Family Friday at RMSC

Interlock brought five demonstrations to our table at the Rochester Museum & Science Center Friday, July 19, 2013.

This was noon to 4 for the Make It! installment of their summer Family Fridays series.

From left to right, we see the MacGyverbot Printrbot LC generously lent for this demonstration but often seen in operation at Interlock, the Interlock Huxley RepRapPro 3D printer, a blue and white lunch-sized slow cooker keeping some Polycaprolactone (PCL) hand-moldable and 3D-printable thermoplastic (previously) warm and ready to try for free-form molding, the shoebox regatta demonstration (with special guest Mr. Jaws!), and at the far edge, a solderless breadboard with a temperature comparator demonstration featuring two LM35 temperature sensors picked up recently from College Home Hardware in Toronto.

Interlock's table at RMSC

Interlock table at RMSC Family Friday

We shared that portion of the first floor with some folks from Greater Rochester Robotics, who brought the robot from their most recent FIRST Robotics Competition season, Ultimate Ascent. They were letting visitors move the robot around the floor and occasionally launch a plastic flying disk or two.

It wasn’t quite the battle of the bots, but a couple of times the ‘bot got up a good head start and whacked into the front of our table, sloshing around the water in the PCL crock and the regatta box. Midway through, such a collision might have had a role to play in loosening up the Huxley’s X-axis drive gear (now since fixed), at which point we switched from printing in silver-gray PLA (polylactic acid) on the Huxley to printing in fluorescent yellow ABS (acrylonitrile/butadiene/styrene) on the MacGyverbot. This led us to discover that kids love them some bright plastic sharks.

GRR robot at RMSC

Greater Rochester Robotic’s 2013 FIRST robot wheels around the first floor of the Rochester Museum & Science Center.

from on July 23rd, 2013Comments0 Comments

11 Digit, 7 Segment Display

An early test result, showing text and millseconds since power-on.

About a year ago, I bought a few 11 digit, 7 segment red LED displays from Active Surplus up on Queen Street in Toronto. (Excellent store.  If you’re into hacking stuff at all, it’s well worth the trip. Look for the monkey on Queen street to find their entrance.)

This past week, I wasn’t sure what to do at Interlock on Tuesday night, but I had recently re-found these displays, so I figured I would finally get them working.  I hit Radio Shack to get a Seeed Studio Arduino Shield ($10 with a mess of components, probably the best deal in all of Radio Shack.)

The display with a header soldered on, and the shield with its assorted parts.

I was all set to figure out how to reverse-engineer the pinout on the bottom of the display; I googled for the LED module, and found specs on those, and then on a whim, decided to check on the entire module board, a Rohm LU-3011, and found the jackpot, this post about figuring out the pinout.  It suddenly became very easy to do this project.

The two key things gleaned from that above post, which I have mirrored here, are this table of enables for each of the 11 digits:

Digit 1 2 3 4 5 6 7 8 9 10 11
Pin 1 2 3 4 6 8 10 12 14 16 18

and this image, showing the pin mappings of the segments:

Mapping of the segments to the pins on the header.

The basic way these displays work is that all of the 7 segments (plus one decimal point) are all tied together to the pins specified above.  Then the anodes for each of the displays are broken out to the pins in the table above.  So to draw a ’7′, you would set all of the segments to LOW, except for pins 11, 19, and 7 which you set HIGH.  Then to turn on a specific digit, let’s say digit 11 (rightmost), you set the digit enable pin 18 to be an output, and set it LOW.  Set all of the other digit enables to be inputs (tri-state, not low or high), and only position 11 will show a “7″.  You repeat this for all of the 11 digits in the display, and you can display 11 full digits from just those 19 pins.

In my code (available below) I start at digit 1, and work down to digit 11, enabling each one, in turn, showing its segments, waiting 1 millisecond, then disable that digit, move on to the next one.

I soldered a pin header on the display, and built up a shield to plug it into.

All of the digit enables wired up.  The top ones are a bit messy. Sorry about that.

I wired it up such that the digit enables and segments are wired directly to IO lines on my Arduino.  This used all of the IO lines, minus the D13 pin, which has an on-board LED.

The code that I wrote (available below) lets you do arbitrary digits per character, so that i can do (primitive) alphanumerics, or do animation patterns, etc.  I also store the decimal point as a separate character going in to the display code, so “3.141″ is five ascii characters going in, but a flag is set on the ’3′ position saying that this digit should also display its decimal point, so it only consumes four digits in the display.

just testing out all of the segments and digits

For now, it displays a nice clock and some animations on my desk, but I plan on changing it around a little in the near future.  I want to use the D13 line as one of the segment enables (probably decimal point) and move the segment enables off of the Serial Receive line.  That way i will be able to control it via serial to display patterns, animations or text content.  Since the hardware serial port is hardwired to 0 and 1, and I will be using the TX line for the LED displays, I’ll have to instead use the Software Serial, with only its Receive line mapped to an IO pin, and its Transmit line mapped to junk. I’ve done this before and it works well.

The code for this project is available in my Geodesic Sphere github repository.

This post is also available on my personal project blog thing.

from on May 17th, 2013Comments0 Comments

Hackers are not the Bad Guys: Confessions of an Inventaholic.

