Try TriSpiral Again

Decided to work on the gradient for the Tri Spiral and give it another go.  This time I used the Gimps shaped angular gradient to make the center of each arm of the spiral light and the outer edges dark.  After this I selected the white background and changed it to black.

This left the edge still with a little lighter shade then the black background.  Since I did not want the edge milled higher, I used the brush tool to write over all of this slightly lighter color with solid black.  This picture is before the final edit, notice the white on the edges.

Once the image was edited, I used EMCs image to gcode to convert it into gcode.  The first run in wood went pretty well.  The angles of the gradient are sharp so the arms are pointy, what I actually wanted was a little more rounded.  The fuzzys on the edges of arms are probably do to the type of wood grain in Cedar.

Next I decided to get brave and try and mill this out of some Plexiglas.  This was pretty much a disaster.  The first attempt, swirled the cut plastic around the bit, where it was trapped by the brush, this all melted very fast, and since I couldn’t see what was going on, actually melted to the bristles of the brush.  I spent 20 min or so cleaning the brush, freeing the bit, cleaning melted plastic off etc.

I changed my feed rate and slowed the spindle down, removed the brush and tried again.  The run went fine on the roughing passes that were only about .050 deep.  Then the code causes it to really dig in, down to the .250 final depth and this caused the plastic to melt and build up on the cutting bit again.  Eventually I had to stop as I lost steps and melted so much plastic the thing was “spiralling” out of hand, here is a shot for the scrap book.

I think this gradient method of adding 3D depth to pieces is worth exploring, some more.  Next, I think I am going to try and fatten some flat images up with the Gimp and use CamBams image to gcode feature.  Possibly I can control the amount that it removes each pass.   Still it takes a very long time to mill something this way.  However its quick to draw and work around existing images.  I will have to keep experimenting.


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