Stirling Engine

I decided to create a small Stirling Engine. This is just the first to see some of the simpler complications of a Stirling Engine design. I started by making a gamma style engine. It will be composed of 2 cylinders, a heat sink, and a crank shaft. The cylinders will be made from copper because copper transfers heat well and it was readily available as scrap from school. The design was made on Inventor.

I have taken a propane torch and some solder and turned a sheet of copper into a hot cylinder, and a displacer piston.

The heat sink has had a hole drilled out of it with very large drill bits. The final hole was 1-5/8".

The next step would be to place the 1-1/2" copper tube, and attach all the copper fittings which would be bought at a store.

Bio Inspired Robot

Bio Inspired Robot

The last project for my MMAE 232 class was to make a bio inspired robot. The requirements are as follows:

1) Autonomously travels 4.9m on the designed track. The track will have a slight incline and decline on it. The change in height will be no more than 3.1 mm. Autonomous means you cannot touch it once you start it. After your robot completes its first 4.9m, you must pick it up and move it to the start line to complete its second trial.

2) The design must be bio inspired. 

3) Has the ability to be disassembled. No electronics can be glued down to anything.

We started by creating 2 sketches of a robot design, each inspired by a different animal. We chose the bear and the ostrich. In order to analyze this, we had to create a Hildebrand Gait Plot for each design, Identify the posture of each design, Identify the convex polygon for each of the gaits, Prove that the center of gravity is always within the polygon, and identify tourque requirements.

We chose to make the bear design. We used an Epilog 50W laser to cut out the frame from 1/4" MDF. After making our robot, we found out that it would not work because the center of gravity shifts outside of the polygon when the robot moves up the hill. We decided to modify the design by moving all servos inward toward the center of the frame. We created new legs that had a small contact surface. We modeled it after the sea turtle because it was meant to walk like one. 

We had issues with the battery packs coming loose. Videos looking at the walk of this robot can be found here. We were not able to tweak it in time to meet the deadline. 

Here is the link to the full report.

Trebuchet

Trebuchet

The next project after the Sustainable Chair Design was the Trebuchet. The goal of this project was to launch a rubber ball weighing 27 grams more than 12.5 meters. The material restrictions are as follows:

1. 10 pieces or less of 24" x 18" x 1/4" MDF
2. 10 pieces or less of 24" x 18" x 1/8" MDF
3. 1/4" acrylic rod
4. Wood screws
5. Wood glue
6. Rope or string of our choice
7. Fabric of our choice

The difference between a catapult and a trebuchet is simple.

Catapults are any device that throws an object, although it commonly refers to the medieval siege weapon. Trebuchets are a TYPE of catapult, using gravity (with a counterweight) or traction (men pulling down), to propel the arm and often employing a sling at the end of the arm for greater distance. This is different from other catapults in that it doesn't use built up tension for it's throwing force. 

We made a quick sketch of the trebuchet. It was composed of 2 main pillars, an axle, a release mechanism, an arm, a counterweight, and ribs made for balancing. 

A crucial part of this trebuchet was the computerized calculations used to see if our design was optimized. What I mean by this is that the length of the arm to the pivot, the length of the sling ,etc We were given Matlab scripts to modify our design. The Matlab scripts were modified based on the following diagram.

We changed the values of L, l, n, and r. As a result of the scripts, we had an ourput of a general imae of the trebuchet, distance graph, and a distance vs l vs L graph.

The max distance was predicted to be about 26 meters. This varied largely from our actual results because this design does not account for many things such as friction, air resistance, and wind. We went ahead and created a design on Autodesk Inventor for our trebuchet. 

Our next task was to make a release mechanism. We decided to make a hook release mechanism. We used simple force and moment equations in order to create an analysis of the release mechanism. The mechanism will be powered by a 250 N*mm servo.

After we analyzed these components, we created the actual trebuchet. We used an Epilog Laser Cutter 50W. We cut out each piece and used wood glue to put them all together.

After finishing our design, we attached the servo to a battery pack for power and an Arduino Mega 2560.

We ended up launching the ball 16.7 meters. Here is the video.

Frame Making

Frame making
Yesterday, I created a frame for a bicycle seat using a hand wire bender. This involves using the simple ideas of torque and reaction forces to create bends in 1/4" x 6' hot rolled steel wire. The end product was is shown in the pictures below.

I first started to practice with this device. As you can see, s simple stock bar of steel has been bent just to see how it would look.

 Next, I tried bending a bicycle frame from a pieces of 3/16" chromed steel. I managed to get about a quarter of the whole frame done. This helped more toward bending in 3 planes. The pictures below show the seat I was using as a reference.
Eventually, I managed to use the 1/4" steel wire. I created a seat frame that allows an outer perimiter as well as an inner support.

This is the final product. I used about 5 feet of the wire to make this. The break will have to be welded together. I believe this is pretty good for my first time using this device.

