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About Me


Matt Rockar


Computer Science

Contact Me

Email: [email protected]



Week Thirteen

I wish the course discussed modeling objects more. It is great to now be able to print objects, assemble a printer, and diagnose and troubleshoot problems with the printing process and the printers themselves, but I would have liked to learn a little about how to make my own models to print. From dealing with the printers, I’ve learned what the limitations there are on designs and what file type I need to get my model into, but I don’t have much of an idea of how to model an object. One or two days spent using Blender or Google SketchUp to create an object that demonstrates the basic techniques you would use to model objects would have been interesting and very beneficial. Something like designing one of the y-axis brackets or another small, simple piece would have been nice and would have allowed students to try redesigning pieces that they thought could be better.

Week Twelve

I would push for focusing on the filament recycler. The dual extruder is a great idea and it would allow us to print support material in PVA that could be easily removed with water. This would allow us to print objects that we normally couldn’t print due to the restrictions of the RepRap’s capabilities. The reason I would choose the filament recycler is that we could then buy PLA pellets and extrude our own filament as well as recycling our many failed prints The difference in price between PLA filament and PLA pellets is ridiculous. The savings from making our own filament would allow us to use funds for other projects. The dual extruder and filament recycler both advance the RepRap project by expanding the capabilities of the printers and lowering the cost of materials respectively.

Week Eleven

After working with the OHM RepRap design for a while, there are a few parts that I would redesign. First would be the z-axis couplings. They are very difficult to attach to the motor drive shaft and the threaded rod. They also require some material on the motor drive shaft to properly grip them. Second would be the x-z assembly for lifting the x-axis assembly. We had difficulty with our nut traps not holding the nuts at the proper angle, which caused so much friction on our threaded rods that they would stop spinning. The nut traps are a nightmare to assemble and screw the bolts into. Third would be the x-axis motor mount and end bracket. The prints are so big that we had a lot of difficulty printing them without major warping. Even the pieces that we eventually used on our machine have an (acceptable) amount of warping. To improve the z-axis couplings, I would redesign them so that they can be attached to the motor drive shafts and threaded rods before the motors are mounted in the z motor mounts. This would make attaching them much easier. I’m not sure how to improve the x-z assembly or the x-axis motor mount and end bracket. The only thing I can think of to try to prevent warping in the motor mount and end bracket would be to print them with a raft (which was recently added into Slic3r). I’ve seen a few videos of professional printers (MakerBot Replicator2 and another industrial one I couldn’t identify) print large pieces with a raft and the results had minimal warping.

Week Ten

Seven people wrote about my blog, so I’m guessing that counts as highly rated. I have a few bits of advice for emulating my blog style. First, I would recommend making a rough outline for your blog response. This will help you keep on track and not wander off-topic. Second, be concise in your writing. Try to get your meaning across with as few words as possible. Throwing in words to spice up your writing is nice, but too much and you risk your reader becoming bored. Third, have someone else read your post or come back after an hour or so and read what you wrote. This will allow you to see your writing from the perspective of your reader. Often, if I try to edit what I just wrote, I’ll read it as what I wanted to write and miss errors or clunky phrases. I would organize my responses in the same fashion for maximum XP for the rest of the course. The only thing I would do differently is to try to do a little more editing.

Week Nine

Laser-scanning models offer a higher resolution than a photo-based method. The laser-scan method utilizes a laser to find the points in space of the object’s perimeter. This requires hardware to project the laser onto the object and a receiver to capture the reflected light. The cost of this hardware is much more than the cost of a quality camera. The software interprets the time between projection and reception as the depth of that point in 3D space. The object is rotated slowly to build a cloud of points that can be connected together as a 3D object. The photo based method uses a series of pictures from different angles to accomplish something similar. Instead of a series of points, the photos are analyzed to find reference points. The reference points are found in the other images and further points are recognized. The difference in the angle of the camera is used to figure out the location in 3D space of the reference points. From this, the 3D object is built. The actual positions are not found, like in the laser scan, but extrapolated from the series of photos. The photo method has several drawbacks. The first is that the resolution is lower. The second is that it is more difficult to extrapolate the 3D object from the photos, which may result in errors in the resulting 3D object. The third is that it takes more work (many photos need to be taken manually). I was able to find one open source photo based software, insight3d.

Week Eight

Blog 6

Bill Fabrizi - post

I find this post to be insightful because Bill discusses how 3D printing is making its way into several industries and that the President of the United States acknowledged how important this technology was to American manufacturing. He also makes some very good points about the differences between university classes using commercial printers and classes like ours that use open source printers.

