Hi! I am starting to make mechanical cakes and i need to make robots (which are hidden under the cake board in a box or sometimes even partly concealed in the cake)
My dialemma is this...I have never built a robot before...and i have spent weeks researching on the net trying to find out what equipment i need am i am completely bamboozled.
So to start off with I will tell you what i need my cake to do..
the head of a crocoldile makes the shape of the cake. The lower jaw opens and out pops captain hook! Whilst the crocodiles mouth is closing i need sound "tick tock" and for hook to go bac inside the mouth and jaw to close. When his mouth opens and hook pops out I need him to say "smeeeeeeeeeee!!"
So far I have come up with a dc motor with a big cog of which is attached a rod and support mount. as the cog spins the stick moves up and down but i feel i will have problems with this as i cant control the speed. My guessing is the weight of the fondant figure will slow down the motor?? either that or hook will shoot off to neverland. This cake is for my sons birthday in march if this is a success then i will continue to make more.
What kind of mother board do i need and do i need a picaxe28. or if you have a simple solution i can build i'll be most grateful :)
ok i have now established that i need an actuator of some sort. can someone tell me if i need to program it or will it automatically go up and down by itself?
if it does need programming can anyone tell me the easiest method and what i will need?
BTW im in sunny england UK lol so guess you guys are all in deep slumber as i wrote this! haha xx
Alright, I want to make sure I have this straight.
You need to open and close a jaw, move a figurine forward and backward, and, trigger a couple of sounds.
Knowing how much mass you will be moving will be important, so, you can figure out how much electrical power your motor will require. Motors have two important ratings with respect to being controlled; voltage and current(Amps). A PICAXE board that contains a motor driver may suffice, but, if the motor is too power (volts * Amps) hungry, the motor driver chips that can be placed in the board might not be able to drive the motor. Bottom line, for the moment you need to find out how much power your motor will require to move the jaw. Remember, torque is measured force/distance. You can not simply decide the jaw has a mass of 500g and find a motor that can move that mass. You will need to fiind a motor that can move the mass that covers the same shape as the jaw will be. I hope I am making sense. I just awoke from my slumber.
Once you have the information about the motor, the rest should be fairly straight forward. I would suggest a servo to move Captain Hook, and, an MP3 board for the sounds. Speaking just microcontroller pins. You will require a minimum of two pins to drive the motor at a controlled speed, but, if you have a spare 3 pins can be used and save an extra bit of hardware. The servo will require a single pin from the microcontroller, and, enough power to move, maybe you can connect to the motor power? The MP3 board will require two pins as I understand, if you get the correct board.
Just so we are straight, the servo I am suggesting would be a standard sized (example) servo rather than a 9g servo like some of the robots around here use. The MP3 board (example) may or may not need an amplifier to be useful.
Thank you so much for your reply sorry its taken me a while i’ve had so much on but now back to concentrating on the task in hand! I can get hold of the servo no probs but when you mention “board” i know its a mother board but i havent the foggiest about what type (if there is one or if they are generic) to get?
I did build a little robot today with a dc motor and a worm gear but the speed was just to fast so i tried a bigger gear >:/ still the same problem! I even tried it with different weights and after 75grams the little bugger gave up on me haha.
I need to control the speed of the motor is that what the servo will do? captain hook will be made up of about 50grams of sugarpaste and as for the jaw it will be on a hinge basis (me thinks to makeit easier) so as captain hook rises he simply pushes open the lower jaw. (the top jaw will be stationery) and when he descends i was thinking maybe a lever which hook will push down on to close it or some string?
I am in desperate need of your assistance as my sons birthday is on march 25th and i need to get something built soon as!
If i get hold of the servo and the mp3 thingy can you tell me exactly what else i will need i.e what sort of wires connectors etc…
hell even if you build one and send it to me i’d pay you! xx
One question I asked, that seems to have gotten lost.
How long, and how much mass do you expect the upper jaw to have? This answer is rather important, as it will contribute to knowing how much power will be required. Pushing Capt. Hook back and forth on a slide won’t require much.
hello everyone thanks for your replies! I have made a quick frame for the jaw using a pringles tube! This will be strong enough to hold the weight of the cake on upper jaw and will be strong enough to support icing on lower jaw. I have attached some piccies for you.
Right numbers…the “jaw” stands at 22cm when it is standing and is 8cm wide. I have quickly put on some fondant icing to get an approximate weight of the lower jaw (as the upper jaw will be stationary) The lower jaw weighs 140grams but will hold 150 grams once completed as it will have further decortations on it. I have shown a few pics so you can see (dont worry this fondant is only for calculation purposes i will take it off and start again once i am ready to make the cake so will be finished to a high standard )
Captain hook will stand at 14cm tall and no mare than 6cm wide he will not weigh more than 50grams.
Dan asked that I make note of what was discussed in the shoutbox
You decided to make the attempt to use PICAXE. I suggested this board and you would need to purchase the programming cable, a servo (or two?), batteries, and, a PICAXE 08m2. I might suggest you purchase a couple red LEDs and 470 ohm resistors. Just so you can get a feel for what you are doing with this little chip. Also, you could/can use the LEDs to help you debug the program that you finally write to make the servo(s) move. There is a thought, that you may be able to use a single servo to open the mouth, and, move Captain Hook. It might help the servo move easier.
To go along with what OddBot mentioned with respect to you getting in deep ( ), I thought to myself, I bet they have a hackerspace you can go to and get some assistance with this. It turns out they do. Birmingham Hack Space seems to be in the planning stages. There is a group of people actively meeting and sharing help/ideas. I am sure you will find a decent crew willing to help as they can.
