Friday, December 28, 2012

Project UberTutu

This project came about partly due to a slight obsession with things which emit many photons.
I had a string of digitally addressable LEDs from Adafruit bought because well... They were shiny! Enter Circillumina: An invite only rave dance party kind of thing... The perfect opportunity to play with glowwy lights.

Jez spinning his rather epic LED creation, the Mitochondrion

While throwing ideas around with Jillian and Rachel we decided that construction of some slightly out there costumes would be in order. Jillian is a stilt performer as one of her many many talents, she agreed to put on a bit of a stilt show at Circillumina 2 so a costume had to be created.
Rachel had a tutu in her collection of dress ups and I had the lights... Time to do something cool.

Rachel and Jillian started off by sewing the string of LEDs into the tutu whilst I ignored my nagging thoughts about how on earth this thing was going to be powered... The LEDs draw around 5W, not a small amount of power for something that has to run on batteries for several hours.

The LEDs are controlled by an Arduino which I soldered a JST connector directly to.

First test of UberTutu modeled by Rachel, Running Adafruit code.

As things were starting to come together, I turned attention back to power. I considered a number of different battery chemistries:
I have access to some pretty huge LiPo electric flight batteries, however I decided against this... The thought of strapping a battery which without warning can turn into an incendiary device to my friend did not appeal.

I have a Pag C6 video light: This has a 6V 8Ah NiCad battery pack with internal fusing. It's big, heavy, ugly and in a form factor that's not very sympathetic to being fitted to the female form. It is however safe. I used two silicon diodes in series with the battery to reduce the voltage a bit as the LEDs are designed to run from 5V.

I set about making a belt to house the battery that was comfortable and not too obtrusive.  I purchased a couple of metres of a while parka nylon from Global Fabrics in Wellington much to the amusement of the staff there.
After ten minutes with a pencil and paper I came up with a pattern. I cut the fabric out with a soldering iron in order to avoid the need to hem or fray stop the edges.

Unfortunately there aren't any more photos of the battery belt being made up as time was running short.

Jillian showing off the battery belt
Some flashier code was written and everything came together just in time for the night...

Thursday, December 27, 2012

Water Rocket Launch System

During my tenure at VUW I was in a role responsible for promoting the engineering school to potential students who were in their senior years of secondary school.

As an engineer I'm not much of a conventional marketing person, powerpoint slides and laser cut trinkets don't cut it for me. I also started playing with such toys as water rockets at a very early age... Enter the idea of running a challenge where engineering and school students are pitched against each other. Several emails later and my manager was convinced to go with the idea.

Now in it's simplest form a water rocket is nothing more than a bicycle tyre pump, a rubber stopper with a valve stem through it and a softdrink bottle. You fill the bottle say half with water insert the rubber stopper and pump in air.

Partially due to being prone to building silly contraptions that run on air and also due to restrictions imposed by the health and safety department. The idea of a joint pNuke and VUW branded water rocket launch system was conceived.

It had to be pneumatic as we already have a supply of air (the tyre pump) and so there would be no electrics to get wet.
It had to be black... In all seriousness, I build theatre and movie props... Anything not intended to be seen by the audience is matte black.

In the pneumatics stash I have a couple of HiRotor pneumatic actuators... Ridiculously oversized for this job but hey there's no chance of them breaking.

The actuators are sandwiched between two laser cut plywood plates to give the base sufficient rigidity.

Attached to the actuator shafts are plywood arms which support the two bottle retaining collars.

All the plywood components are soaked in watered down polyurethane, allowed to dry before a coat of flat black and a final coat of flat polyurethane.
The two collars lock onto the neck of the PET softdrink bottle above the flange on the neck, this ensures that the bottle is held in place very securely indeed.

The actuators are connected to the tyre pump after the bottle is pumped up. One firm pump is all that's required to pop them open.


Getting the air into the bottle proved more than a five minute task...
As the arms hold the neck of the bottle a good 100mm from the top plate, the bung had to be mounted on some form of standoff. Adding to the complexity is that the bottle is filled with air through the bung.
The final solution involved PVC pipe as a standoff, with a bit of trickery....
I set about creating what was in effect a hollow "bolt" with a 1/8th BSP fitting on one end to accept the air inlet.

This was made up from a modified tail fitting which I drilled to the inner diameter of the copper tubing. The hole was then counterbored to suit the outer diameter of the copper tube for a snug fit.
Pipe soldered into place
Drilled to suit the pipe i.d.

The other end of the copper tube has a short length of hollow M6 bolt silver soldered onto the end of it. The threads allow the bung, spacers and PVC pipe to all be clamped into place by one M6 Nyloc nut and washer.