Carina - post

Carina does a good job of explaining why 3D printing is so important and how it being mentioned in the State of the Union address show it has a promising future. She also gives very good insight into how 3D printers would benefit students in mechanical engineering, but also how the cost of the systems and additional time needed to get to know how to use the equipment would be potential flaws. She has some good thoughts on the differences between UVA’s 3D printing program and our own and she is hopeful that our printers (with enough tuning) could potentially print as well as their commercial systems.

Mark Keller - post

In Mark’s post, he does a great job of explaining the importance of the State of the Union address. He talks about how Obama wants 3D printing to bring manufacturing back to America and how it could greatly benefit the education system by bringing this new technology into almost all classrooms. He also does a great job in discussing UVA’s 3D printing program and is able to give his own insight into how it may help dynamics students understand the complicated problems much better than a picture in a book could. He doesn’t forget to mention the downsides of using the printers, which mainly are the time it would take to train to use them and the possible time it would take to maintain and fix them.

Blog 4

Bill Fabrizi - post

I found this post to be very thoughtful and interesting. Bill makes a good point when he discusses the astounding cost of what a professionally done prosthetic may cost and how the prosthetic would be grown out of, resulting in massive amounts of medical bills over the years. He discusses the benefits of being able to rapidly prototype many different versions of the hand and how the hand can be quickly changed and adapted as the boy grows.

Carina - post

I liked this post a lot because it had a nice table comparing the differences between the open source replacement hand and the closed source model. She listed many differences others had talked about, but she added the limitations in movement of the printed hand, which I do not think I have seen anyone else discuss.

Mark Keller - post

Mark’s post is very good. He has a detailed analysis of the differences between the open source replacement hand and a comparable closed source version. He mentions how the closed source version is computer controlled, which allows it to do many things that the open source version can’t such as changing grip strength and the ability to pick up small objects. He also mentions that even though the open source prosthetic is unable to do many of the things the computer controlled version can, it is much cheaper and easier to repair which makes it perfect for those who cannot afford such an expensive and complicated medical device.

If I were to award XP for the blogs, I think Mark Keller would get the XP for both of them. Not only are his blogs good looking (pictures, nice formatting, etc.), but he goes very in-depth in both of them and makes many good points. His structure and writing style are nice and enjoyable to read.

Week Seven

Part A

The 3Doodler is an interesting concept. It allows people to create 3D objects using a relatively inexpensive device. I don’t see it as anything more than a fun toy though. It would be fun to mess around with for an hour or two, but I don’t think it would be useful for the majority of things a 3D printer would be used for. The Formlabs FORM1 printer is amazing. It is a wonderful piece of hardware for only $2,300, where comparable printers sell for more than $10,000. The print quality is extremely good and the ability to generate supports that easily break off is great. The only drawbacks I can find are that the printing process it uses generates a lot more waste (since the resin bath can only be used for one model) and is much more expensive. Other than that, I think it is a great achievement in making 3D printing more affordable. 3D Systems is suing Formlabs because they may be infringing on a patent on how the printer operates. I think the 3Doodler is making headlines lately because it is an inexpensive way to (kind of) try 3D printing.

Part B

I think that Kickstarter represents the future of crowd-sourced fundraising. I’ve followed it for awhile now and I’m glad it is doing so well. Initially, there was a lot of skepticism about it since people could raise money and potentially never use it in the matter they said they would.

Part C

The drawbacks of Kickstarter are that after raising all of the money, you have to pay taxes on whatever you received, you have to spend the time producing and shipping out all of your rewards, and you have to sink in quite a bit of time to get the word out about your project. There is also the drawback of Kickstarter becoming more about marketing your project rather than raising money for your project. Kickstarter is like a store where you can chip in to buy a product that doesn’t exist yet. The differences between Kickstarter and a store are that the thing you buy may not have even been made yet and you may not even get the item you’re helping to fund, but some other kind of reward. There are a few alternatives to Kickstarter, which can be found here.

Week Six

Part A

The article is essentially talking about how 3D printers are the future and more focus needs to be put on them. It talks about how 3D printers are affecting many different industries and how they are revitalizing the manufacturing industry in the United States. It also discusses how the printers are useful in education as a way of connecting conceptual ideas to real world objects. Finally, it talks about how more focus needs to be on 3D printing since the technology is beginning to advance so rapidly. The key points that I took from the article are that 3D printing is going to affect many different industries, it is very useful in engineering education, and that the technology is evolving very quickly.

Part B

This year’s State of the Union address was mentioned because Obama talked about 3D printing in it. This is very important because it highlights how new this technology is and how much potential it has to revolutionize so many things. It’s still in its infancy, but 3D printing’s applications are growing and the costs are falling. Right now 3D printers could be compared to computers in the 70’s and 80’s. They aren’t perfect, but people are still improving them and discovering new uses for them.

