Corbin's Treehouse - Corbin Dunn, Santa Cruz, CA
Plug Bug

Archive for 2010

Plug Bug: Rear Battery Box

Don’t forget about the original design: I did modify it slightly as I went along. I learned a lesson from the front box: add 1/8″ or so to the total length to avoid it from being too tight. I started the rear box by welding up the bottom piece. I also used this piece to figure out where it would attach to the frame. I ended up using the rear seat belt mounting points and also the side seat belt mounting points; those worked out perfect! The box is quite large, and just barely fits into the car. I... [read more]

Plug Bug: Front battery box fabrication

I’ve been working on fabricating the battery boxes out of 1/8″ steel angle iron and flat stock for the past two weeks. The first step was to strap them together to get an accurate measurement of the size of the batteries when as a group. I then went to SIMs metals in downtown San Jose and picked up some steel. I ended up needing more 1/8″ aluminum plate for the cells, and ordered another 4’x4′ piece from Reliance Metal Center up Union City, CA. I also needed some sheet metal, which I was going to get at SIMs but I... [read more]

Turner’s Cube

Tuner’s Cube. I made it for my dad for Christmas 2010. Aaron helped me over Thanksgiving break to figure out the details and did some machining on it too. It started out as a ~3.5″x3.5″ solid square piece of aluminum. We made a jig to hold it so it could be removed and place back in again at the same position but on a different edge. The rotary table on the mill was used to turn it out: Second half of the jig — this was Aaron’s idea, and it worked great. Just use a piece of mild steel with... [read more]

Metalwork: Wine Glass Rack

Here’s a wine glass rack I made for my dad’s wife, Karen. I made it a while ago, but it was a Christmas present, so I couldn’t post it till after the 25th. It is made out of 1/4″ diameter mild steel round stock. I bent each top piece by hand, freestyle around a little jig. I welded each one to the other one at the base. To cover up the welds, I wanted to curl some of the round stock around it; I tried to pre-bend it by hand, but that wasn’t working. Instead, I started by tacking the... [read more]

Plug Bug: Strapping Thundersky batteries together

Here’s how I strap the Thundersky batteries together. As previously mentioned, I bought the Mini Polyester Strapping Kit 5/8″ x .040″+seals + tools for $80 (plus shipping) on ebay. The pack of 4 (or 5) cells is squared with a regular square. Be sure to line up the terminals in the direction you want them. I ended up restrapping one cell again. Actually, I did it twice; I actually strapped it back together in the same configuration that I took it apart in (doubt!). Tape on the end pieces (1/8″ thick aluminum sheet). Twice I forgot to do this and... [read more]

Plug Bug: Weight Distribution

The unladen weight of the stock bug is 1807 lbs. The gross vehicle weight is 2645 lbs. Front axle load: 1080 lbs, rear: 1609 lbs. The front axle had the 10.6 gallon tank removed — when full, 10.6 gallons is about 66 pounds (6.25 pounds per gallon of gas). The engine, I’m guessing, was about 250 pounds (fairly easy to move with just two people). I probably removed an extra 100 pounds in other various components: rear seat, drum -> disc brakes, generator, smaller 12v battery, etc. So, my starting empty weight: about 1391 lbs, giving 1254 lbs of payload.... [read more]

Plug Bug: Battery Box Design

I did some research on what people have done for battery boxes. The cells need to be contained well so they don’t go flying around in the event of an accident. A few interesting posts I found: — some good pictures. Battery Boxes for the Adventure EV – a 1971 Land Rover, with nice boxes. I knew I wanted to make my boxes out of steel, similar to Travis’ bug. I wasn’t sure how thick of steel to use, so I asked on with this post. That also was a great way of seeing some other boxes that... [read more]

Plug Bug: Batteries Arrived!

I’m a little behind on the status of the project…I got the batteries on Dec 8th, but was really busy that week due to Louise’s show, Left of the North Pole. It was a pain getting the batteries; the guys at the warehouse had some miscommunication and I had to drive up to the place twice, wasting a bunch of gas in my truck and an hour+ of my time. Oh well! The bad news: they are bigger than I anticipated; I was hoping for 200ah cells in a “160ah case”. But, I’m making it work by removing the backseat... [read more]

Plug Bug: Gas Gap Sticker

My batteries are in California! I just need to have the guy call me to pick them up. I’m dying to get them and put the car together, but in the meantime here’s what I did. I’m going to make this into a sticker that goes inside the “gas” cap: Edit: A better png version. Email me for the photoshop file.

