After returning from my trip to Qatar for the Word Robot Olympiad, I was super psyched to build another LEGO Mindstorms machine. Kristal suggested that we build a cookie icing machine for the upcoming holiday season, and so, we present to you, the EV Icer!
I have put together building instructions for the EV Icer, along with the program file for running it, but be sure to read the operation notes below! The icing results can vary drastically depending on many factors. When everything goes according to plan it actually works quite well. All of the cookies in the picture at the end of the post were iced using the machine. To build the EV Icer you only need the LEGO Mindstorms retail set number 31313.
The motors should be connected to the ports as follows:
Port A – the medium motor for the cookie turntable
Port B – the large motor for the squeeze roller
Port C – the large motor that pushes and pulls the turntable assembly
The most important factor to successfully icing a cookie is the consistency of the icing. If it is too runny you will get a blobby mess. If it is too thick you won’t get a complete design. It’s hard to describe the ideal consistency, but it’s probably about the same as you would want if you were icing the cookies by hand. You may have to experiment to find the right balance. Don’t expect it to work perfectly the first time you try it.
You will probably get icing everywhere, especially if it is too runny. Be sure to adjust the height of the ‘ice stopper’ so that it blocks the end of the icing tip when it’s not icing. For smooth operation of the squeeze roller it is best to fold the sides of the icing bag in on itself as you drape it over the squeeze plate, before securing it in the back.
We are using a Wilton brand decorating tip (#4 Round) with a Wilton brand Coupler, which fits snugly in the bracket I have designed (see picture below). I don’t know if other brands of icing tips/couplers are much different, but if they are you will need to improvise to keep the icing tip secure. We are just using a generic icing bag.
The height of the icing tip should be adjusted (by sliding the entire squeeze roller/plate assembly up or down) so that it is just above the top of the cookie.
The patterns are designed to work with cookies that are 9 LEGO studs in diameter. Any larger and the cookie will get caught up in the frame. If they are much smaller the icing will be placed off the edge of the cookie.
Feel free to delve into the program file to adjust some of the variables. Manually adjusting the power applied to the motors is one way to accommodate icing of different consistencies.