FreeCad Inlay (Part 2)

 This post will be using the SVG saved as Base in Part 1.

Click image to enlarge

This post will be focused on the red base in the image above.  The same 60 degree v-bit from Part 1 is used.  Take note of the 0.100" depth of cut,  the 0.050" prismatic over-cut,  and the small green triangle representing the prismatic offset.  There is a note mentioning sanding to create the other gap shown but I haven't found this to be necessary in practice.

Oh No ! It's trigonometry !

    The triangle on the left represents the green triangle in the sketch above.  To achieve the .050" gap the perimeter of the Base pocket needs to be inset 0.029"

tan30 * 0.050 = 0.029

The tool path for the v-cutter also needs to be inset.  In the image to the left the blue triangle represents the material the cutter will be removing removing to achieve a 0.100" depth of cut.

tan30 * 0.100 = 0.0577

0.0577 * 2 = 0.1155

0.1155" is the full width of cut

 

 

 

A description of what happens next

The image on the left is the Base SVG modified for illustration purposes.  The thin green outer border represents the full size of the Base SVG.  This green border is 0.029" wide and will be deleted.  The red represents the 0.1155" wide v-carve cut.  The green area in the interior will be removed in a clearing operation.

 

 

 

 

Yikes ! It's Inkscape !

Inkscape 0.91 is used here. 

You were warned this was coming in Part 1.  The Base SVG is modified here.  Get rid of any fill and apply a stroke if necessary.  Set document properties to inches.

1  Edit -> Preferences -> Behaviour -> Steps.  Change Inset/Outset  to 0.029"

2  Select the path outline and then apply Path -> Inset.  This will be the pocket perimeter.

3  Return to Preferences and change the steps to 0.1155"

4  Make a duplicate of the current path.

5  Apply Path -> Inset

6  Select the outside path and apply a black fill.  The SVG should now look like a solid black diamond.

7  Ctrl + A to select all.

8  Path -> Difference.  If all went well there should be a black diamond perimeter with a white centre.

9  Save the file as an Inkscape SVG

Finally FreeCad Time

1  Import the SVG into the Draft Workbench

2  Select the outside path then the inside path.  These may be a bit obscured.

3  Modify -> downgrade to create a cut.

4  Repeat Modify -> downgrade to create a face.

 

This post got too long.  Continued in Part 3