Plug Bug: Stereo

I wanted to have a good sound system in the car. I bought an Alpine stereo and a set of speakers. I was initially going to mount them in the doors, but I read that is bad idea for several reasons. For one, the door panels are rather weak, and a hard door slam could throw the speakers out. Second, the doors are made to get wet inside, and I don’t want the speakers to get water damage. Luckily, I ran across some “front speaker panels” on and ordered those. I bought 6.5″ component speakers and I was hoping... [read more]

Plug Bug: Auxillary 12 v Battery

A typical gas powered car has a large 12 volt battery mainly for the purpose of turning the engine over during starting. That usually takes a lot of amps to crank it over. Since my electric car won’t have that problem, I figure I can go with a significantly smaller battery. I heard people can get away with really small batteries, since the DC-DC converter will be doing most of the power providing, and the aux battery just provides some startup power to turn on the contactors and even out the draw for other accessories. I went with a Powersonic... [read more]


Tricycle From the back of Justin’s Shop (, Vancouver, BC, Canada. 2010.

Plug Bug: iPad mount

It’s raining today but I did add a cool option to my car. The iPad mount! I was originally going to make my own mount, but that would take days of machining time and would not probably work all that great. I decided to search for options and quickly found Ram Mounts. I bought the basic iPad mount and the long arm (along with 2 balls) for $40 or $50 (I forget now). I figured out where I wanted it and drilled a few holes under the dash. I then mounted the ball end with 3 M5 cap head bolts... [read more]

Plug Bug: Electric Ceramic Heater

I got my heater installed; I can test the fan and make sure the contactor comes on, but heat won’t come out until I actually have my battery pack installed. I cut a hole on the dash (opposite the emergency blinker sign, to the left of the ash tray) for the switch. I had to grind down the back area a little bit to make sure the contacts didn’t touch the frame and short anything out. The front 3-speed switch is then mounted to a little face plate that shows off/low/med/high. No picture (I forgot to take one). The fan... [read more]

Plug Bug: Wiring…and more wiring

I’m still waiting for batteries, but i’m getting a lot of the little details done. The car could be drivable if I actually had a battery pack. I can turn on the key and hear a satisfying “click” of the negative contactor closing. Hopefully the batteries are down in LA on a big boat that is about to come up to the Bay Area. I’m crossing my fingers hoping I get them before my week long thanksgiving vacation. Here’s a shot of a bunch of stuff wired up. I’m using 2/0 welding wire for the battery interconnects. I may upgrade... [read more]

Louise’s Twirlaween Rope Act

Louise did a performance at Poletential last Friday night. Poletential is a Pole Dancing Studio in Redwood City: I made the coffin last weekend for her performance and the whole show turned out pretty cool! Poletential is just starting to introduce aerial training to their repertoire and Louise’s act was a surprise announcement for it to get everyone excited about it. Here’s two versions of the video we took. There were a few other better cameras their and hopefully we can get their footage and check it out too. Click below to download the high quality version; 68 MB: Click... [read more]

Plug Bug: Wires and Hoses

More progress tonight. Here’s aluminum L angle pieces to mount the radiator on. I slotted the car with a 4.5″ angle grinder (plus a cut off wheel) to keep the L shape and make the mount stronger. Then there are stainless steel bolts to hold it together. The last one is only supported by one bolt, but it seems quite sturdy with all three supports: The reservoir tank with the pump mounted underneath. I later shortened the hose a bit: Mounted. The two mounting holes are also SS bolts since the back is exposed to the elements. The two are... [read more]

Plug Bug: Motor backing plate + Controller

The project is moving along slowly. I was pretty busy with other things last week and didn’t get much time to work on it. I wanted a 1/8″ sheet of aluminum to back the motor area and mount the controller to. I went to Sims Metals in San Jose last Friday, but they only had some odd thin pieces of aluminum and zero 1/8″ thick stuff. They recommended Reliance Metals in Union City, so I called them up on Monday and they said they did have 48×48″ sheets that they sell. So I drove the truck up on Tuesday; unfortunately,... [read more]

Plug Bug: Interface Module Installed

I worked on the bug a bit yesterday but didn’t get much done; things go slow! I ordered a Heater Kit from Canadian Electric Vehicles – — the easiest way to do a heater in a conversion is to get an inline water heater and just use the existing heating system in a traditional ICE car. The bugs are air cooled and don’t have any water heating system so a ceramic heater must be used. I was thinking about making my own by taking apart some cheap heating elements from Home Depot, creating a box to house it, and... [read more]

