self copper no margin
FlatCAM full non copper clearing It self copper no margin

You must select PCB_PCF8574_03_copperBottom.gbl on Object and Itself as Reference.

Now here a result without margin (margin set to 0).

FlatCAM full non copper clearing It Self no margin result
FlatCAM full non copper clearing It Self no margin result

Without margin outside the border of gerber some part of work isn’t covered, here a result with 2mm margin

FlatCAM full non copper clearing It Self with margin result
FlatCAM full non copper clearing It Self with margin result

Now as shown upper you can add multi tools with Rest M. parameter, so if you add a 2mm tool and a 0,55mm tool on table tool (remember to add the tool with lesser diameter to default) and select Rest M. you obtain an element like so:

FlatCAM full non copper clearing It Self with margin result multi tools
FlatCAM full non copper clearing It Self with margin result multi tools

Result

Here the result with the use of the same tool

FlatCAM PCB pcf8574 clean copper islands
FlatCAM PCB pcf8574 clean copper islands

Thanks

  1. FlatCAM pratical tutorial: introduction, installation and import
  2. FlatCAM pratical tutorial: copper traces geometry
  3. FlatCAM pratical tutorial: clean non copper area
  4. FlatCAM pratical tutorial: silkscreen geometry
  5. FlatCAM pratical tutorial: contour
  6. FlatCAM pratical tutorial: gcode and PCB milling

You can find Gerber, fritzing, images and FlatCAM project files here.


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