I measured the egg using the probe.

Create the path in in inkscape using gcodetools.

In a postprocess i first split the path in to short segments, then I linearly interpolate based on the measured data to follow the surface.

In this eggsperiment I used G64 to allow the machine some tolerance in following the path to gain a better feedrate. The result were at significantly different sound from the steppers, it sounds more ‘sick’. But it worked

See the video @ vimeo : http://vimeo.com/38699800

The next step is to try to make TSP art on the eggs, Nikolai Tesla made from a single line , Evil Mad scientists have nice guide: http://wiki.evilmadscience.com/TSP_art

These data were made with a ‘FrakenProbe’ they represent the surface height, X(length) and A(rotational)axis.

The experience with the first test run proved that even though the penholder does have some play in the z direction, the plot could be better if the pen were to follow the surface of the egg exactly.  Now its possible to probe the surface and the next step is to interpolate the movements based on the data.

A video of the frakenprobe in action on vimeo : http://vimeo.com/38466340

The gcode to probe the data were my first experience with writing loops in gcode and making extensive use of parameters. I must admit that it not pretty, this is the main part with a nested loop:

(PROBEOPEN data.txt)
G0 Z[#<SAFEZ>]
#<J> = 0
o200 DO
G0 A[#<J> * #<ASTEP>] Z[#<SAFEZ> + <#PZ>]
#<I> = 0
o100 DO
G0 X[#<I> * #<XSTEP>] Z[#<SAFEZ> + <#PZ>]
F300
G38.2 Z[#<PZ]
#<PZ> = [#5063]
#<I> = [#<I> + 1]
o100 WHILE [[#<I> * #<XSTEP>] lt #<W>]
#<J> = [#<J> + 1]
o200 WHILE [[#<J> * #<ASTEP>] lt 360]
(PROBECLOSE)

Did i mention that it is really really nice to have a hackerpace, with tools, parts, club mate and geeks who can help out when you are stuck.

A penholder was made, its basis is the insides from a CD-ROM drive the pen is molded into place using Shapelock.

An Egg was mounted and some quick test pattern were made in Inkscape.

We step back and observe the magic.

Unfortunately i dropped the first real image, the first test run were spirals and a hardboiled egg.

There are still issues to work out, but all in all we are quite satisfied with the first test.

Parts laying around, access to all the necessary tools and soon this will be an eggbot. It shall be mounted on a CNC machine as a rotary axis.

We will have machine painted easter eggs  at  Open Space Aarhus

The project as it looks so far :
I ordered a set with steppers, motor-control and psu from ebay, and I’m waiting for it to arrive(The seller said 10-12 days, so maybe if I am lucky next week). It should be 1.7NM motors and a more or less “plug’n’play” set.

I intend to drive the motors using a old computer running linuxcnc. linuxcnc looks real neat, but might prove to be hard to set up.

The construction

I am looking at two set of plans at the moment

How-to-Make-a-Three-Axis-CNC-Machine-Cheaply

This was the building plan that made me decide that this was a possible task. But there are some issues with the construction I don’t like, especially that it uses belts. They are hard to find and they are not cheap.

JGRO’s plans

This is a free diy plan. it can be found here : http://www.cncroutersource.com/cnc-router-plans.html

It uses threaded rod instead of belts. And the overall construction looks simpler.

Materials

Although I do want to do “fabbing” using a extruder at first I think that there will be enough work for a couple of days getting the mechanics and electronics up and running. Just as there is a lot to learn about g-code and all sorts of 3dmodelling.

To begin with I want to cut using a dremel tool, maybe a more powerful spindle(?) to be able to cut wood – if I have enough power in the steppers.

You might ask what do you want to make / “fab” with a 3 axis cnc machine?  I can come up with a lot of different small things like “coat hanger”, “coffee filter”, “PCBs” but I guess that it just boils down to: ” I think its a very fascinating technology and want to play with it”