06 February 2011

DIY long recumbent

Another cabin fever project: a long-wheel base racer recumbent. This is based on Atomic Zombie's Marauder from his book, but with modifications as I go along. Why a long recumbent? Supposedly, above 20 mph or so, a rider is primarily limited by wind resistance. If you want to go faster, you must overcome that.

Unfortunately, recumbents (and their riders) usually look like this.


Atomic Zombie works hard to make recumbents look a little bit cooler...



I'm not sure I'll look much cooler than either of these guys, but fuck it... I want to ride fast!

The main frame is made from three pieces of 1"-square tubing. The front wheel is 20", and will be steered via rod (much like my Bakfiets), the rear is 26". The rear fork is made from an old fork (the seat stays) and some 1/2"-square tubing (the chain stays). The wheel-base is 6'10".

I've got a lot more work to do, but progress is coming along very well: I've got two wheels and cranks. Still need: steering, brakes, transmission.

This thing is so long it's hard to photograph. See the whole set on flickr.

Wheels on a stick.

Wheels on a stick

Bottom bracket

Joe with the Rear triangle.

Thank you Cyclab for letting me keep the intermediates and a lot of tools in your shop!

DIY Grow Lamp

We've had snow on the ground since the day after Christmas, and I'm getting a little bit of cabin fever. We're also getting exciting about the upcoming gardening season, and Daya started sprouting vegetables inside. When she started searching for indoor grow lamps online, I was disgusted by the prices. So, I walked into my workshop to see if I had any LEDs laying around.



LED Strip, DetailAnd that's when I remembered that I had LED strip.

I bought 3 meters of this at a great price while I was in India a year and a half ago. I thought I'd use it to bling-out my bike, but never got around to it. On later thought, glowing bikes are tacky. The grow lamp is a better use.

Each white rectangle is three LEDs: red, green and blue. The black rectangles are SMT resistors, 150 Ohm for the red and green channels, 330 Ohm for the blue channel. Each channel can be controlled independently to produce any color. The strip is printed on flexible circuit board with an adhesive backing. The strip can be cut at 3-LED increments. This stuff is pretty damn cool, and very easy to use in nearly anything.



Bottom view

I put the strips onto a piece of scrap wood grid that I found in the dumpster. I wired them together, and use an old laptop power supply to power them. Wiring requires a little bit of thought. A contiguous length of strip puts all of the LEDs in parallel. It's tempting to wire connect this directly to the power supply. However, the voltage drop of the lights is only about 0.7V. Putting 20V across that will draw a huge amount of current, and the LEDs will run hot. I chose instead to wire the strips in series. This gives as much light, but draws less current.



Action shot

The light is intentionally purple. I use only the red and blue channels, since those are (approximately) the frequencies of light that plants can use. Said another way; plants are green because green is the only color they don't absorb. Adding green would give a whiter color, but add nothing for the plants while burning more power.



Action shot

Underwriters Laboratories would not approve. Exposed soldered connections, no enclosure, and hand-wavy electrical engineering on an appliance that will be near water. Still, the power supply and LEDs run cool, and give intensely bright light.




We hang the lamp from a shelving unit in our living room. Underneath, we're sprouting Mustard Greens, Lettuce, Parsley, and Collards, and below that, a space heater to keep the seedlings warm. At least a month more before Jersey thaws and we can put them in the ground.

03 November 2010

Steinbeck quote

If I seem to be over-interested in junk, it is because I am, and I have a lot of it too -- half a garage full of bits and broken pieces. ... I do have a genuine and mostly miserly interest in worthless objects. My excuse is that in this era of planned obsolescence, when a thing breaks down I can usually find something in my collection to repair it -- a toilet, or a motor, or a lawn mower. But I guess the truth is that I simply like junk.


-- John Steinbeck, Travels With Charley

24 October 2010

Someone finally made the right kind of vacation planner.

If you're like me, you love traveling, but don't want to break the bank. The cost usually is more important than the destination. I know a few languages and I'd like to speak them. I want warm weather. I know a general time of travel. Where can I go?


I usually think about vacation in terms of "I want to go to a Spanish, French or English speaking nation in December, where the average daytime temperature is at least 62F, and with tickets for less than $1K." Kayak has made this nifty map application to answer that for me.

Thank you Kayak, this is brilliant.

26 September 2010

Maker Faire was Awesome

Two thoughts.

(1) If you're going to build a robot, make it a crowd pleaser:



(2) I'd saw my arm off for a thing-o-matic

16 July 2010

Photos from Guatemala

IMG_5147I just got back from a month long vacation in Guatemala. I've uploaded pictures.

