Signature Clock

The objective is to design two cases for the design suite brass clocks that will showcase the mechanical engineering department as well as the exquisiteness of the W.R Smith design.

Final Project
Our original intentions were to build a display case that would be put into the wall that separates the entrance to Gauss Johnson and the machine shop. Unfortunately we ran into some snags and complications with facilities. We eventually got around that only to be stalled by budgeting issues. Once this was discovered our last option was to design and build a stand alone case that would represent all of our progress. These cases have all of the intended electronics that would go into the final product, all that is needed is permission and a transfer of electrical equipment from the prototype.

Next semester this project will be picked up by the IEW students and they will have the task of gaining access to the wall and transferring the equipment over.

Background
The objective of team Anchored Engagements is to design, build, and manufacture two enclosures for the two signature clocks of the Mechanical Engineering Department. These two enclosures should serve to compliment the W.R. Smith designed clocks, educate members of the university on a variety of engineering subjects such as: design, manufacturing, kinematics, kinemetrics, and acoustics. They should inspire perspective students to pursue a career in the Mechanical Engineering and show off what this department is capable of.The inspiration for this project was derived from the master clockmaker, W.R. Smith. He holds a Bachelor's of Science in Mechanical Engineering from the University of Tennessee in Knoxville. Mr. Smith got his start in the engineering field at the age of just 10 during the Roosevelt's REA(Rural Electrification Association) program. By age 14, he was fixing watches and learning all he could about the latest problems and their solutions. It wasn't until 1995 that one of our two clocks was invented, the Wall Clock. This clock was in W.R. Smith's works for several years before he published his works. Years later our second clock made and appearance, The Grasshopper Clock.

Keeping Time
The simple answer to this question is no. All clocks, to some degree, have imperfections and variations caused by a small flaw in the design or manufacture of the clock. Some mechanical clocks are manufactured to extremely high tolerances and are capable of keeping near perfect time. The problem begins in the fact that it is made up of a mechanical system. Effects of age, corrosion, atmospheric conditions, dust, fatigue, and even the local force due to gravity can affect the run rate of a clock. The largest of these is the effect of atmospheric conditions, mainly temperature.

All mechanical clocks have some form of an escapement, or gate, that allows the clock to advance in an organized fashion that is controlled by a pendulum of some form. From physics we know that the beat of a pendulum is not determined by the weight but by the length measured from the pivot point to center of gravity of the pendulum. This is only true for a standard pendulum, the equation gets more complicated if there is a compound pendulum at play like in our grasshopper clock, see Compound Pendulum. If there is a change in temperature that varies from the point at which the clock was calibrated at, the pendulum could grow or shrink due to thermal expansion. There is a way around this, see the Gridiron Pendulum. A temperature compensated pendulum clock with a weight drop system due to gravity can be very accurate if machined correctly. Our pendulum clock can easily achieve +/- 1 minute over the course of its one week winding period. The grasshopper clock is a different story however. The grasshopper clock uses a grasshopper escapement, named for its grasshopper like legs that alternate between the two gears. See Grasshopper Escapement. In addition to the regular manufacturing defects that may come in the way of making a perfect clock, the grasshopper clock as two more notable things that get in the way. The first deals with the escapement design itself. Because the escapement and the pendulum are attached directly and is acting on both side of the swing at the same time, the motion of the escapement interferes with the pendulums natural motion as a harmonic oscillator. This effect makes the clock motion extremely hard to model or predict from a mathematical point of view.

A small increase in torque applied to the gear train can have major effects in the timing of the pendulum since the forces transmitted by the escapement is so large that it negates the natural forces that exist due to the motion of the pendulum. The second factor that is against our grasshopper clock is that, unlike its wall clock sister that uses a weight, it uses a torsion spring to drive its motion. A property that exists with torsion springs is that they do not have a constant torque or even a linear torque as a function of its wind angle, even though as engineers we may model them as such for simplistic sake. A torsion spring generally has a relatively flat torque curve as it is loaded, but as the winds increases the change in torque becomes less and less. In order to deliver a constant torque to a clock system we use a fusee to convert the torque to a linear fashion. A fusee is nothing more than a barrel that the winding wire wraps around that has a changing diameter. As the winding on the torsion spring becomes greater, the diameter of the fusee becomes larger to accommodate the lower force that is being delivered to it. It is analogous to changing from high to low gear in a vehicle. See Fusee. Interestingly, most mechanical wrist and pocket watches use a torsional spring for the power delivery for the drive mechanism, but also use a torsion spring coupled with a small flywheel used as the pendulum. See Torsional Oscillators.

Because of the factors that are against the grasshopper clock being a highly accurate clock we can tune it to have an average correct time over the course of its wind cycle, however, throughout the week it may vary as the speed increases and decreases due to the difference in torque since our fusee is not quite the correct shape. Also, due to a slight inconsistency in the manufacture of the clock, one of the gear meshes has a slight eccentricity which causes it to cycle through periods of fast periods followed by slow periods. Because the beat of the clock can be measured and recorded over long periods of time, this variation shows up as an overlying sine wave for period times. This cycle happens every 12 minutes and varies the period by 4 beats per minute. A cycle time of 12 minutes can be traced back to the rotation time of one of the gear meshes that contains the eccentricity. Since this variation is regular and repeating, the time ultimately averages out and settles to the required 72 beats per minute that the clock requires to keep accurate time.

