Automated Cereal Dispenser

This project was very fun to carry out and taught me lots. It has taken a very long time to transform this from concept to a physical project. I didn't make this project because I needed a cereal dispenser but rather I thought it could be a fun and challenging project. This is my first instructable but I have been making projects since I first learned to walk into my garage and hold a screwdriver. I was able to access my school facilities for this project and it was a great learning process. Even though I used high tech machinery this whole project could still be done with everyday tools if you had the patience and the creativity to think outside of the box. Without further ado, I hope you enjoy this project and please consider voting for it if it's in a contest. Please feel free to comment and let me know where I could improve.

1x Floorboard (app. 1m) or whatever wood you wish to use.

2x Acrylic sheets (1000x500x3mm0

1x stainless steel sheet

1x stainless steel rod (3mm diameter)

2x Hinges

1x Doorknob or handle

2x Small magnets.

You will also need a 9v battery, limit switch and Motor with a gear system.

Since I made this project out of what I had to hand, a lot of the supplies are miscellaneous and you just have to adjust the list to what you have.

When I started third year I decided I would like to further my knowledge and skills by learning how to use CAD (computer aided design) to design a project, I could then use advanced processes to make my project such as CAM (computer aided manufacture).

I asked my teacher to send me the link for the student version of Solidworks 2018. From here on I self taught myself how to use the software and after multiple hours of trial, errors and practice, I found it second nature to draw up most 3D models. The benefit of using CAD is that it allows you to preview what the design will look like in 3D before you make it. I decided to take my working drawings from this model instead of redrawing them because I put so much work and effort into my solidworks model.

After I had created my CAD model I needed to create a model for my project. I did this using styrofoam. I started to make this by printing out each face of the CAD model onto paper. I then glued these sheets onto the foam. Using a scalpel and the scrollsaw I was able to cut out these shapes. To make a right angle I cut two pieces at 45° to create a 90 degree angle. I used tape and hot glue to join these pieces together to get a clean joint.

I had to cut some extra pieces for support because the entire model was styrofoam and lacked the necessary strength. This model had limited functionality but I was happy with how it went. It dispensed cereal but could get clogged because it wasn't perfectly made.

I used Solidworks to create a 3D model of the base. This was my first time using Solidworks but after several attempts, I was able to successfully create the 3D model to the right dimensions and with the necessary features.

I started by drawing the shape in 2D on the top plane. This allowed me to set the dimensions of the shape and make sure the circle was centered and not to the left or right.

From this drawing, I was then able to extrude the selected parts 20mm. I selected everything except the outer rectangle. The area highlighted in yellow is the selected area and the preview of the extrude.

I then drew the hexagon on the extruded model. I set the dimensions of this shape so that it was also centered in its location.

I then selected the hexagon and used the feature extruded cut to remove 10mm of material. This would allow Part 2 - The Connecting Hexagonal Prism to insert into the removed section, strengthening the joint and reducing the chance of it breaking under the weight of a full cereal hopper.

Finally, I added a fillet to remove the pointy perimeter and replace it with a smooth curve. The fillet is outlined in blue in this picture below.

After I had created my model on Solidworks. I decided that I wanted to use computer aided manufacture (CAM) to make the base. I asked my technology teacher to show me how to use the CNC router.

The first step was to convert my file into an STL file. An STL (an abbreviation of "stereolithography") is a file format native to the stereolithography CAD software created by 3D Systems. STL has several after-the-fact backronyms such as "Standard Triangle Language" and "Standard Tessellation Language".

Once I had converted it into an STL file I then opened the file on the computer connected to the CNC router.

Once I had set up the CNC router I could then prepare my walnut floorboards. I first put them through the planer to bring the thickness down to 15mm. I then glued the four boards together and clamped them until the glue dried. Finally, I ran them through the planer once again.

I then began to finish the piece by sanding it with the belt sander and then hand sanding it. Finally, I used Danish oil to bring out the dark colour in the walnut wood.

The first step was to cut out a usable size piece from a sheet of red acrylic on the bandsaw. I then could mark out the six different rectangles, using a ruler and pen so I wouldn't mark the acrylic as a scribe would.

I then set up the bandsaw table with a 30° tilt on it. I used a 30° tilt because when I would join the two pieces it would create a 60° angle. I then set up the guide on the bandsaw to the right size to cut each piece. I then ran the marked out piece through the bandsaw flipping it with each cut to get alternate angles.

I then sanded the edges of each piece and did a test fit using sellotape. Once I was sure the fit was right, I wrapped tape along each edge so the glue won't come out and damage the outside surface. I glued each angle making sure to apply sufficient pressure for the liquid acrylic cement to create a good bond.
I then checked to make sure the fit was tight with the base.

