Day 3 brings trouble on the horizon.  The rack and pinion system for the “squeezer” is not working as planned, and it looks like a great disassemble and redesign is in order.  Preliminary testing does not look good: we think we’d better put syrup in it and really test it out to make sure we know exactly what isn’t working.

Testing Squeezer v 1.0

As you can see, some chocolate sauce does come out.  However, it’s not very much and the gears slide along the rack instead of pressing securely against the bottle.  Conclusion: The LEGO gears sadly are not made to transfer power—the linear motion squeezer didn’t have enough force to actually squeeze the chocolate syrup out of the bottle.

Next step: Disassembling and going back to an upgrade of the original plan: attaching angled pieces onto axles going directly into the motors.  This not only conserves pieces, but also doesn’t use any gearing and is much simpler.

Iteration #2....

This one didn’t really do its job… It’s not squeezing….

So we made some alterations.  Unfortunately, this resulted in a terrifying moment: Things fall apart…..

Finally: 1:25 pm

After many rebuilds, we finally have a working “Choco-Squeezer!”

A close up of the final product

It works!

Here is a photo of the code we wrote for the Choco-Squeezer in LabVIEW 2010 for LEGO Mindstorms:

It is fairly straightforward, and mostly based on the time it takes to complete each movement.  The initialization of the process and the squeezing motion are both started by a touch sensor (the pressing of a button).  If you are looking for some help learning how to use LabVIEW 2010 for LEGO Mindstorms, check out this great collection of examples we pulled together last week: http://legoengineering.com/library/cat_view/28-code/164-labview-for-lego-mindstorms.html .

Next up: Creating the Sprinkle Station

While brainstorming ideas for the sprinkle station, we thought it would be a good idea to combine it with the cherry station, since they are a similar dumping motion.  It would not be difficult to put them both on one station–one NXT, one tower/base…it just seems like a good plan.


This was our initial plan:

After building one side, it became clear to us that the design was not sturdy enough to support the motor and the heavy sprinkle container in the position we wanted it.  We changed tactics and are now implementing a similar design as the first part of the Choco-Squeeze.

4:04 pm

The primitive sprinkler prototype is complete! The structure is pretty shakey, but once we add the cherry mechanism on the other side we will support the whole thing.

Sprinkler v1.0

Day 3 Google Searches:

  • Robots ice cream (I forget what we were looking for, but this came up:  http://www.robotsandicecream.com/… whaat?)

Day 3 Conclusions:

  • LEGO motors are pretty weak.  LEGO gears are even weaker.
  • Most of the time, your first instinct about a design is spot-on, even if it seems “too simple.”  Better simple and functioning than overly complicated.
  • Don’t do something new just for the sake of doing something new.  For our sprinkler, we originally wanted to do something different (aka orienting the motors perpendicular to the way they are in the Choco-Squeezer).  Turns out, the reason the Choco-Squeezer works is because that design really is the best.  Don’t fix something that ain’t broke!
  • Like sprinkles?  We hope so.

To Do for Day 4:

  • construct cherry dropping mechanism
  • stabilize structure
  • code, test structure
  • perfect it
  • begin thinking about whipped cream-er