In testing I realised that the arms don't always open together which can sometimes result in interesting launches... One arm releases the before the other, resulting in the bottle flying off at an odd angle. A temporary fix involving a pneumatic flow restrictor connected to the faster actuator was tried with some success. This will be properly remedied in a future version by use of a timing belt or gears between the two shafts.

A number of students, staff, teachers and friends all descended on Izard park in Wadestown to try out the platform and shoot rocket videos.

Kent from Onslow college was kind enough to bring their Casio 1200FPS camera along. Slow motion rocket take off video FTW!!

A really high speed (1200FPS) close up shot of the launch platform:

Last but not least: Some proof that perhaps pigs can fly... Megan's "Pigtoria" on her maiden flight. Trajectory is a little off due to the bottle falling foul of a hair dryer during construction.

Build photos for The rocket Launcher.
Some launch Freeze frames

Sunday, December 2, 2012

Industrial Pneumatic and Vacuum Plumbing 101

This little tutorial will take you through some of the methods used for pneumatic and vacuum plumbing in an industrial environment.

We will just be dealing with flexible tubing systems as used in most smaller industrial machines, large scale compressed air and vacuum distribution will not be discussed here.

The stuff that gets your moles of air from point A to point B. The most common materials are Polyurethane (PU), Nylon and Polyethylene (PE) My favourite is polyurethane as it is very flexible making it easy to fit into tight places.


All tubing that is manufactured in europe is metric with standard outside diameters being defined. Please for the sake of my sanity use metric components in your creations as much as possible. No, 6mm tube is NOT 1/4" There is a difference and the fittings are not interchangeable.

The most common "hobbyist sizes" are 4mm and 6mm. 4mm being suitable for control lines and smaller slow moving actuators while 6mm is more suited to supply lines or for bigger faster and scarier actuators.
Festo Pneumatic Tubing
SMC Pneumatic Tubing

Tubing can also be purchased pre formed into spirals to allow for movement.


If you are building something that requires multiple lines to one component but don't want to use cable ties it is possible to get multiway tubing. That is more than one tube is fused together.
SMC Flat Tubing

Dual tubing
It's all very well having tubes to do a plastic spaghetti impression with but how does one actually connect everything together?

One of the more common type of tubing connector is the pushfit, these seal the air in using an O-Ring and mechanically hold the tubing with a stainless steel collet. Pushing on the collet cap will retract the collet and allow the tubing to be released.

Now these fittings make assembling a circuit very quick and easy, the fact that connections can be made and changed so quickly allows one to "play" and generally mess about with valves, actuators and other components.
Festo QS Pneumatic Fittings
SMC Pneumatic Fittings

There are a heap of different fittings (way too many to list here) but to name a few.
T Connectors: Used to connect three tubes together,

 T Connectors are also available as a reducer, this allows a smaller diameter tube to be connected to a large tube very neatly.

All manner of threaded fittings are available too. Most are made of brass with the threads being treated with some kind of PTFE compound or tape to prevent leakage.

A 1/4 Inch Thread, 6mm tube fitting
A 1/8th Inch Thread 4mm tube fitting

The most common threaded fittings are British Standard Pipe or BSP
Now earlier it was mentioned that mixing imperial and metric tube and fittings was a bad idea... Well things may get a little confusing here as BSP threads are imperial. The most common sizes you are likely to encounter are 1/8" 1/4" and 3/8" taper threads.

Fittings are also available with Metric threads however these most often used for smaller sized connections (M5 and M6 being common sizes) Metric fittings are parallel threaded with a sealing gasket.

An M5 thread 4mm tube fitting

Reducing fittings allow one to change the diameter of tubing in some way, Say for example a very long air line is run in a larger diameter to reduce flow restriction. The tube size then can be reduced at the supply point to allow for flexibility or if the fitting size is limited.

A 6mm to 4mm reducer fitted to a 6mm T fitting

A valve fitted with a 6mm supply line
due to space constraints.
The lines to the ram are 10mm
A spaghetti of tubing and fittings
attached to control valves and rams.

A water rocket launch pad I built at VUW.

Where to get the stuff? Here in Wellington your best bets are:
Autoline Industrial in Petone: +64 4 570 0164
SMC Pneumatics in Petone
Norgren in Seaview

Sunday, September 9, 2012

New Home for a Light Shade

The time has come for parts of the Silly Light to find a new home... Mainly the ridiculous lamp shade as it's taking up a lot of space in the workshop.

I'm sure that there are many different uses for such an interesting creation... Much more exciting than what has been done with it here...

Here's the deal: If you can come up with a creative use for the lamp shade it's yours on the minor condition that I may ask to borrow it back from time to time.
Included will be all the chain, eyebolts and shackles which allow it to be hung from a single point.