I started by drawing each side on Coral draw. This meant that I could then send the files to the laser cutter in my school’s technology room. Alternatively, you could cut the pieces out manually. I simply had to set the laser to start from the centre and work from bottom to top. Then I configured the speed to 2.2 for acrylic and power 98. I then sent the file to the laser cutter. The last thing I had to do was mark a square on my piece large enough for all parts and then draw diagonals from each corner. The intersection was then in the centre and this is where I lined up the laser to start.

The first time it started laser cutting I had a problem where it started cutting several times over the same lines widening them and ruining the dimensions. Fortunately, I spotted this nearly immediately and quickly stopped the laser cutter. I had forgotten to set it to “hairline” in settings. Luckily I was able to use the same piece of acrylic by just shifting it to the left slightly. This time it went all successfully and I was able to then test fit it using tape and then glue it together using 90° clamps. I then measured and then glued on an axle hub on either side of the space left for the activation paddle to go in.

I started this part by taking measurements from my CAD model. I had to account for the bend on the plastic so when I converted it to an STL file, I had to add 5mm onto the drawing to account for it becoming 2 dimensional. I then added some text to the bottom so that people would know where to push. To do this I had to change the text to a different colour. I could then configure this colour to engrave instead of cutting all the way through by increasing the speed and reducing the power. Once the part was cut out I was then able to use the strip heater. If you don’t have access to a strip heater as many people wouldn't you could cut the sides off and cut a 30-degree angle and then glue it back on. I then placed the area I wanted to bend over the heat so that it would become hot and malleable. Once it had come to a sufficient temperature, I was able to bend it making sure that everything stayed straight and perpendicular.
I made sure the two sides were at the same angle. I was then able to measure where the axle hubs were to go on the back of it. I then glued these on. I then put an axle of 3mm through the axle hubs on the main compartment and the activation paddle, this made a pivot point so that when a person pushed their bowl against the activation paddle it would trigger the limit switch.
I then glued a limit switch on to the activation paddle using a limit switch mount. I then installed a piece of wood and a compression spring so that it would provide the right amount of mechanical resistance in order that the switch would be activated.

I first got a water bottle from my house. I then cut the bottom off it using tin snips as it gave the best cut on the curved section. I proceeded to make it flat by sanding the base in a circular motion on a piece of sandpaper. The next step was one of the most difficult throughout the project. I had to cut an opening for the cereal to enter into the dispenser and another hole for the cereal to exit. Using the tin snips I was able to cut the shape out roughly.

I then used double-sided tape to attach a piece of sandpaper to a piece of acrylic 40mm wide. This was the right length for the two sides, and for the top, I just moved it from left to right. Using this allowed me to make each side perfectly flat which would be important for the next step.

I quickly drew up four rectangles on the laser cutter that would fit perfectly. I then cut and glued these using liquid solvent cement.

I then joined the acrylic onto the bottle using liquid solvent cement. As the insides of these rectangles overlapped on the inside, I had to use the rotary Dremel, files and sandpaper to remove the material to make this flush. I then used steel wool on the inside to make it smooth.

I simply finished the bottom exit by just sanding it and no acrylic was required. I then glued this onto the main piece with more liquid solvent cement.

I started by measuring the angles and curves inside the bottle, using some maths I was then able to draw a rough cross-section of the bottle. I then cut this out on a piece of paper and after a few attempts, I was happy with the fit.

I then traced the outline onto some sheet metal. Using the tin snips and a hacksaw I was able to cut the shape out roughly. I then used files and sandpaper to create a snug fit that didn't have too much friction.

I then repeated this process. I then wanted the two parts to be perpendicular to each other so I cut a slot a quarter of the way down from the top of one with a width of 1 mm. I then cut a 3 mm slot from the bottom that went 20mm up the piece.

For the other, I cut a 3mm wide slot from the bottom with a length of 20mm. I then cut a 1mm slot up from the centre of the 3mm slot. This brought the total length of the slot to ¾ of the piece.

The first time I tried this, I went too far with the cuts damaging the integrity of the piece and causing it to bend over minimal force.

These two pieces then slotted together leaving a 3mm wide slot at the bottom. I then stuck a 3mm metal rod into this slot and used epoxy resin to secure it there. I then test fitted it again. Once I was happy with the fit, the dispenser paddle was completed.

I started the hopper by drawing it up on coral draw software. I was then able to laser cut each piece of see-through acrylic. I laser-cut seven rectangles and two octagons. I then cut the edges on each rectangular piece to 22.5° so that when two came together they made 45°.

I then placed all these rectangles around the octagon. This formed an octagonal prism that would be used as a hopper to store the cereal. The open side would be glued down to the dispenser. I still had a problem though. Since the bottom was flat any cereal would just sit on the bottom.

To solve this I used some maths to calculate the size and angle a piece would be needed to be cut at to sit flush against the wall at an angle. I then cut this piece and glued it in. I then attached a hinge and magnets to secure the door on the top. This door will be used to fill the hopper.