I like to carve pumpkins for Halloween(ironman, deathstar), but there are so many amazing carvings, that this year I needed something different. I decided to make a 3 sided, 3 level, arduino controlled rotating pumpkin. I believe that gives me 27 different pumpkin faces in one. So that seemed different enough for this year.
Step 1: Materials
If you want to make one of these here are the materials I used
Arduino Uno w/ external battery pack
4 AA battery holder
old printer cable with pins
Wood dowel 1"
3 - PVC 3 way T's
2 - servos regular (converted to continuous rotation)
1 - servo low profile (also converted)
3 - Lego pully pieces
Misc shop tools(drill, saw, screw driver,wire stripper,needle nose)
Step 2: Building the Center Spinner
This might not be the exact order I made this project. I actually made another one before completely redoing to this stronger version.
Begin by cutting the center dowel at least 12" or rough to the height of your pumpkin.
Cut the base plywood stand to 4"x4". Then drill a hole in the center that is the outside diameter of the pvc pipe.
Cut a piece of pcv to the same thickness as the base wood and insert. I put a strip of gorilla tape around it to make it a snug fit. Also cut three more pieces for spacers in the bottoms of the PVC T-joints to allow the wood to spin smoothly. Put the base on a flat surface and secure the dowel with three screws.
Next, carefully drill 1" holes in the dead center of each T-joint for the dowel to go through. Drop the first T-joint over the dowel and down to the base plate. Make sure it spins freely and sand as needed.
Cut six, two inch pvc pieces and six, 3 inch dowel pieces. Put them in each T-joint as seen in the picture. Drill and set small screws through the pvc and into wood. This will be adjusted later when inside the pumpkin to the right length.
Now trace the low profile server on the side of the base plate and cut out to fit. I notched the bottom to allow clearance for the wires. Don't forget to pre-drill pilot holes for the mounting screws.
To make the pulley attachments, carefully drill or cut a little bit from the center of the Lego piece so that the servo set screw will be able to reach the servo threads, but not go all of the way through. Drill two other holes on the sides and attach with short screws. They need to be short enough to not hit the servo. I didn't have short enough screws so I just sanded them down.
After you have the pulley wheel attached. Mark a line on the T-joint where the rubber band will go. I held a sharpie on the wheel and rotated the pvc to get the straightest line I could. Then using my band saw I notched out the mark wide enough for the rubber band to fit.
The second level;
I guess you could use low profile servers for them all, but I only had one and it didn't matter that much to use regular servos. Repeat the servo tracing/cutting/mounting and pulley setup as before. When setting the servo base to the dowel give yourself a little room between the bottom of the server and T-joint.
Repeat steps from level two.
When that is finished you will need to flip the spinner on it's side and mark the location of the servo wire on the center dowel. We will be cutting a channel in the dowel to run the servo wires down and out the bottom. Take it all apart and cut about 1/4" wide channel straight down the dowel and out the bottom. I used a dremel and hand chisel to do this. Be careful and always cut away from you.
Put two rubber bands around the base of each T-joint and reassemble the spinner. Feeding the servo wires through the T-joints and servo bases as needed. Make sure everything spins freely and no wires get hung up. (The second rubber band is there in case you snap the first one and don't want to take the whole thing apart to put another band on)
Step 3: Building the Controller
I've never used an Arduino before, so I had a little bit of a learning curve with this project. It's such a great device however, that with a little internet searching anyone can do it.
I probably bought the wrong potentiometers for this project but I didn't know what I needed so I go these. Simply drill three holes in your project box lid and install. There are plenty of instructables for how to use them so I won't go into details.
Install your on/off switch in a similar fashion. I salvaged mine from an old R/C toy.
The wire I found in my junk box was an 8 braided wire, but I needed nine. So I just wrapped one more around and cut them to about 20 inches. The pins soldered at each end were salvaged from an old printer connector(photo 2).
Roughly following samples online I wired up the three potentiometers and three servos to the bread board and Arduino. Using an external power supply of four AA batteries for the servos and 9V battery pack for the Arduino. I really wanted everything to fit in the project box. That is why my breadboard is spread out to allow the 9V to fit and still have room for the potentiometers. I can give you my Arduino code, but I think you would be better off learning how to do it yourself.
After a lot of soldering and a little double sided velcro tape to hold things in place the controller is finished.
I taped and drew some pictures next to each potentiometer, hopefully explaining how to work the pumpkinator.
Step 4: Cutting the Pumpkin
While experimenting with my first pumpkin. I realized I would never be able to cut it exactly straight or find a perfectly cylindrical pumpkin. So I have accepted the natural differences and moved on.
This step requires a dry erase marker, ruler and optionally a lazy susan. Hold the ruler next to the pumpkin and mark the height of each level. Evenly spacing out the eyes,nose and mouth sections, draw the straightest lines around that you can for each level.
Looking down from the top divide the pumpkin into thirds and mark guide lines down the sides of each face. Sketch your three sets of eyes,nose's and mouths and carefully cut them out. Here is a link to a good pumpkin carving website if you need ideas. I was so concerned with the spinning part that I just made simple faces. A classic face, funny face and angry face.
Using a jigsaw or knife, cut the top levels off and scoop the guts out. Scrape the sides a bit more than normal to try to reduce the weight.
Trace the base plate of the spinner onto the center of the pumpkins bottom. Cut out a square and cleaned things up as needed.
Cut the remaining levels and then preserve your pumpkin with a nice coating of cleaner with bleach.
Step 5: Assemply
Now put the spinner into the bottom section and secure it to a larger wooden base plate. You might need an additional spacer to make things fit. Also you will have to disconnect the servo wires to fee them up through the bottom, so mark your wires to help during reassembly.
Once it is secure, put your wires back together and cut a little section in the pumpkin base to keep them out of the way. Also cut a groove in the bottom of the pumpkin to feed the wires out to the control box so it can sit flat.
Next, lay the bottom mouth slice onto the bottom section and line up your guide lines. Extend the wooden telescoping arms from the T-joints to the edge of the slice. Try to find a spot that doesn't interfere with your design. Reset the set screws and using your best guess drill a pilot hold through the pumpkin and into the center of the dowel arm. Screw it in, but not too tight that you deform or go through the side of the pumpkin.
Repeat for the second and third levels.
The very top piece fit pretty well, I just dug out a little hole and set it on there. I was originally going to secure it to the dowel, but it seemed fine spinning with the eyes section.
Step 6: Finished (for This Year...)
I wanted to run some LED's from the arduino that would flicker and change color, but ran out of time. I simply put some store bought lights in the base and made a little video before I missed Halloween.
As you can see from the video things didn't work out completely as planned. I need to 3d print some gears or get a chain drive for it to spin the way I wanted. However, I should have no problem getting it working for next year.
It's still fun to spin it around by hand and get all the different face combinations. I'm happy with what I made and I hope you like my pumpk-inator.