3D printed parts are spectacular for quick prototypes that don’t experience large amounts of stress, but they eventually fail at higher loads. Curious about casting my own metal parts, I was inspired to build a small aluminum forge after seeing a few tutorials online.
An old propane tank served beautifully as the body of the forge after the top was removed with an angle grinder. I cut a small hole in the side of the tank near the bottom, and welded a few feet of one inch diameter steel tubing over the hole. This is for airflow, making the charcoal much hotter than it would be under normal conditions.
I attached a thrift store hairdryer to the other end with some trusty duct tape. This will blow air through the tubing to increase the forge’s temperature. The next step is to fill the forge with charcoal and a thick steel soup can for a crucible, light the charcoal, and turn on the hairdryer!
Once the hairdryer had been running for a few minutes, I checked the charcoal. Although the charcoal was red hot, the can wasn’t glowing yet. I gave it a few more minutes until most of the bottom of the can was at least a little orange. Then, i started putting aluminum cans into the crucible, and pushing them down as they melted.
One by one, the cans got swallowed up by the molten pool of metal, resulting in a half-full soup can! Using a bit of Sugru, I made a makeshift mold of the greek symbol Pi. After clearing the impurities off the surface of the molten aluminum, I poured some into my mold. Aluminum Pi!
Last fall, I applied for a grant called the UConn IDEA Grant through my university to build a 3D printed prosthetic hand controlled with an EMG sensor. EMG stands for electromyography, which looks for the voltage in a muscle using a small adhesive pad. I started off by designing a hand in Inventor that doesn’t utilize the EMG sensor and just articulates like a normal hand.
Needless to say, my first versions were less than pretty.
Never mind pretty, most weren’t even functional. But going through the process of creating a hand from scratch and making quite a few models that don’t do what they should taught me a lot about how to make them work. Finally, I had created something that worked.
The two main things I learned from this version were that the fingers did not work well being made out of rigid material, and that my thumb design was quite useless. A real thumb moves using many compound angles, where mine moves in just one, and not a very useful one at that. I knew at this point a serious overhaul in the design was necessary.
The next step, however, was building the circuit that would run the hand. I ordered all the electronics, and prototyped them on a breadboard to make sure everything worked as expected.
After the electronics were all figured out, I had to find a way to contain and arrange them. Thus began my numerous attempts to create the “forearm” of the hand that would house all the electrical components.
Next, I began designing a hand that could be printed in all one piece. But in order to make this happen, I would have to print in NinjaFlex, a flexible 3D printer filament from Fenner Drives. Ninjaflex is incredibly hard to print due to its flexibility. Two things can help printing with NinjaFlex to keep it from messing up; the filament should be tightly constrained from the extruder stepper all the way down to the nozzle, and the print speed must be decreased significantly.
The stock extruder for a Lulzbot Taz 5 doesn’t support flexible material, but Lulzbot is an Open Source company, releasing all their files and build notes online. I went hunting through their forum for a thread that might contain some development notes about when Lulzbot was developing their flexible material extruder, and lo, I found a wealth of information. After printing out one of the prototypes posted in the thread, I replaced the one that came in my extruder, and I was printing NinjaFlex!
When I had designed the hand, I imported it into Cura for slicing.
This picture illustrates the channels cut throughout the hand to allow for cabling to move.
46 hours and 22 minutes later, my NinjaFlex hand was completed.
This print required quite a few hours of cleanup to get into a workable state, but eventually it was moving in the way it was designed.
Finally, all that was left to do was install the electronics in the slightly redesigned forearm piece, wire up the fingers, and finishing touches!
I took the hand to the 2015 World Maker Faire at the New York Hall of Science, and exhibited for the weekend! I met a tremendous number of cool and interested people, and made some fantastic connections for the future of this project.
All development files including STLs and Arduino code can be downloaded here.
In my Intro to Engineering class during my first semester at UCONN, I was assigned a group project of creating a catapult using limited resources. We were given a budget of imaginary currency, and a catalog from which we could “purchase” materials that we could build our catapult with. The catapult had to shoot a ping pong ball to hit two targets at set distances away. A combination of least amount of currency used, and high degree of accuracy with your catapult shot would win you the most points.
I decided right off the bat that I wanted to take complete creative control over this project. I typically enjoy working as a team, but for this project I wanted to really test myself and see what I could do. I picked teammates that agreed to allow me to do all the work for the project. As soon as we were signed up, I drew up a materials list, spending the smallest amount on materials that I could manage while still purchasing what I needed.
I immediately got to work after purchasing my materials from the engineering department’s office. After driving home to pick up some tools, I began hacking my plywood into pieces dictated by the template I drew up beforehand. In a few hours, I had the frame assembled, and the next day I had calibrated the tension in the rubber bands so that the catapult would fire consistently to where the targets would be.
As an extra credit component of the project, we could automate the firing process using an Arduino microcontroller and a small stepper motor. After writing a quick bit of code, and attaching the motor and Arduino, the catapult was finished.
After the competition, my catapult came in first in regards to accuracy of shots, the first target being hit exactly in the center, and the second shot landing about a foot away from its target. With the cost of materials taken into account, my catapult came in third, still winning me and my team some prizes from the engineering department.
During my freshman year of college, my friend Nick expressed an interest in being Wolverine for Halloween. His thick wiry hair and ability to grow impressive sideburns made Wolverine an ideal choice for a costume. I decided I would help him out and build him a pair of custom Wolverine claws!
First off, I went out to my local hardware store and bought a ton of cheap welding steel. I brought a template I cut out of card stock that fit my design, and made sure the profile fit easily on the stock I purchased.
I ended up purchasing a ~2.5 inch wide, 1/8 inch thick flat plate of steel for the blades, and a few feet of square steel tubing for the grip, and to connect the blades together.
When I got the steel home, the first step was tracing out my template six times on the flat plate. Unfortunately, at the time I didn’t own a band saw, or any other tool that would make cutting these templates out easy. I was forced to use my angle grinder to cut them out, which took an incredibly long time, and was finicky to accomplish.
Before long, I had six “blade” cutouts. These burr-covered wrecks still needed a fair amount of work before they were ready to be welded together. Thus began the tedious process of grinding down every blade, sharpening each edge, and making them all as uniform as possible.
Finally, six beautifully sharpened, polished adamantium blades. From here, all that was left to do was cut two pieces of the square tubing approximately the width of my palm, and welding the blades to them. After a final polish and application of lacquer to prevent rusting, they were ready to go!
This object is an adapter for my grandfather’s vacuum cleaner so that it can suck the air out of Space Bags. Previously, he was using a toilet paper tube which leaked a tremendous amount and prevented him from being able to remove a significant amount of air from the bag.
Above is the sketch my grandfather sent me that I based the model off of.
This is the designed object placed and sliced in my printer software, ready to print.
Finished product. Printed at 100 micron layer height using white ABS. The part is airtight, allowing it to work properly.
Stakket is a RSS Feed Aggregator. It takes up to twelve RSS feeds and combines all of their posts chronologically. You can organize your feeds into three “Stakks” of four feeds each, and view them separately, or all together. I learned php and SQL while producing this site. I had the main functionality of the site functional in 40 days.