Today, we embark on an epic journey.  We begin quite possibly the coolest project either of us have ever done: designing, building, and programming an ice-cream sundae making robot.  Our materials of choice: LEGO NXTs.  We invite you to follow along as we keep track of our ideas, experiences, failures, and successes over the next few weeks.

To introduce ourselves, we are Jess and Tucker: working this summer as LEGO Engineering Fellows for the Tufts Center for Engineering Education and Outreach (http://ceeo.tufts.edu/).  Basically, we are discovering new, cool things to do with LEGOs and LabVIEW, and making sure other people can do them too!

Jess and Tucker: summer interns at the Tufts CEEO.

Day 1

Parts we want to include:

  • Pour hot fudge
  • Spray whipped cream
  • Sprinkle some sprinkles
  • Drop a cherry on top

Depending on how long and difficult those tasks turn out to be, we may add/subtract some along the way.  We’ll also be keeping track of everything that we Google search—for images, inspiration, and anything else.

There are a few things to think about before we get started:

  • We can either have all the functions happen in one station, or set up a conveyor-belt type of assembly line.
  • Ideally, we’d like to minimize the number of pieces used, in order to make the project accessible for as many people as possible to recreate.  This means hopefully no more than a couple NXT Bricks…it would also  be okay to have each “station” or part of the project require one kit.
  • We will be programming in LabVIEW 2010 for LEGO Mindstorms.  Final code will be posted at the end!
  • It would also be nice, at the end, to build the thing in Digital Designer (a LEGO CAD software), to have a parts list/building instructions.  We’ll see how feasible this actually is…
  • Tonight we will go shopping for ice-cream sundae making supplies!

First up, the hot fudge applicator.

Which type of bottle will be easier to manipulate?

In general we are partial to real hot fudge (jar) but to pour it well you have to heat it up…that’s a problem.  The odd shape of the chocolate syrup bottle could also make life difficult.  We’ll try to find a round squeezy bottle of real hot fudge that does not require heating up.


This one kit thing is going to be hard if we are building free-standing structures.


Ran out of rounded beams while building the hot fudge tower.


Which is better: a stationary, sturdy holder for the syrup bottle and an additional “squeezer” or one mechanism that doubles as a holder and a squeezer?

We can already tell the way to do this is build the individual stations.

Day 1 Google Searches:

  • hot fudge
  • chocolate syrup
  • cell phone tower
  • truss tower

Day 1 Conclusions:

  • Sadly, the 1 kit per part idea, while noble, is going to have to be discarded.  We simply need too many rounded beams (and connectors) to create a sturdy structure.  Maybe later in the project we can work on trimming some down, but for now, it’s not looking good.
  • This is looking like a very cool project with a much wider range than we originally thought.  Right now we are technically making the chocolate syrup robot, but in reality, we are creating a generalized “squeezer”.  This could have applications way beyond our ice cream sundae system.

Our first attempt at a "Squeezer Bot"


  • may need to eventually gear up the torque on the motors to actually squeeze out chocolate syrup.  Maybe create something on torque needed vs viscosity of liquid/strength of bottle you are trying to squeeze
  • definitely need to change grippers, ones on currently are just for show

To Do tomorrow:

  • Holder for bottle
  • Better “Squeezer” grips—test out a bunch, see which is most effective.
  • Aka “finish” squeezer bot. (1st iteration)