For ME 121 (MechE Lab 2) we have a LabVIEW homework due this upcoming Sunday night. The basic idea is that in teams of two we are to create a slot machine that never loses. The player inputs the number of times they want to play along with a few other parameters. Then the player presses a button to spin the machine. The machine produces a set of three random numbers and will continually cycle through them until all three are equal to each other and the player “wins.” Our program has to count the number of times it takes to get three-of-a-kind, while simultaneously flashing lights indicating which numbers match. After it did all that it also had to export the winning number data to a spreadsheet file.
While it seems like a relatively straightforward task, it is actually pretty difficult for myself and the other teams I’ve talked to. It seems like most of us have little experience with LabVIEW, so when it comes to building arrays, reading from/writing to files, etc. most of us are pretty lost since we’ve never done it before using this type of program. My partner and I spent a lot of time on google and help forums trying to figure out how to use certain functions. It’s been frustrating since there isn’t really a TA for the class that holds office hours. We’ve gotten help from Prof. Angstadt several times though and are almost done with the program. The last thing we have to do is figure out how to read the input from a spreadsheet file and also have our slot machine play a sound file when the player “wins.” Now that we are almost finished its pretty satisfying to see it work. In the future I hope we are forced to use LabVIEW more because it seems like a really useful skill to have.
After another week in our manufacturing lab we have made solid progress on our project. In the next few weeks we are responsible for finalizing the tool paths for our molds and machining them. We’re lucky because Prof. Angstadt made template operations for us that we just have to copy/paste and change a few parameters. Creating tool paths is challenging because it takes a fair amount of strategy. You have to take a lot of things into account that you normally don’t think about, like a tool breaking for example. My team sat down together to figure out the best order of operations to machine our molds. Since our car is tiny and has small features like tiny wings and a small cockpit, we wanted our finalized product to have a very smooth outer finish, this requires a lot of operations so we had to do our best to keep machining time down.
We started of with large tools and worked our way down to the small tools, doing cavity mills first. Then we switched back to larger tools and did a similar process for the contour milling operations. From start to finish it’s estimated that both of our mold plates will take ~2 hr. and 15 mins. We were advised to keep our milling operation less than 2 hours, but exceptions are made for cars with more complex geometry which I think our car has. We are graded on how accurately our molds will reproduce our model car so its important that we get our tool paths right. We are very close to having our paths finalized, all we need to do is get approval by Prof. Angstadt and then make a few modifications to the G-code. After that all we have to do is sign up to machine our molds and then make a few cars using the injection molding machine. The race competition is in about a month so we’ve got to get everything ready before then. More updates to come!
I’ve noticed that this year I’ve seen a big rise in the amount of 3D printing I’ve done for my course work. Prior to this year there wasn’t really much to do with it in the intro-level classes I was taking like dynamics, statics, etc. This semester I have two classes in which its very helpful and even necessary. For IPD (Integrated Product Development) we have just started the design phase for our project. With lots of different ideas floating around it’s helpful to have a solid model (pictured above) to hold in your hand when you explain to someone, like a professor, how you think it’ll work. Since we are in charge of designing an actuation mechanism, a solid model is very useful when asking for input from others. In my manufacturing class we’ve also done some 3D printing. Yesterday I posted the picture of our model car that we plan to make via injection molding. Hopefully it turns out just as good as the 3D printed model! Its nice to see how easily 3D printing has been integrated into the coursework and how Lehigh has really embraced the technology. What’s really great though is that printing for coursework is 100% free, so as students we are encouraged to really experiment and prototype which is a lot of fun.
Yesterday during our normal lab time, my team and I finally got a chance to meet with our middle school students that we’ve been working for the past several weeks. Unfortunately only one of them could attend but we still had a nice time together. Our student brought with her the 3D printed model that she printed at the middle school and it turned out even better than we expected! Initially we were afraid that the wings would be too thin or that the spacing of the bases wasn’t the best, but after holding it in hand we feel much better and aren’t worried about that now. We asked her if there was anything she would like changed and we were lucky that she said she was fine with the way it was. Although she did want us to change the colors around in the solid model, she wasn’t a fan of the bright green and pink.
While the middle school students we here at Lehigh they did a small tour of the workshop and saw how to operate the water jet used to cut plate and sheet materials. When the students were in the lab with us we showed them the general process on how to make parts using 3D CAD software. We were given a sample piece to make with them, a team nameplate and display stand (seen below). We will 3D print this display stand which will be part of the race day competition later this semester. We came up with the team name Stratosphere, we thought it sounded cool and related to our design well.
