Misc

A vertical drill press

If there is one thing every engineer needs, it's a drill press. And I may be an engineer, but I did not have one. So I decided to make one. The thought pattern went something like this:

I have a pile of fairly crude model railway carriages that aren't being used. I should reuse their components and make my own carriages. I could cast the bodies. I need to make a master for the casting. I could design it on the computer and get it laser cut? No, that would take too long (1 month waiting period on laser cutting!) I could cut them out by hand? Mmmm I could, but it would be hard to get them perfect . If I had my own laser cutter I could cut them myself. Hmm… no, laser cutters are too expensive, and too dangerous. What if I had a machine that could cut them, but not using a laser? Michael does some googling … hmm, that machine would be called a CNC router. Does some more googling… and they can be very accurate and cut almost as ...

DIY earrings

Recently it was my six month anniversary with Rachel. She'd been dropping many "subtle" hints about all the things I should buy her to celebrate, but why buy when you can make?? So since jewellery featured so prominently in her wishlists I decided I'd make her some earrings. After tossing around a few ideas I happened across my old metal casting gear and half a white metal ingot, which gave me the idea of casting some earrings. And so with much vigor I launched into my next project.

Step one was to make a postitive to cast from. I dug out my trusty supply of blue plasticine and set to work. Working with a scalpel on an old mirror I made up positive and a box to hold the plaster.

Step two was to make the negative. I poured some plaster into the mold and then put it on a vibrating table to vibrate out any air bubbles. The plastic tray is to catch any spills.

A few hours later it ha...

Mr Blimp

We have a lot of helium here at the flat, a lot! As in two canisters worth. But anyway, I started my weekend by cleaning the garage and doing the washing, but by Saturday afternoon I was all done and had nothing to do. The thought of wasting an entire weekend without making something sent shivers through me, so for whatever reason I decided that I would make a cellphone controlled blimp. I suspect that decision probably had something to do with the package I'd just received from China, that contained a $6 bluetooth serial interface board. I was itching to use it!

A quick rummage around later and I found some spare LB1973M ICs, perfect for driving two small DC motors. Also in my DealExtreme package were a couple of mini solar toys which had some very small motors and gears, ideal for powering this thing.

A few hours later and I'd designed my circuit:

Based around an Arduino, i.e. an ATMega168. The power comes from a sma...

MMP

It is voting season here in New Zealand and I hope you'll excuse me while I talk a little bit about MMP. We have used the MMP system since 1993, however now we are faced with a choice on what voting system we would like to have. I have written a bit about MMP these last couple of days and am sharing my thoughts here.

A common complaint I have heard is "there are too many MPs in parliament, MMP sucks". Unfortunately this logic is a little flawed as every system in the referendum mandates 120 MPs in parliament, the committee in charge of the referendum has stated that this is not something that will change. In all the available voting system there will always be opposition MPs and all the bickering and infighting that brings. What changes is how fairly each voting system represents the desires of New Zealanders in the makeup of their parliament.

Another common suggestion I have heard is "NZ politics sucks, I want change". Firstly, what is it you wan...

High Altitude Balloon Experiments: Part 2

(Continued from part 1 )

My first test was a total success, but I had bigger plans. Happy that I could easily track my balloon from the land, and that the transmitter was powerful enough, I set about designing version 2 of my tracker.

Version 2 had one big improvement: a GPS receiver. Now I'd be able to track it's exact latitude, longitude, and altitude. Other changes included:

An Arduino Pro microcontroller module which is vastly more powerful than the PicAxe I had used previously. It is programmed in C++ and has plenty of storage and processing power. A 10v DC/DC converter that runs the transmitter at a higher voltage, in theory increasing its output power and hence range. A new lightweight PCB, made from flexible kapton material. A buzzer that beeps very loudly once every 15 seconds, so that once it had landed I might hear it even if I couldn't find it. This turned out to be a waste of power and space. Two 1.5v AAA E...