Trick with treats, for Halloween this year I decided not to hand out candy. Instead I decided to launch candy at high speed at kids. This plan came about merely 2 days before Halloween and was executed with materials scavenger from the bone yard at LVL1 Hackerspace. It was a lot of fun and I am happy with how it turned out but with such a short time frame and the hack job it is I had to leave out and things I will do another way next time. I will try to cover all of them in this instructable.
The propulsion system inside of the pumpkin is two fans that have had their blades replaced with fabric disk. The candy is funneled into the spinning disk then shot out of the mouth. It works the same way tennis ball or baseball launchers work.
Step 1: Materials
*2 small fans
*Glue (I used hot)
*Nuts and bolts or screws
*Pumpkin carving knife
*Saw (metal if your fans are metal)
Step 2: Fans and Pumpkins
Fan selection is important. you want something with the power to throw your candy far but if you get to large of a fan it will make it hard to find a pumpkin that it will fit inside of. If you are scavenging like I was you will more than likely be picking the fans out then trying to find a pumpkin that you can fit them in. With a 13' span over both of them finding a pumpkin that would fold them the night before Halloween was not an easy task.
The fans that I used was 110v AC fan. They were more than likely used for cooling in a consumer appliance. I used some cut electrical cords that I had to add plugs to them so that I could run them right off of main power.
WARNING: If you wire a fan yourself and plan on plugging it into the wall make sure you know what you are doing and that the fan can handle it. It is a dangerous act and should not be done lightly.
Step 3: Preparing the Fans
If you are using fan you will need to do some prep work other than just wiring them up. First you will need to remove the blades as we don't want to shred the candy. You will also need to remove some of the housing around the fan and its blades. For most small fans a Dremel tool should take care of this. The ones I used had a somewhat thick metal housing that I had to cut off with a more powerful tool.
Step 4: Cutting Out the Rings for the Flaps
After you get it down to a bladeless fan with half of the cage removed you can make the new blades for it. I went with fleece as I just had it laying around but it ended up working very nicely. I did not have to worry about sticking my hand in it as it was so soft. Using your fan you will trace the inside and the outside of the disk. Cut out a few rings. I ended up with 5 on my fans.
Step 5: Gluing the Flaps On
After you have your rings you will want to glue them onto the center of the fan. The part you glue to should spin itself. when the fan is on. You will want to glue just one in to start with. Stretchy material will stretch out do to the centrifugal force and because of that after you turn it on it will start to rub on the parts of the housing that are left. with just one ring glued on start to cut it down a little at a time till it no longer rubs on the sides.
After you have one to the right size the rest will go much faster.
Step 6: Positioning the Two Wheels
To get the most power out of the two wheel set up we overlapped the wheels just a little bit. After finding a good distance for power for the candy size you are using attach it to a board with the screws or nut and bolts you have.
My fans were not the same height when one of them was turned upside down so we needed to stack some scrap wood under it. You may also find that when you get them in the right place that some of your candy is two short. If you find that it is going under the blades when you push it into the fan just build a small shelf for it to rest on. It will not need to go all the way under the blades as they will pick it up and do the rest for you.
Step 7: Loading Tube
I would have liked to add a hopper onto the pumpkin but do to time we ended up just installing a PVC pipe that we dropped candy down into. Getting the pipe just right is an art. Too high of an angel and it will not call into the blades or it will fall on top of them decreasing power. Too shallow on the candy will not fall out of the tube or if so it may not reach the blades.
Step 8: Install and Carve Your Pumpkin
If your pumpkin is the right size you should be able to cut the back out of it rather than the top and slide it in. As you can see with ours we had to cut it in the middle to fit it in. Take care when cutting out the mouth that the candy will be able to get out of it.
Step 9: What I Would Change
There would be a few things I will be changing next year. Both from lessons learned and things I did not have time to implement.
User smaller fans: I would like to use smaller fans to start with.
Build a hopper: I want to be able to remotely release candy into the pumpkin so that I can have it be more of a robot pumpkin.
Add motion detectors: I would like the pumpkin to automatically detect people and shoot the candy at them. Using open CV or something of the sort.
Install a webcam: If I am already using a camera for targeting I would want to be able to stream the pumpkin as it shoots candy at kids.
Pivoting action on one fan: When you pivot one of the fan it changes the direction the candy moves out. adding a controllable pivot would allow shooting candy in a targeted way.