Part C

Using 3D printers in education is a good idea to me. It will get kids excited about STEM and hopefully inspire them to learn more. As for the undergraduate engineers, I feel that using 3D printers to create 3D objects of the parts they are studying would be greatly beneficial. I can understand how difficult it would be to mentally visualize some complicated mechanical system and I think that being able to print the system and examine it close up would help one get used to dealing with systems like that. The main flaws I can think of are the relative danger of younger people trying to use the machines. The cost of using a 3D printer might be a hindrance, but I’m sure the prices of the materials will fall in the near future. Other than that, I think it is a great idea.

Part D

The printers used at the University of Virginia are “nicer” than our printers, but I’m pretty sure they cost at least an order of magnitude more than our printers. Their printing material is also probably more expensive. Their printers are most likely nicer and print more accurately. If we tried to mimic their program, I think it would be just as effective if not more so. With the right care and calibration, I think our printers would be able to function almost as good as theirs. The benefit of our printers is that more could be easily made from one printer. The other benefit is that students would get more hands on engineering experience troubleshooting and repairing the RepRaps. Instead of a giant box that spits out perfect models, you get an example of a real-world machine that breaks down and has issues. Fixing the printers, designing improvements, and being able to see how they function would greatly benefit any future-engineer.

Week Five

Part A

Settlers of Catan Border

I do not think this is copyrightable, but it may be patentable. There aren’t any creative or artistic elements to it that make it a work of art. It does have the utilitarian purpose of holding the Settlers of Catan board together.

8D Cubic Lattice

This is not copyrightable or patentable. It has not utilitarian purpose and it is in about the same boat as the Penrose triangle. It is a sculpture, but it isn’t original. It is a design for a mathematical structure that has been around for a long time in theory.

Rocky Rocket

This is not patentable because it has no utilitarian purpose. It may be able to be copyrighted because it is a creative sculpture, although I feel like someone else may already have a copyright on a 50’s-looking rocketship already.


This isn’t patentable because it has no utilitarian purpose. It may be copyrightable because it is a creative creation. I think the bigger issue with this is that it may be infringing on the Battleship trademark held by Hasbro.

Temporary Tooth Implant

This isn’t copyrightable because teeth aren’t an original creation, but it may be patentable. It serves the utilitarian purpose of providing a cheap tooth implant for dental patients.

Part B

The Caddyrack would be copyrighted since it contains the Cadillac logo. Mumble the Abominable Snow Monster would be copyrighted since it was created for a movie. Same thing goes for this Minion from the movie Despicable Me. This Camaro Nervoso would probably be protected under copyright for the design of the body of the car. This Stormtrooper valve cap would also be copyrighted.

Part C

I would be interested in the licensing of non-copyrightable files because attaching something like a Creative Commons license to your work would be a way of showing the community that you are OK with your design being shared and modified. While it may serve no actual purpose, you are giving the OK for people to do what they want without fear of getting a take-down notice or a call from some lawyers. It is also useful to help protect your design from future laws restricting it. It’s a way of preventing future legal-stupidity from quashing the life of your design.

Week Four

I was extremely happy to see that such a project existed and even happier to see that 3D printing was able to help the project evolve even faster. How they were able to each have a printer and collaboratively design and improve the hand from across the world is amazing and really highlights the benefits of the technology. It also allows for the prosthetic to be made more cheaply and the components to be easily modified to work for other individuals.

This technology compared to a closed-source version is more clunky and needs improvement. The benefit of open-source is that anyone can help out and add their own improvements to the design. While closed-source may have access to more engineers, better equipment, and possibly a higher quality design, this all comes at the cost of the end product being much more expensive than the open-source production. Open-source would allow this technology to reach those that truly need it and at a fraction of the cost. Hopefully, over time, the design will reach a point where it will rival closed-source versions.

The open source project from the article is located here. We would be able to participate by improving the design. We could work on improving the strength of the components and maybe even turn the design into a parametric one so that anyone with this condition would be able to print a prosthetic that would fit perfectly to them. A parametric design would also allow children like Liam to print out a new hand whenever they outgrew their old one.

Week Three

Civil Engineering

The printed building idea seems like a great use of the technology. Buildings could be constructed with almost no human interaction much faster and more efficiently than before. Homes and businesses could easily be custom designed for different aesthetics and purposes without much trouble. The cost of building would be greatly reduced and allow for cheap, yet high quality, buildings to be easily built. This could provide cheap housing for the millions without it. If the technology is adopted, I’m sure it would be revolutionary.