Plug Bug: Motor Installed

Last weekend was a big weekend for the project. My buddy Aaron, who has a lot of home-built EV experience and now works at Tesla came over to lend me a hand. He brought over a friend, Nate, who also works at Tesla. So two Tesla employees helping me put my car together; how cool is that? We set the adapter on the motor shaft, bolted on the lightened (and recently balanced) flywheel, and then bolted on the clutch pressure plate with the clutch disk inside: Then it was mated to the transmission. This is actually a picture from the... [read more]

Plug Bug: Wheel and Rim

A quarter shot of the bug with the painted wheels, white walls and new dome style hubcaps (from CIP1):

Plug Bug: Seats Upholstered

Not much to say, but I got a bunch of the rust off of the seats, fixed some broken parts, painted them and then put them back together with new foam. I got new seat covers and foam from and they look pretty nice. The foam for the seat backs is sort of awkward, and I may eventually try to redo it with some additional foam. I actually got some more foam and played around with it a bit, but I wasn’t quite happy with the results and just left it as-is. Seat back with burlap on: Rear seat... [read more]

Kika the Bengal Kitten

We got a new kitten! This is Kika, a marble colored Bengal. I miss Piper, our Siamese a lot. She has yet to come home. I told Louise I didn’t want a new kitten to replace Piper, but she said we could just have two cats if Piper comes home. So, we got Kika.

Purple KH 26 Unicycle

I recently spent some time powder coating some of my unicycles. Here’s my Kris Holm 26″ Mountain Unicycle with a Schlumpf geared hub, 2.3″ tire, and the KH handlebar: I powder coated the frame translucent purple, which first required a base of mock chrome: The pedals I also did metallic red, taking the bearings out before baking them. The spokes are also done; I taped them to a piece of aluminum that I cut out: and then clamped it to another piece of aluminum with a few c-clamps and wired them (at an angle) to the oven rack. This allowed... [read more]

Photography: Coker and Coke

Coker and Coke From the San Francisco Unicycle Tour, 2010

Plug Bug: Wheel Selection

My rims started out like this, with a bunch of rust on the sides and white painted part: I thought it wouldn’t be too hard to clean them up, but I was wrong! After some rust removing and stripping, I tried cleaning one up and almost decided it was pointless. There was just so much rust and it would take forever. I played around with photoshop dropping in the white wall tires with various rims that I could buy. Here are some EMPI 8 spoke GT wheels, white I like quite a bit, but don’t 100% go with the classic... [read more]

Vancouver Muni Weekend 2010

I had an awesome time at the “California” muni weekend, hosted in Vancouver, BC, Canada, by the VanUni unicycling club and dubbed the Vancouver Muni Weekend. It was announced via the Unicyclist forums. Here is a collection of pictures from Nathan Hoover on SmugMug. Here are some of the highlights that include me, and my notes so I can remember what I did and have one place to find all the links I’m interested in. Friday we did an informal ride at the North Shore (Mt Fromme) on a trail called Ladies Only. Tim Lee got a picture of how... [read more]

Plug Bug: Turning the flywheel

An electric motor doesn’t need a big flywheel to keep the engine running. It also doesn’t need the starter gear teeth around the edge. In fact, all it really has to do is engage with the clutch disc via the pressure plate. I’m not sure how beefy that needs to be, but I decided to take down a bit of the flywheel size on my old south bend lathe. Here’s the tranny, coupling adapter, and flywheel: I bolted the coupling adapter to the flywheel; it didn’t come with the right bolts, and I had bought some grade 5 bolts that... [read more]

Zip Line Information

I’ve had a few questions on where I got my zip line stuff. Here’s what I got: 1. Petzl Tandem Speed Pulley 30113 – $ 79.95 from, free shipping. 2. From I ordered the following. Note that they appear to be a front for “Fehr” –, and you could probably order directly from them too. 1 1/4″ x 250 ft 7×19 Cable $64.27 12 1/4″ Wire Rope Clip Galvanized $9.60 1 5/8″ x 6″ Eyebolt Galvanized $5.06 1 5/8″ x 15″ Eyebolt Galvanized $11.20 4 1/4″ Thimble Galvanized $0.96 1 3/4″ x 12″ E/J Turnbuckle Galv. $20.00... [read more]

Unicycle ride: Mr Toads and Hole in the Ground

Last weekend when my cat disappeared I was busy having fun doing some mountain unicycling. I might as well remember the good stuff. Saturday a group of us rode Mr Toads Wild Ride as a 13’ish mile shuttle. I think it was my fourth time riding this trail (hopefully by writing it on my blog I can keep track better). Here’s some info here on singletracks about the ride. It is one of my all time favorite rides in California. It is very taxing on the body, and tough to ride all the way up. This was my first time... [read more]

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