Transcription of the talk given at BarCamp Rochester on April 20th, 2013, by Skip Meetze.

Hello.  My name is Skip.  I’m an inventaholic.  I am compelled to invent things for reasons that I can not control.  I would like to welcome you to Inventaholics Anonymous.

Over the past 40 years, I have followed a path familiar to many people with my affliction by accumulating as many patents as I could.  But with the help of my new friends at INTERLOCK, I have overcome those tendencies, and I am proud to say that I have moved on to the sober world of hackers and makers.  A world  known as the Open-Source Hardware Movement.

stepcounter 1

First Patent: The Stepcounter

In many ways, being an inventor has scarred my life.   In the early 1970s I squandered all the funds I could beg or borrow (at least I didn’t steal), and I blew it all on my first patent.  The Stepcounter was a research device to measure the activity levels of laboratory animals.  My wife wanted to make the down payment on a house.  Thanks to my addiction, we rented for 25 years before we bought our first house.

Kenneth Brown, the author of a book called Inventors at Work asked my old friend, the late Bob Gundlach an important question during an interview: “Is it better to be an inventor working for a large corporation, or would you rather be working on your own?”  I can relate to Bob’s answer: “Being an inventor on your own is a good way to go broke! Being an inventor in a corporation is a very fortunate happenstance.”

But even within a corporation you run into the Not Invented Here Syndrome.  If you offer a solution to improve a product that is outside of your assigned responsibilities, you will probably be rebuked with something like “No thanks. I’ve got my own ideas and I know what I’m doing.  Go work on your own assignment.”

vue iPad in comfort


I graduated from Xerox a few years ago and in 2010, my friend Ken and I invented a stand for iPads that we called the vue-stand.  It would hold your iPad at a comfortable eye-level.  As a human factors engineer I have spent decades designing easy-to-use products, and I thought that we were onto something.  After we spent thousands of dollars to do a pilot run at manufacturing and did a little test market, I couldn’t help remembering Bob’s words of wisdom.  People didn’t buy the vue for reasons we now understand.  We decided not to keep throwing money at trying to market a dead horse, so I bought out Ken’s interest in our company, and I continue selling off my inventory online without promotion.  That inventory will cut my losses, but it will not cover my investment.

Last summer something happened that changed my life:  A couple of guys from this Hackerspace called INTERLOCK Rochester gave a talk at AppleCIDER, a local Apple Computer Users Group.  They demonstrated a little desktop 3D printer that they had built themselves.  I was blown away.

I knew about Stereolithography and CAD (Computer-aided design).  Xerox engineers had made rapid prototypes using that technology for decades.  But specialist operated those machines, and they had talent and training that I didn’t have.  Furthermore, the machines cost more money than an individual could afford.

Now, people are building these little machines that can even build parts to replicate themselves.  And people are sharing their designs and discoveries for other people to build upon.  The source code for anything built on these little industrial robots can be shared online at a site called

They call the shared technology RepRap for replicating rapid prototyping.  The designs are evolving unbelievably fast because people are sharing with each other!  What a sobering thought!

I don’t plan to get any more patents.  Now I have a reprap machine, and I have joined the people who share ideas in a Hackerspace.

I used to think of hackers as being the bad guys who stole identities and maliciously created computer viruses and things like that.  Now it has come to mean people who take an existing good idea and hack on it to make it better.


iPad on a HandleStand

For instance, I have hacked-up an iPad accessory that I call the HandleStand.  I took a protective iPad case that I bought on Amazon for $8 and hacked it.  I drilled two holes and attached a pair of hinged handles to it with screws.  The case I chose also allows me to attach a Keyboard that protects the front of my iPad.

The handles open up to make a stand that allows the iPad to tilt at any angle.  Great for making videos or calling people on FaceTime with the iPad camera that can be pointed in any direction.  By the way, it also holds the iPad at a comfortable eye level just like the vue-stand.  But it is better for all these reasons.

Where can you buy this HandleStand and how much does it cost?  Sorry, but you can’t buy one.  You can get the source code from Thingiverse however, and if you can get access to a 3D printer you can make your own!  You can even hack it to make a better one!

You don’t have a 3D printer?  Well come on over to INTERLOCK on any Tuesday or Thursday night and we will help you hack one up.

I must admit that getting these little printers to run is a bit tricky sometimes.  They are complex electronic devices that run on an open source micro-controller called Arduino.  The hardware and software are made from the contributions of many-many people, and instructions don’t necessarily keep up with the latest developments. A lot of things can go wrong, and Murphy’s law does apply.

But hackerspaces are springing up all around the world where people help each other with things like that.  So you should join the world of hardware hackers.  Free CAD software has gotten so easy to use now that even I could learn it.

Pretty soon most people will know how to design using CAD just like now most people can make Powerpoint presentations.  Perhaps it won’t be long before most people will have access to a 3D printer.  I built one from a kit for a little over $500.  Or you can get a MakerBot already assembled for $2000.

I no longer spend a lot of money trying to sell inventions, I give them away and save a lot of money.  My designs can no longer be stolen from me.  I’m publishing the source codes on Thingiverse and I am happy that people are downloading them for free.

People tell me that I’m missing an opportunity to make money on my inventions… I don’t care.  I’m an inventaholic.


from on April 21st, 2013Comments0 Comments