The Corner Case

What better way is there to spend multiple consecutive weekends than sitting at your computer, redesigning a mechanism that has existed for decades, all to be able to 3D print something that can be bought at the store for less than $1? ... That's right, anything. However, when your co-worker throws down the gauntlet there is only one thing to do. Take it up.

Going off the success of my 3D printed dial calipers, I decided to try to print something even more elaborate. But what to print? I contemplated several options but ultimately decided to print a tape measure. Originally I didn't think a tape measure would be that interesting... I mean, it doesn't even have gears. Once I started piecing it together in my mind and determining the acceptable "cool factor", I realized that the parts count alone was skyrocketing. My calipers had 9 pieces, this tape measure would have well over 100... Now things were getting interesting. I decided to attempt this based on the parts count and the fact that, if successful, I would be able pull out over 4ft of tape from something about 3" sq. Also, I had no better ideas at the time. I designed the tricky parts first, then I printed little test pieces here and there to validate the design before integrating them together. Right around the time I starting adding all the cutouts ...

3D printing initially interested me because of its ability to create physical parts very quickly with nearly any geometry. By the time I had access to a 3D printer the ability to print virtually any shape had already been well proven and had even become commonplace. I was then introduced to the idea that multiple parts could be printed together, assembled, and captured. This may seem like a new concept but it is merely a new way of looking at 3D printing. The printer doesn't care how many pieces its printing, or even if they are connected. I had seen adjustable wrenches printed already assembled. In the same fashion, I designed a c-clamp to try my hand at this concept. The camp worked perfectly. So then the question became "What's next?" Dial Calipers. Yes. That sounded more than complicated enough with its gears, dials, and half dozen moving parts. I guess the irony of 3D printing a precision measurement tool with, what is normally considered, an imprecise man...

One night I was watching an episode of The Big Bang Theory where Sheldon made a telepresence robot to avoid physical interaction with people. As I watched that scene I thought to myself "I could do that." So I did. My main motivation in building this was to use it to telepresence with my family back in the north east. I figured this would be a lot more fun and interesting than just the usual Skype session.  The design is pretty simple: a motorized base with a laptop up top and a webcam. The base has two geared brushed motors which are controlled by the laptop via USB. I used a Maestro from https://www.pololu.com/ which lets you control standard r/c equipment from a PC. I then wrote a little C# windows app which connects to the Maestro and then could control the motors. This app also could connect to another instance of itself over the internet in either a master or slave mode which would allow external control. The webcam was mounted on a simple gimbal which allow...

This is the most mechanically complicated plane I've ever built. It has a wing span of 9.5", weighs 4.25g, has full flying rudder and elevator, and retractable landing gear. Flight times on this airplane are in the 7-10 minute range with a 30mAh single cell lithium polymer battery. The frame is all made from carbon fiber rod or tube in the 0.5mm - 1.5mm range. The covering is OS film and is 0.5-1 micron thick. The propulsion system uses a 4mm 10ohm motor, geared down 6:1, driving a 3.25" carbon fiber propeller. The servos that drive the rudder and elevator are each 400mg and are my own custom design. Oh, and the tail wheel is steerable. Ground handling on this plane is amazing and arguably the most fly part of not-flying it. Landing gear is very very uncommon on micro planes. So, being able to do things like take offs, landings, and touch & goes just makes this plane very cool. When it does get in the air it flies very slow. Although, it has enough thrust to g...

When I started to take a break from microscopic flying vehicles in 2010 and migrate towards some larger, easier to work with, models (5-20g) I realized that magnetic actuators just weren't going to cut it for control (rudder, elevator, ailerons). Magnetic actuators are heavy and draw power continuously when deflected away from neutral. I needed servos. Servos would provide lots of pulling force for their weight but at the cost of mechanical complexity. Since servos at the weight I needed didn't exist or were out of my price range I decided to further over complicate the situation and build my own. I started by designing a simple linear servo (lead screw design). The picture above is of my 400mg variant which has a throw of about 0.2", resolution of 0.0015", and can pull about a 25g load. The motor is a brushed 3.2mm diameter coreless design by Shicoh. The gears used are module 0.15 and can be gotten from http://www.kkpmo.com/ . The threaded rod is 0000-160, which...

