Congresswoman Louise Slaughter visits the Space.

Congresswoman Louis Slaughter visit to Interlock centered around the idea that a small group of people can make an impact and rediscover the future. I may be embellishing a little but I do think there was a sense that even if we did not always agree that the conversation is always worth having. The 3D printers were a big hit as they usually are and Skip was on hand to demonstrate a few of his “little” projects.

Here Skip shows how the 3D printed prosthetic hand works to the Congressman. The hands are being made for e-NABLE an organization networking volunteers using 3D printers to make and give hands to children.

from on July 1st, 2014Comments0 Comments

Raspberry Pi IP audio announcement: ippivox



So, you can ssh into your Raspberry Pi, even if you don’t have any HDMI-capable display equipment at hand.  The trick, though, is knowing what IP address gets assigned to the Pi so that you know what to feed into your ssh client.

Earlier, these pages addressed this problem using VNC to provide a remote Raspberry Pi display (eg, from your laptop).  It’s a good approach, well documented.

Alternately, with a little bit of prep work, perhaps using the above technique to get everything set up to start, you can program your Pi to announce its IP address via audio using text-to-speech.


Much cheaper output than a HDMI-capable monitor

The essence of this trick is to install a text-to-speech program, create a small script to extract the IP address, to pass that address to the text-to-speech program, and then finally to configure the initialization scripts to run the readout script shortly after booting.

I’m working with a rev B Raspberry Pi running Raspbian, but the approach should be generalizable to any distro for which a TTS package is available.

First, set up the Raspberry Pi with keyboard, mouse, wired networking, and video, either HDMI or analog.  If you use analog, you may need to increase the font size considerably even to be able to read the screen.  Open a terminal and install festival:

sudo apt-get install festival

Next, if you haven’t already done so, create a bin directory in your home directory to hold this and other small local scripts and programs:

mkdir ~/bin

Then, open your favorite editor to create a small script file containing the following:

/usr/bin/amixer cset numid=3 1
/sbin/ifconfig | /bin/grep -A3 eth0 | /bin/grep inet | \
/usr/bin/tr ':' ' ' | /usr/bin/cut -d\ -f 13 | \
/usr/bin/festival --tts

Be careful if you try to copy-and-paste that that a) you get the single-quotes carried over into the right place and b) that you don’t have any space or tab or other otherwise hard-to-see non-newline whitespace characters at the end of the lines with backslashes. If either error crops up, edit to fix.

(NB: ifconfig is a bit old school. Interlock HAM and rally enthusiast HoopyCat points out that to be fully kids-these-days compliant, one should use the ip command.)

Save the file as /home/pi/bin/ and give it execute permissions with chmod a+x /home/pi/bin/

You can now test it by typing


into your terminal with a speaker or earphones plugged in. If you are connected to a network (and if not, how did you get festival downloaded?) you should hear the IPv4 address read off. If not, run ifconfig to check to make sure you do have IPv4 address (“inet”) assigned, and that it is assigned to eth0. If it’s assigned to something other than eth0, modify the script above to suit.

Finally, to make this work at boot time, open the file


in an editor and add at the very bottom this one line


Save, reboot, and listen for the IP address to be read to you.

If it works, then you can dispense with attaching a video output device when it comes time to hack on the Pi in favor of just logging in from a machine elsewhere on the same network using ssh.

I find it useful to play a short alert announcement before the IP address is read. I also use a second TTS program, flite, both to give me a second shot at hearing the IP and also in hopes that I’ll be better able to understand at least one of them.

My more lengthy approach to this is documented in the following github gist:

Thanks go Matt via the Raspberry Pi blog for this tip on configuring the audio.

from on June 24th, 2014Comments2 Comments

Filament Nudger for 3Doodler

For various reasons, the 3Doodler sometimes stops extruding. This can happen with any 3D Printer. However, the 3Doodler is exceptionally easy to get going again by giving the filament a gentle nudge. The Filament Nudger is a hack to reduce the number of times the 3Doodler stalls or jams by providing a continuously nudging force on the filament.

Nudger without handle

3Doodler with Filament Nudger

The Nudger works with or without the Phaser Handle described in a previous blog : How to 3D-print a Handle and Trigger for the 3Doodler (and to make it look like a Phaser)    If you have access to a 3D printer, you can build a Nudger yourself by downloading these files on Thingiverse.

With handle

3Doodler with Phaser Handle and Filament Nudger

The automatic Filament Nudger was designed to be powered by a pair of rubber bands,  and it is cocked by pulling back on the Filament Grabber mechanism.

Cocking the Nudger

Cocking the Filament Nudger

The Grabber works like a 1-way clutch, pulling the filament toward the 3Doodler but releasing the filament when pulled in the other direction or when the Grabber bumps the back of the 3Doodler. The force applied by the rubber bands is effective in keeping the extruder going, but is not strong enough to prevent the filament retraction which conveniently keeps the 3Doodler from oozing between extrusions like a glue gun does.

Filament Nudger works with filament provided by 3Doodler

Filament Nudger works with filament provided by 3Doodler

When used with the filament sticks provided by 3Doodler, the Filament Nudger has the benefits of (1) reducing extruder stalls and also (2) it lets you install a new stick any time after the trailing end of a stick disappears into the 3Doodler. Without the Nudger, a new stick may fall out when the 3Doodler is tipped upward before the new stick is engaged, and this can be annoying.

Filament Nudger also works with longer 3mm filament

Filament Nudger also works with longer 3mm filament

With the Filament Nudger as a pre-feeder, Skip has been successfully using the same coiled filament that is used by MacGyvrBot (and other 3D printers). Warning: the use of such materials is not recommended by 3Doodler, and using any unauthorized materials will void the 3Doodler warranty!


Hinge pin



Create a hinge pin for the Grabber with small piece of filament, and put button heads on the pin with the 3Doodler.




2 Zip-tie Frame



Attach the Frame to the 3Doodler with a zip-tie.





3 Insert Skewers




Cut (2) 1/8 inch bamboo skewers to 7 inch lengths and insert them into the Frame (drilling out the holes if they are too tight, locking them in with small nails if they are too loose).




4 Insert Grabber



Insert the Grabber onto the filament and skewers as shown.






5 Insert Filament Guide




Insert Filament Guide over skewers and filament as shown (drilling out the holes if they are too tight, locking them in with small nails if they are too loose).




6 Hook rubber bands




Hook rubber bands over Grabber and attach them to Frame as shown.




 In our next post we will show how to use the 3Doodler to hack up accessories for itself!

Stay tuned!


from on May 9th, 2014Comments0 Comments