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3D Printed Mechanical Pencil

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.


This is how the 3D printed mechanical pencil came to be. Luckily though, it actually works pretty well and has enough style to spare.  
This pencil has 4 separate parts and was printed fully assembled as shown in the image below. Its about 6" long and 1/2" in diameter at its maximum, not including the pocket clip. It takes standard 0.9mm lead and 7mm diameter erasers. Three extra pieces of lead can be stored behind the eraser. I would have liked to do a more common lead size like 0.7mm or 0.5mm but the feature sizes required to hold lead that small are very difficult to achieve even on high resolution printers. Its …
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3D Printed Tape Measure

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 and printed little test pieces here and there to validate the design. Right around the time I starting adding all the cutouts in the main body (for cleaning purposes), it sta…

3D Printed Dial Calipers

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 common place. 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 manufac…

Telepresence Robot

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 allowed pan/til…

4ch Plane with Retactable Landing Gear

This is the more 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 too cool. When it does get in the air it flies very slow. Although, it has enough thrust to get going …

Micro Servos

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 mea…

Sub Gram Ornithopter

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 are a blur and…