I can't help myself. Every time I build something I invariably think of ways I can build it smaller. I built a large ornithopter, now I have to build a small one. This ornithopter comes in at 920mg, just under 1g, and has a 2.5" wing span. It has 4 flapping wings. The two wings on each side flap towards each other and then away from each other. This produces both thrust and lift.  It is powered by a 8.5mAh single cell lithium polymer battery. Flight times are around 3 minutes per charge. Controls are done through an infrared receiver system which can command the throttle and rudder. The rudder is actuated with a small magnetic actuator. The motor is a single phase brushless design that is geared 10:1 to flap the wings. The frame is all carbon fiber rod between 0.01" (0.25mm) to 0.02" (0.5mm) in diameter. The covering on the tail is OS Film while the cover on the wings is some thin grocery bag plastic film. This is very weird to watch fly. The wings a...

Now this is a bit of a terminology cluster... VTOL stands for Vertical Take Off and Landing; and an Ornithopter is any flapping winged thing that flies (aka, birds & insects). This hot number was pieced together from an Air Hogs Avenger back in October of '08. The Air Hogs Avenger was a nice little 4-winged ornithopter with a little too much thrust-to-weight to remain unmodified. I gutted the system and used the wings, gearbox, and motor to make my own, cooler, ornithopter. I made the airframe out of carbon rod and added elevator control. I also had to replace the radio system to support throttle/rudder/elevator control. Total weight, with battery, is 10.5g and the flight times are over 10 minutes. This vehicle has the ability to take off and land on its tail, almost hover in place, cruise in level flight, and do loops. It is very responsive and aerodynamically quirky (not in a bad way). Flight stability is great, it can be flown with only rudder control by a novice or f...

To date, this is the lightest plane I've ever built. It held the unofficial record of the world's lightest plane for about 4 months back in July of '08 until it was bested by one weighing 225mg. To date, I don't believe any lighter ones have been made. This plane is my crown jewel of micro plane accomplishments... Despite the mountain of headaches it took to build. It has a 3.1" wing span, a 1" chord, and is 3.5" long. Flight times were surprisingly high, around 4-5 minutes, considering the size of the motor. An infrared transmitter/receiver system was used to control the throttle and rudder. The rudder control is done though an electromagnetic actuator. The frame is made of carbon fiber rods ranging in size from 0.01" (0.25mm) to 0.005" in diameter. All the rods less than 0.01" diameter were hand sanded down to size. The covering on all the surfaces is OS film (DuPont). All the electronics in the IR receiver - microprocessor, FET,...

During the time when I was really into building these small planes ('06 - '10) there was a little unofficial competition of sorts going on between the 5 or so people in the world that were building planes this light. Contrary to what one might think, building a small plane isn't as hard as building a light plane. So, there was always a little friendly competition to see who could build a lighter plane. This plane, for about 3 months back in November of '07, had that record. The wing span on this plane was 2.75", the chord 7/8", and the length was about 3.25". The air frame is all balsa with OS film covering. Flight times were about 4 minutes per charge. The controls were done through an infrared receiver which controlled the throttle and rudder. Planes this light become a lesson in frustration. For example, all the "large" components of the receiver (microprocessor, IR detector) were sanded down to the copper die to reduce weight....

I built this back in May of '07. With this plane I wanted to focus primarily on small size. I was still going for something lighter than my previous plane but I wanted to make an airplane that even I thought was small - a tall order considering I had been building micro r/c planes for year or two at this point. I chose a biplane design for this plane because it would allow me to keep a high wing area but keep the wing span small. The wing span on this plane is 2.75", the chord is 7/8", and the length is 3.75". The frame is all made of balsa wood and covered with OS film. Flight times were in the 4-5 minute range per charge. It is powered by a 3.2mm diameter brushed motor and a 1" propeller. The infrared receiver is capable of controlling the throttle and the rudder with a 7 step proportional control. The rudder is driven with a small electromagnetic actuator. The power source was a single cell 10mAh lithium polymer battery which can be recharged. Weight...

To start off my blog I would like to start by going over my first chain of wildly ambitious engineering projects - micro r/c planes... This was the first r/c plane that I built that weighed in at under 1 gram. I built this back in April of '07. It has a 5" wing span, 2" chord, and its about 6" long. The flight times were in the 4-5 minute range on a full charge. It was constructed of carbon fiber rod from 0.5mm to 0.25mm in diameter. The covering on the surfaces is called OS film and is made by DuPont. 'OS' stands for 'One Sided' because the film was so thin - maybe an internal department joke. It is on the order of 1 to 0.5 microns thick. The electronics consisted of a 10mAh Lithium Polymer battery (1S), a 3.2mm diameter brushed motor driving a 1" diameter propeller, an electromagnetic actuator to control the rudder, and an infrared receiver which was capable of throttle and rudder control. Here is a full breakdown of component weig...