Printing organic tissue and possibly organs would be amazing. Instead of waiting for a transplant, a new organ could be created using a person’s own cells, which would reduce the chances that it would be rejected. Aside from that, 3D printed tissues and organs could be used for medicine development, which would reduce the cost greatly and allow for more human-specific testing to be easily done. Lab animals everywhere will be so happy.

Food Science

3D printing would be a great tool for food science if it becomes more affordable. Being able to print a steak with the perfect marbling would be something I hope to see in my lifetime. It would also improve the efficiency of producing meat. Instead of big barns full of cows, processing plants, and butchers, a machine provided with a biomaterial could print different cuts of meat or even types of meat for you. The whole process would be much greener and possibly allow more people access to a bigger and better variety of food products.


I’m not a fashion expert, but I can appreciate the creative applications of 3D printing in the fashion world. It would allow for more creative and interesting design to be created. Since it’s a completely different method of producing an object, it allows for things that were not possible before to be created.

I found a few examples of 3D printing affecting other areas of human endeavor. One is the Urbee, a hybrid car whose frame was 3D printed. 3D printing also allows for customizable prosthetics like the leg we saw and even a printed jaw replacement.

Week Two

I do recognize the features we use on every computer today. The mouse and cursor were impressive for the first one seen in public. I imagined the first one to be much clunkier. It also seemed like instead of keyboard shortcuts for copying, pasting, etc. Douglas Engelbart was using a second keypad that had buttons for each function. How the data was structured was interesting too. The idea of a file being made up of statements and statements being made up of words seems like an intuitive way to store information. I think it’s nice for human-readable files, but not great for storing all forms of data. I am impressed, but I think it’s because I can understand how much work went into making this demonstration. If I didn’t know as much about computers as I do, I feel like I would be unmoved. People take for granted the research and work that went into creating the modern computer. I think I would have even recognized the importance of this at the time because it is revolutionary. This is a time when personal computers weren’t an everyday thing. Data was written down and manually processed. To perform the simple edits that Douglas did, you would have to get a new sheet of paper and retype your document with the edits. The ability to delete words, edit words, copy and paste, and even preview statements would speed up anyone’s workflow. I would say that I had a similar experience going from an old cell phone to a smartphone. Little things became easier for me and I was able to work faster and more efficiently. The things that Douglas demonstrated seem trivial to us today, but we just don’t realize how much they have helped us.

Professor Richard Doyle says that the initial perception of the mother of all demos was a hoax. People couldn’t believe that a computer could be doing what they were seeing. They thought that it was people moving boxes. We should and do share our information because it allows for more input and faster innovation. It allows for individuals to use our knowledge to create what we have created and even improve upon it using individual creativity. We share in order to speed up advancement in the technology. We could better share our knowledge by creating and expanding documentation on the wiki for the OpenHybridMendel. We could also create videos for YouTube on both the construction and operation of an OpenHybridMendel. A visual aspect may help people better understand and it being freely available online would mean that anyone could learn about the project.

Week One

Part A


Settlers of Catan Border I play Settlers of Catan every so often and my border pieces are starting to not hold the board together well during a game. This seems like a great replacement for the cardboard border.


8D Cubic Lattice The math sculptures on Thingiverse are all amazing. It was hard to choose, but this one looked interesting to me. I think being able to print such complicated structures that would be difficult, if not impossible, to create using other methods is awesome.


Rocky Rocket It kinda looks like an old school sci fi rocket, but not really.


Battleshots The idea that someone turned the board game into a printable drinking game is hilarious. I don’t think I would ever be able to finish a game though.


Temporary Tooth Implant This is a temporary tooth implant as the title suggests. I find it strange because I don’t think I would want to stick something I printed into my jaw.

Part B

I feel that I am a tinkerer. When I was younger, I would take things apart and try to put them back together. Around thirteen or so, I became interested in computers and robotics. That was when I started building robots from kits and eventually put together my own computer. I really enjoy figuring out how things work and making them better or repairing them if they break down. I think my dad is also a tinkerer. He always has a project going on and loves finding new things to try to create.

The argument about the influence of corporate culture on tinkering is pretty spot on. Corporations don’t want people poking around in their proprietary designs or figuring out cheap ways to keep gadgets running instead of buying the latest, more expensive one when your old gadget breaks. I feel that tinkerers are necessary and the article is right about preserving their habitat being essential to getting the nation back on track. Tinkering is essential to innovation and since manufacturing has been moved out of the country, we need to focus on creating new products and improving the design.

The primary design principles that I took away from the interview are to use an iterative process, watch how users use your product, and keep it simple. I thought it was great to see that he and his daughter were building a 3D printer. I think he will be able to really utilize the rapid prototyping process very well. I think his principles would apply to our work and are mostly already in place. The RepRap project is an iterative design process and the users are directly involved in improving the design and fixing issues that they find.