I am hoping to make a video at 10x speed to show the process of making a more complex figure.

Sustainable Chair Design

Sustainable Chair Design (Jan 12-31, 2015)

For my MMAE 232 class (Innovation for Design), I had to create a chair with the following parameters. This meant starting from sketches of prototypes to the final technical report.

Let's start on the sketches:

First, my partner and I created 3 prototype sketches each. They are as follows.

 Each of these sketches have the lines of force drawn on them to show where the stress concentrations were and how to eliminate them. Using a pugh chart, We selected concept #3.
The next step was to use Autodesk Inventor to show what this would look like. I created the individual pieces and places all of them together. All this can be found on my technical report.

Ping Pong Paddle

Creating a Ping Pong Paddle
After Playing for about 2 years, I decided that I should upgrade from the cheaper paddles to a better one. I looked at paddles online and I couldn't decide what to get. I eventually thought of creating a paddle from scratch. Using Autodesk Inventor, I created an image that I will later use on a laser cutter to cut out the wooden section. Here is the image.

I am planning on cutting this out tomorrow. After which, I will use fiberglass, basswood, balsa wood, and a sheet of insulation to create the rest of the blade. This is just a prototype to see if my configuration of materials and choice of materials works. If it does, I will use better more expensive materials for my next model. (Carbon Fiber, Sorbothane, polyurethane, etc)

Update: After an attempt at making a composite board from bloodwood, carbon fiber, and balsa wood, we have run into some issues pertaining to the outcome of this composite. In order to make this composite, we layered the bloodwood on the outsides of the composite, balsa wood in the middle, and a layer of carbon fiber in between. (bloodwood-carbon-balsa-carbon-bloodwood-> 5 layers).

The issues that we ran into were significant enough to hinder the performance of the paddle considerably. The process that we used was layering thin sheets of balsa wood perpendicular so that the grains would cross, hindering warp in the soft wood. There was a small layer of wood glue keeping these pieces together. This was placed on top of wax paper and a large piece of plywood. The paper kept the glue from sticking to the plywood.
After this was done, and the glue had set, we removed the balsa composite and placed a piece of new wax paper and a piece of bloodwood. Then, we placed a layer of resin and carbon fiber to bond he two pieces. Lastly, we placed the balsa composite sheet onto the still uncured carbon fiber sheet so that can bond, then the next carbon fiber, and so on. Each sheet for the balsa was 2' x 6" x 1/32". The bloodwood sheet was 2' x 6" x 1/16". With the carbon fiber, the total thickness of the blade would come to a little under 1/4".
In order to make sure the composite did not have any gaps within itself, we placed another piece of plywood on top of the composite to evenly apply a pressure. This helped with releasing excess resin and air pockets.

The Problems: After using this method of compressing the composite between two wooden plates, the problems became evident very quickly. Once the  plates were removed, we noticed 2 problems. The first problem was that the pieces of carbon fiber and wood have shifted from the center slightly. The shift was only about a sixteenth of an inch, but the widest part of the paddle was 5.99... inches. The shift was too great and therefore the composite will not be used for the final product.
The second problem was that when we used clamps to compress the boards, we used too much force. As a result, the balsa in the middle became compressed. This means that the mechanical properties were altered. The bounce of the ball during the hit would be different. However, a different paddle can be made that is slightly smaller.

What We Learned: During this experience, we realized that we should have thought out the manufacturing process more. We could have done simple stress analysis calculations, and used a torque wrench in order to find how tight each clamp had to be. There could have been side guards in order to prevent the shift.

09-24-15
After taking some time off to focus on schoolwork, I have decided to try creating an experimental paddle. The plan is to create a 3D printed skeleton, fill it with foam in order to create more structure, and cover this skeleton with carbon fiber.

Update: I have created the skeleton which consists of the paddle outline and a mesh consisting of octagons and squares.

The 3D printing was done on an Airwolf 3D HD printer. The material was PLA plastic.

The next step was to fill this paddle with foam. Great Stuff insulation was used for this due to the small shapes.

The process was repeated in order to get a uniform fill.

This was the result after filling it further and sanding off the excess. When attempting to bend the piece, I noticed that the paddle structure was about 3 times more stiff than without the foam.

After making this structure, I decide to test one of the handle that I made. An earlier prototype looked like the following:

However, I ended up changing the design to make the ends wider and the middle wider and shallower. A CNC machine was used to carve out the handle from a piece of poplar.

This was just to test fit the grip and how well it handled the paddle. The final handle will be made out of a wood that might look slightly better.

Phone Screen Fix

Fixed my Phone screen. Has to take apart the entire phone. lots of little pieces needed to be disconnected.
Followed along with this video.
It looks really nice now, however my phone cant take a picture of its screen.
Good skill to have. I can be a professional phone screen fixer :) .