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

It was the ability to change what prefix to remove. As i live in Denmark, whenever i make a call on a land-line there is no reason to dial +45, which is the danish country code. Actually the plus is converted into 00 as well.

But Eli needed the prefix 08 to be removed.

And i guess that there are a lot of other prefixes that could be removed and + shouldn’t always be converted to 00. So I decided to implement this feature.

Whats new

• It now remembers your settings
• It possible to choose a prefix to remove
• its possible to decide what + should be replaced by.
• I slapped a GPL V3 license on it

The files

dtmfdialer jad file

dtmfdialer jar file

dtmfdialer source code

Unfortunately it wasn’t just a 5 min hack. There were two major challenges.

Persistence

In J2me access to the filesystem is restricted and requires all sorts of security permissions, but every application has access to a “RecordStore”. The RecordStore (RMS) only allows byte[] to be stored, so you have to marshall/unmarshall every piece of data at quite a low level. I haven’t persisted any data in the first version, as this is indeed tedious to work with. But not having persistence for a prefix remover functionality wouldn’t be of any use. You would have to enter the same data every time you used the application and then it would be faster to just edit the number to call.

Netbeans mobility pack

It was supposed to be so eays.

But the floweditor somehow did mess up and didn’t generate the code, so the flow diagram and the sourcecode were out of sync, and i didn’t see any way to “resync”/”regenerate code/diagram”. This was cause for a lot of frustrations.

Originally i made it with netbeans so compiling and editing the generated code were best done in netbeans. But if i ever were to mess with it again i would seriosly consider “porting” it to J2me Polish or just “vanillia” j2me. As i really really don’t like the netbeans editor.

update : Eli found a bug in the prefix substitution, i fixed and uploaded the new version (June 27, 2009, 21:17)

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”

I googled around but weren’t able to find such a utility. But i did find cli-sip client pjsua, based on pjsip. Its posible to use it in conjunction with a shell script.

Scripting

jacob@vps:~./control.sh sip:108329@foobar.com "wake up you lazy bastard!"
Is the basic usage i wanted to have. In order to get this functionality there are two steps.

Generating wav file

I ust use text2wave, from festival, which is available as a package on ubuntu.
echo $2 | text2wave - -o message.wav

$2 to use the second argument, and pipe it to text2wave. Let text2wave read sdtin and output a file message.wav

Call and play the wav file

pjsua_app --config-file=test.conf --play-file message.wav $1
Here the magic is in the conf file. Its a rather straightforward to use, and the documentation is good.

# we don't want the host's audio device
--null-audio
# SIP parameters
--realm domain.com
--registrar sip:number@domain.dk # DNS SRV, or FQDN
--username USERNAME
--password PASS
# default of 55 will be rejected as being too short by sipX
--reg-timeout 3600
# auto-answer all calls with "200 OK"
--auto-answer 200
# automatically loop incoming RTP to outgoing RTP
--auto-loop
# mix WAV file into the audio stream
--auto-play
--auto-loop
--duration=60

This is based on a config file i found somewhere, can’t remember where. There a a lot of other options, pjsua handles nat quite nicely as well. It was easy to test it at my homebox, behind a router, just be sure to set an external ip address.

Now this will call and play the message, but it wont stop pjsua. It will just sit around waiting for someone to call. I couldn’t find any nice way to handle this, but since pjsua reads stdin for commands, it possible to pipe commands to it.
echo "sleep 60000 q" | pjsua_app --config-file=test.conf --play-file message.wav $1
So sleep for 60 seconds, then accept the next input from stdin, the “q”uit command.

Generally this configuration is set for 1 minute, it might be necessary to tweak this.

Frustrations

There is/were a bug in the tarball, that meant that it wouldn’t run if it couldn’t find a soundcard, since it should run on a vps this is quite annoying. But in the svn version its solved, so if you want to do something like this, use the svn version. Other than this installation is straightforward.

When working with cron, remember to use full paths. In the control.sh script the better solution were to add a cd working directory, in order to have all the paths correct. This were quite annoying to debug, as the script would run from the shell. And just fail when added to the crontab. Furthermore mails from crontab were delayed, so i couldn’t see the output. I did get someone to look over my shoulder and spot the bug.

It would have been fun get a quick hack up and running today.

Identi.ca is like twitter, but just better. Its open source and the system with groups and tags doesn’t seem to exist to the same degree in twitter.

I added a widget to show the latest updates from identi.ca to the blog (Identi.ca Tools)