If you just want highlights, check out Semuc Champey and Tikal.

11 July 2010

DIY Bakfiets

I don't have a car---not even a license---and so transportation is a problem for me. It wasn't a problem back in Charlottesville or in Brooklyn, since both cities offered walkable communities. But now that I live in Princeton, my grocery stores are far away. I use a bike for personal transport, but even then, I can only carry a small amount of groceries at a time. I need a better solution; I need a sport utility bike.

The spark that moved me into action was one of bike-machismo. My friend Sean-not-douche of the Cyclab asked me to help him build a tall bike. That went well, but I was embarrassed that we needed a pickup truck to transport my welder and tools to his shop. Why do we need to burn gas for a bike-geek activity!? It seemed wrong.

Sure, I could simply buy a trailer, but I don't really like trailers. I had built a trailer back in my Virginia days, but I didn't like how it affected the feel of the ride. The joint between the frame and the weight added an unsettling resonance to the ride, especially around corners. I wanted a design that offeres a more rigid ride.

The dutch have long ago perfected a design known as the Bakfiets ("box bike") for transporting cargo. These literally are the SUVs of Holland; Dutch moms even use these to carry their children to school. I thought about it, and the design seemed perfect for my needs. In short, the design is a two-wheel bicycle, with a large cargo platform between a 20" front wheel and the steering column.

IMG_4528 I ran off to lowes and bought a lot of 1" square steel tubing. The new steering column is made from 1-1/2" EMT conduit. The headset, fork and wheel were scavenged from a child's huffy. The cargo platform is made from two 1" tubes, one above the other, with 1/2" tubes supporting between them.
I didn't really measure anything---I eyeballed everything. I found out later that the angle between steering column and front half was important and incorrect. I would need to correct this later.


IMG_4529Next, my friend Hjalmar gave me a small, purple schwinn to serve as the rear half. I cut-off the headset and mitered it to fit the steering column, and added another 1" square tube from the bottom bracket. Alignment is important, but not critical. So, I used a string to aid alignment. I made a loop of string, joined by a rubber band for tension. I wrapped this around the dropouts and the headset, then tapped the steering column left or right until it was centered between the two lengths of string. Clamp, weld, and repeat until the frame is straight.


IMG_4543I achieved the steering using an offset arm. An old fork was cut and extended with a piece of plumber's pipe so it would span the steering column. At the end, I welded a bold at a 90-degree angle, and added a complementary bold on one tine of the fork. I added a length of rebar, which connects to these two bolts using univeral (aka ball) joints. I built it up, adding components and wheels, and took it for a test ride.

Honestly, the first time I tried it, it rode like crap. The bottom bracket was too low, and the pedals would strike the ground. It felt very unstable, and the rider would tire very quickly. But why? I can't say I knew enough about bicycle geometry---was the slope of the front wheel incorrect? Was it misaligned? I was lost.

Luckily, my friend Joe figured it out for me. I welded the front half to the steering column at a 90-degree angle, and the steering column met the top-tube at a 90-degree angle as well. However, the purple schwinn had a rising top tube. Effectively, the 90-degree angle caused the rear frame to tilt forward unnaturally and lowered the bottom bracket. The solution was to change the angle.

IMG_4575From what I had, the easiest solution was to cut just in front of the steering column, and then reattach at a more obtuse angle. This raises the bottom bracket, moves it forward of the seet, gives a comfortable slope to the steering column, and leveled the cargo platform. Indeed, this simple change made the bike much more comfortable.

Per Zach's suggesting, I added a triangular piece from the steering column to the cargo platform, for strength.

Next, I welded two 27"-long 1/2" square tubes perpendicular to the cargo platform. These will help to support the platform.


IMG_4583Once I had achieved a ridable frame, and could not forsee any major changes to geometry, I build a box out of scrap plywood I found in the dumpster. These three boards rest against the frame. I didn't have any hardware to attach the wood. I searched my junk pile, and found some scrap copper sheets, leftover from some roofers. I cut, bent, pierced these into brackets, and then screwed the frame tight against the frame. Copper is expensive---if you were buying it, I'd recommend you use sheet tin or steel.



IMG_4586Now the bike is done-ish. I can carry cargo. The next few things I'll do are: add sides to the box, add cable stops so I can shift gears, and also strip it all down and paint it. In the mean time, it's certainly strong enough to carry 8 bags of groceries, or a hundred-or-so pound of tools. Success.

But this is better than just a hack---this is a liberating technology. I want a life without gasoline yet without sacrificing quality of life. This machine gets me one step closer.
The whole set of photos is on flickr.