Skeleton Clock

 * The Skeleton Clock of the "Wall Clock" is driven by a weight that drops over a one week period. While the weight is dropping, it is driving a pulley system that turns all of the gears that eventually get all the way to the engagement. This is where the clock connects to the pendulum which swings back and forth. So as the weight is dropping, the engagement is giving a slight push to the pendulum so it can keep swinging. So if the engagement is not calibrated correctly, then the pendulum will not get the push it needs to keep running.

Grasshopper Clock

 * The Grasshopper Clock is not run on a weight dropping but on a torsional spring that is in the barrel at the bottom of the clock. Once this clock has been wound it will run for one week. From the torsional spring in the bottom barrel, through the gear train and up t the engagement. This engagement also needs to push the pendulum ever so slightly to keep the clock running.

Electronics
The LED lighting system consists of the LED light strip from adafruit.com called the Neopixal light strip. This light strip is controlled by a single signal wire which in turn is connected to individual shift registers imbedded in each Neopixal. This level control allows the user to choose any color in the spectrum and display it. A small photo cell may be placed within the circuit to allow the system to switch on and off depending upon the ambient lighting The pendulum sensor is a CNY-70 coupled with an LM-358 Op-Amp. The CNY-70 is an infrared emitter detector and the Op-Amp is set up in a comparator circuit. This allows the Arduino to detect when the infrared beam has been interrupted which in turn calls the interrupt function in the code. The interrupt pin detects a FALLING condition. That is when the signal from the pin goes from high to low the function is called. When the function is called the time is noted and is then subtracted from the time the next call is made. The difference in time is the span of time the pendulum took to make one full period. The period is then converted into beats per minute and sent to the LED 7-segment display. The LED display cannot easily display a floating point decimal. The display can only receive an integer. The following steps convert the floating point decimal into an integer. Say the number is 12.34 the code will then multiply the number by 100 making it an integer that equals 1234. The first matrix command divides by 1000 leaving us with 1.234 however the “mod” function will eliminate the decimal portion of the number and what we are left with is simply 1. The next step will convert the tens spot and is dividing the number by 100 and again using the leaving us with the next digit 2. A line in the code will then turn the decimal place on in the appropriate location and the remaining digits are dealt with in the same manner as the first two.

Team Bio's

 * Matthew kologi
 * I was raised in the small North Idaho town of Wallace. My time spent there was almost exclusively outdoors during all times of the year. I began my interest in engineering when I entered 7th grade and became eligible to begin taking industrial design classes such as AutoCAD and shop. It did not take long for me to realize that I wanted to eventually become a mechanical engineer. In the years following I rebuilt motorcycle engines, lawnmowers, and anything that could be taken apart for the adventure of the thing. I came to the University of Idaho because of the relative closeness to home and the fantastic engineering school that was right in our back door. The university has shaped myself academically, professionally, and personally into who I now am. I became a member of Theta Chi Fraternity and eventually served two terms on the executive committee, one of them being filling the role as president. After graduation I intend to remain at the University of Idaho and continue my education through graduate school and serving as a member of IEW. My area of interest involves mechanical design and optimization of systems from a mechanics of materials point of view.
 * Jacob Sabata
 * I am from Spokane, Washington. I moved there when I was a sophomore in high school.  Before that, I lived over by Portland, Oregon.I want to be a mechanical engineer because I like to solve problems from mathematics and physics, especially statics and dynamics. I was excellent in those fields in high school.  Also, I like to computer-aided drafting, like SolidWorks and Autodesk Inventor.  I figure that being an engineer would be best for me because this field of study comprises all of the elements that I like. After graduating from college, I want to work for a computer-aided drafting company, especially in SolidWorks.  I am pursuing to go into this career because drafting is easy and intriguing for me.  Also, I like to draw and see objects visually.  I prefer not to go into other mechanical engineering career pathways because they are too highly technical for me.
 * Chris Roberson
 * I was born an raised in Long Beach California. I moved to Sandpoint Idaho when I was 14 years old and went to Sandpoint High School. While I was there I discovered that I needed to know how machines and electronics worked on a higher level, so I decided to pursue a career in engineering. From there I wanted to go to a great school that was still close to home, so here I am. Once I graduate I would really like to get in to the aerospace industries, or anything that involves airplanes or objects that fly.My hobbies include: rock climbing, golfing, radio controled toys, and playing games.
 * Erik Illum
 * I grew up in Idaho Falls, Idaho and after graduating from Skyline High School entered into the service of the United States Marine Corps. As a Marine, I served as a combat engineer trained in construction and demolition. Most memorably was the time spent in Kenya clearing ground and building a maternity hospital to establish a clean, safe place for the women to deliver their babies. Following my time in the Marines, I work at the Idaho National Laboratories as a laborer. This led to positions with several companies as an independent contractor in tasks including real time radiography, drum vent operator and flammable gas sampler/analyzer. Surviving layoffs without a specialized degree proved challenging and after several rounds, this pushed me to take steps toward achieving my bachelor’s degree in Mechanical Engineering. After graduating, I hope to pursue a career and possible further education in the fields of robotics and mechatronics. I am especially interested in using these fields for my long-term goal of developing and building self-sustaining aquaponic greenhouses—combining aquaculture, hydroponics, robotics and mechatronics to produce low-cost, natural fish and produce.