Light fittings such as the street light or high bay are not included: However if you have a particularly cool idea for an installation involving the light shade then we can negotiate :-)

Please note: Said light shade is located in New Zealand... Moving it overseas is likely to be silly.
Also, should you wish to install this awesome piece of modern art in your home...

Don't have a suitable home? Then make a suggestion as to what should be done with this rather unique piece of plywood sculpture.

I suppose the other way to phrase the question is: Does anyone with a 6+ metre high lounge ceiling want a huge octagonal creation made of plywood?

Thursday, July 19, 2012

Building a Spreader Bar

My good friend Andrea has come up with a rather clever new aerial apparatus called Flyweight Chains involving a bundle of chain of similar mass to to the performer's body weight acting as a counterweight.
The chain is attached to a steel cable the other end of which is attached to the performer, the cable is then suspended from the ceiling of the venue by two pulleys. The result is the performer being almost weightless...

I started getting involved on the edge of the flyweight chains project around about the time of Andrea's debut performance at the Wellington Circus Trust Christmas Cabaret performance back in December 2011. My involvement at that stage was filming said debut performance:

Now the main issue with the system has been, the pulleys have to be rigged a very precise distance apart with the correct orientation to the audience. At cabaret this wasn't an issue however the requirements have limited the number of possible locations that the apparatus can be successfully be setup.

Andrea mentioned to me that  a spreader bar of approximately 1800mm in length would allow the apparatus to be rigged from a single suspension point... As a bonus the whole rig can also spin....

It was time to do some good old fashioned engineering; Jez, (rocket scientist) Andrea and myself set about doing some design work. That was after some rather NSFW trawling of the internet for all information possible on spreader bars, it would appear that such a piece of apparatus isn't just used for industrial lifting purposes...

After many many many different iterations, the design we can up with was to use plain and simple steel pipe for the bar with load rated eyes at the ends. Jez's rocket science method and my "use the scaffolding standards" both came up with a bar that would be good for approximately 2 tons in compression.

The cleanest way to buy load rated eyes off the shelf is to use either shouldered eye bolts OR eye nuts, we chose to go with eye bolts that would screw into threaded sockets in the bar. Said sockets are M20 threaded rod coupling nuts, modified slightly on a lathe and welded into the ends of the pipe.

Buying the coupling nuts turned out to be a lot cheaper than an equivalent piece of steel and cutting the required M20 internal thread.

The final result showing the pulleys, top cables and the free running steel cable.

The whole spreader bar and cable assembly was then proof tested at Steel and Tube... They issued the bar with a shiny test certificate proving that it had been tested to 500kg with no signs of distress.

Below is the creation in action at The Life You Imagined show in June 2012.

Also see: Andrea's blog post on this spreader bar.

Sunday, July 15, 2012

New Cannon

This creation is a new attachement built to go with the pNuke system of pneumatic mortars. These have been used for such fun as attempting to break the sound barrier and all kinds of effects in Shihad's Sleepeater.

Mike Bailey put me on to The Rock's Perfect Pie challenge... To build the world's greatest pie launcher. The PiNuke was the result....

Usually all pNuke plumbing is 50mm, now I wanted the pies to be shot intact complete with wrapper for effect. This required the new barrel to be approximately 100mm in diameter to fit a Big Ben pie whole.

A length of 100mm steel pipe was sourced along with a 50mm to 100mm bell reducer and a 50mm male BSP fitting.

The parts were Tig welded together in record time (there was only a week available for the competition)

A quick video was shot and edited the next day just in time to enter, turns out frozen pies at speed inflict rather a lot of damage to microwave ovens...

Fast forward a couple of weeks and I took the cannon away on holiday with me (weird I know) ZacJonathan and myself set about launching some nefariously fun projectiles such as fence posts with the cannon.

Fun with a cannon and cameras down on the farm
The cannon was strapped to an unsuspecting tree and much fun ensued... Of note: Dead leaves used as waddings and the flying soft drink bottles.

Saturday, April 28, 2012

Rapman Extruder Conduit Clamp

For a very long time now the Rapman's extruder conduit has been attached to the frame with a couple of velcro cable ties:

I decided finally that the cable ties were a bit too crude and set about designing something a little more elagent. Twenty minutes later I designed a clamp:
 Now it was only then I realised that the clamp needed an offset between the threaded rod and the conduit. So I had to throw away the nicely rounded clamp and start again.

Mark two was a little uglier - The part needs at least one flat face with no overhangs. That is, the face which will be laying down on the bed of the printer.

A couple of hours on the printer later and these were the result:

Still not perfect (I misread the protractor in my haste) but it clamps the conduit and the threaded rod OK. Mark three will be the correct angle :-)

If I say so myself this clamp goes pretty well with the first one made for this machine.