Creating NC files from Blender 3d Bezier Curves

Chinese Char 'I LOVE YOU' Example - Adding Offset Toolpaths

This page describes one way to add pocketed paths to the Chinese 'I love you' character design.
This is a real quick overview - I'm showing what I know as soon as I know it.

The InkScape Offset command has two important uses when creating toolpaths:

First: To maintain accurate part sizes with *.nc files you need to offset the design contour by the cutter radius.
(this isn't very important for many of the things I do.... especially when the cutters are very small)

Second: Creating a series of offsets that will allow the cutter to 'Pocket' the design.
ie. machining out the 'filed' areas of a design.

To maintain sharp details I use small cutters for most of my work.
This also means that I usually have to pocket the design - ie. create multiple offset toolpaths.

Start with the lovyou.svg file loaded into InkScape:

Remove fill and add stroke (so you can see the offsets you will be creating):

remove fill add stroke

Offset the contour with the Linked Offset Command:
select the path and then type Ctrl+Alt+J to run the offset command

A single 'offset' node will appear, drag the Node to get the offset distance you want:

Add the second Linked Offset - Ctrl+Alt+J and then adjust the node:
note: there are some small unwanted curves generated- stuff I'd like to delete

Add third Linked Offset - Ctrl+Alt+J and then adjust the node:

Save the svg file:

Load the svg file into Blender:

Select InkScape:

Use the Import Options Defaults:
Clamp Height 1 loads the svg file into Blender with a height of 1 blender unit
Scaling the model in InkScape is certainly possible and may be desirable in the the future.
Rescaling the model in Blender is easy and, for now, seems to be the way to go.

This is what you should see:

Scale and Grab the design:
When cutting metal rings I use a 3-jaw chuck to hold the rings
I have defined the right edge of the ring = ring width and the left ring edge as 0.00.
For a 6mm wide ring you would want to scale the ring design so the Dim Y value is less than 6.0 (ie 5.148)
and the ring design located slightly above the x-axis

Export the bezier curves:

Make sure to rename the export file ext to .xyz

Run BezierNC.exe to create the toolpaths and *.doc xyz points file
BezierNC.exe has a few options - I hope they are self-explanitory..

In Titanium this is the final results:

Final Comments:

This page is a first draft - not everything has been shown.

Disclaimer: With the titanium ring pictured above I used beziernc.exe to generate contour toolpaths.
I then manipulated these contour toolpaths with my cad program to create a *.nc file which was used to machine the titanium ring

Creating toolpaths as described on this page using the InkScape offset command should give similar results
(I machined the titanium ring pictured above before I became aware of the InkScape Offset Command

The InkScape Offset command may generate artifacts
(crap you don't want is what I'm trying to say - ie. very small curves...
I'll try to eliminate these small curves in a future version of beziernc.exe
but for now you may want to remove them in Blender or InkScape)

Cutting titanium rings is quite a project and I use custom hardware which I've built.
I'll describe this hardware and the procedures I use in future pages.

That's it....for now
If you have any questions, corrections, easier ways to do things and/or comments..... please email me.

Roy Goodell 7/14/08
5xj@5xj.com