Yesterday we made further progress with our mold design. We finalized our pin locations and pin lengths. We also adjusted our runner and gate sizes. All that’s left now is to get our mold design approved by Prof. Angstadt. He’ll inspect our whole design and check for any errors we could have made. There is only one aspect of our mold that concerns me. On the movable mold plate, the top half of our plane is sitting on an extrusion instead of sitting in a cavity. I’m afraid that when the mold plates separate the top half of the plate will want to stay stuck in the stationary half of the mold. This would be a big problem since the stationary part doesn’t have ejector pins. We left some of the pin lengths short so that the cavities fill with plastic and will hopefully keep the plane attached to the correct mold but we’ll have to see if Prof. Angstadt thinks that’s a viable solution. We are going to try and get our mold approved before the end of the week. More updates to come.
While ME 242 is titled Engineering Vibrations and Systems, we’re just now starting a section on electromechanical systems. Electromechanical systems are so important because they are just about everywhere you look. Prof. Chew always loves to reference cars and the automobile industry during his lectures. He worked for General Motors for many years before he began his teaching career. Prof. Chew says that in cars nowadays there are very few purely mechanical systems, since most have been coupled with an electrical system. This marriage between disciplines is reflected in some of the material we’ve been going over recently. This class really brings together ideas and theories from past mechanical engineering classes, electrical engineering classes, and even some past physics classes as well. In fact, this class has incorporated more of my prior course work than any other class I’ve taken. The class is difficult too, because it requires a deep understanding of all this prior theory, some of which may be quite dusty in the back of one’s mind. We have a bi-weekly exam coming up this Friday that I’ll be studying for all week. Wish me luck!
This week more progress was made in creating our model cars for the middle school students from Broughal. This week we were tasked with creating our molds. While this sounds like a relatively simple task, its actually quite complex. After adding our car parts to the mold assembly we had to make some decisions that could have a big influence on how the car will come out in the future.
First, we had to decide where exactly in the mold to place our car parts. This is important not only because we obviously need all of the parts to fit but because it requires us to choose which ejector pins will physically be used to eject our car from the mold. Its recommended that at least three pins are used to remove a part, however based on the somewhat strange shape of our plane/car we ended up having five or six pins to remove the big body pieces. After choosing part locations we had to then remove and add material in the shape of our parts on the mold. This was done using cavity and extrusion tools in SolidWorks. After that we had to design the runner system as seen above. These designs are likely to change in the future. We’ll import our part files into Moldflow and run some simulations to optimize the runner system. This will change our runner diameter and change the gate size as well.
Now that our molds are finished we’ll start the tool paths in NX. Then we’ll have to submit everything and hopefully get approved to continue. After that there won’t be much more to do other than to start physically making things. Next week we’re going to meet with the middle school students and talk about the design, show them step-by-step the process we take when we make things. I’m looking forward to meeting our young design partners and I’m excited to show them how we work. More updates to come!
After months and months of applying, waiting, interviewing, and waiting some more I have finally accepted an offer to intern at NASA’s Ames Research Center in Mountain View, CA. I’ll be working as a member of the Aeromechanics Team focusing on rotorcraft research. I’m ecstatic about the opportunity and I can’t wait to begin to 10-week internship in June. I’ve never been west of Pittsburgh so this will be a great travel experience for me. What’s surprising about this opportunity is that it was one of the most popular internships and received just under 700 applications! I was one of the lucky ones and received an offer over spring break. In total there’s expected to be around 50 or 60 interns at ARC this summer. I’m lucky to have Prof. Terry Hart as my academic adviser. As a NASA astronaut himself, a letter of recommendation from him really helped my application. Its times like this that make me very glad I chose to come to Lehigh.
However, lets take a step back though and look at the whole internship application process. It started early on last semester at the Fall Career Fair. I began by distributing my resume and getting contact information at various companies. After that I applied to some positions listed on the LUCIE website (career services). I applied to GE, Lockheed Martin, Volvo, Voith Hydro, DuPont, W.L. Gore and others. While waiting to see if I had any interviews from those, I researched companies and applied to their own postings online on the company websites. I applied to positions at Lutron, Boeing, Lockheed Martin (again), Orbital Science, Northrop Grumman, NASA, and others as well. In total I applied to somewhere in the range of +/- 60 positions with varying roles in mechanical engineering.
I really only heard back from seven or eight companies, some of which just informing me that I was not chosen for the position. I had been selected for five interviews: Lutron, Voith Hydro, DuPont, W.L. Gore, and NASA. Some interviews were over the phone and others were in person on campus. I personally think that my interview skills are much better in person so my phone interviews weren’t the greatest but I didn’t think they were bad in any way. Some of my interviews I thought went really well, I thought I had nailed them. Unfortunately for me that must not have been the case, I was rejected from just about everything. This is what makes this whole process somewhat funny. One would think that I’d have the smallest chance of getting a job with NASA due to the level of competition but it was the opposite. After weeks and weeks of waiting and being denied from job after job I was beginning to get discouraged. I thought about trying to find a research position here at Lehigh for the summer instead. Then, over spring break I got my offer from NASA. I technically got two offers (out of the 15 positions I applied to), and chose the position at ARC.
But the scary thing is that now that this process is over another one fills its place…..job hunting for after graduation. Oh boy…..I hope that goes a little more smoothly.