Rotating Cake Tray with Lego

Anyone that decorates cakes knows how difficult is to stop frecuently to rotate the cake and continue to decorate it or apply the frosting. This rotating cake tray helps to easy the process of decoration. (11/5/2006)


Yummy cake My honey bun (A.k.a. sweet heart, mamasota, dulce) likes to make cakes but the hard part of it is when is time to decorate it. Applying the frosting and icing can be back-breaking work.


As I don't have any knowledge about cakes, I decide to help her in any other way: Creating an automatic rotating cake tray. She told me she already have a tray but is difficult to use because it doesn't stop by itself and can move while the cake is being decorated.


I took my Lego Mindstorm box, I removed the dust and started to create an automatic tray rotator. The operation is simple: Just turn it on and the tray will rotate by itself slowly. Later, I got the idea to put a pedal and change the program to turn the tray if the pedal is activated.


Here are the photos of the cake tray rotator:


lego cake tray rotator lego mindstorm cake tray rotator


How it works:


detail of the cake tray rotator A simple motor rotates two tires and makes the tray to rotate. The speed of the rotation is programmed on the RCX. As the RCX can handle up to 5 programs, easily can have 5 functions:


  • Cake display: Rotates the cake slowly for decoration or display.
  • Cake Decorator: Rotates the tray slowly while the pedal is activated.
  • Cake decorator II: Rotates the tray slowly in one direction and changes direction when the pedal is activated.
  • dual-speed rotator II: Rotates in one direction and increases the speed when the pedal is activated.
  • Multi-speed tray rotator: Increases the speed every time when the pedal is activated, up to five speeds.


    There is a lot of possibilities for this application, even can be used to display cupcakes or any other items, I can't say how many applications can have... Right now I'm thinking to add a light sensor and use it as solar tracker for solar cells.


    Anyway, this proyect have three parts: The rotator, the stand and the pedal (The RCX is already well known, so I will not explain it). The right photo shows the rotator and stand. It uses four rubber wheels. Those wheels can't rotate as it have a lock mechanism.


    It also have additional supports to avoid bending the plastic parts. As the cake can weight up to 10 Lb, I need to be sure there is no parts that can break. Lego parts are expensive.


    Basically, the only fuction of the stand mechanism is to avoid the tray to slip while it is being rotated.


    Here are some photos showing the details:



    The "brake" mechanism


    how the rotator is attached.


    The rotator:


    Just the motor, driving two gears and the rubber tire attached on it.


    The gears are attached only by a few parts, easy to assemble.



    The Pedal or foot switch:


    The switch is activated when pressure is applied to this box. Two gray blocks pushes the switch. It have two axles to avoid excessive pressure on the witch.


    Here is the detail inside of the pedal. The switch is mounted vertically.


    The switch desn't move because an axle and two beans (or connector pegs?) keeps it vertical.


    Another photo showing the switch inside the pedal.


    It looks simple but is kind of neat. I wish I can have more lego parts and create a complete machine that rotates and decorates the cake using a simple program on the RCX, in that way, decorating cakes will be so cool and easy!


    My assistant: "El gato delincuente" activating the cake-tray rotator.



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