Geek!

A big part of the FLG operations is conducted by the Geeks. They're responsible for creating all the groovy sound & lighting effects and fire effects triggers and sequences. Basically they do electronics and programming.

Monday nights at 7.30 is the Geek meeting. Members of the Geeks get together and discuss things like whether to use an R232 or R245 Bus. But they do also get involved in the arty side of things. For Xylophage they're responsible for the sound and light mushrooms.

These components are stand alone 14' high mushrooms that have sound activated lighting.

Lance began the meeting by demonstrating his prototype sound-to-lighting splitter that he had worked up using an arduino microcontroller. The sound signal is split into frequencies. Each frequency is linked to a light with a threshold setting to turn the light on or off eg. when the bass sounds, the red light flashes.

Lance's sound & light splitter

There has also been talk of making tactile switches such that when they are touched they cause light or sound to trigger. Tracey has been developing felted conductive fibre switches.

Prototype felt switch

Robin Hood and Beth have been working on paint effects for the underside of the mushroom. Since the mushrooms will have some UV light they are looking at incorporating glow-in-the-dark paint (without making it look like a sideshow Ghost Train!)

Trialling UV-responsive paint

There are a lot of switches to be made for Xylophage so I was enlisted and shown how to solder.

Trial soldering on a PCB

Eventually I graduated to loading and soldering a control board.

Completed Control Board

One day, this board will go to form part of the fire controllers.

Fire controller board (lower left) connected to power supply and cables to solenoid valves

Green Sand Casting III

Returning the next day to attempt to make this cast work several slight changes were made:

• The pattern was smoothed to remove a slight undercut;
• The cope was packed harder than previously; and,
• The packing was performed as several layers across the base of the cope rather than filling the void first then filling the rest of the cope.

This seemed to work.
Sprue and vent holes were added to allow the metal to flow to the now empty void and to act as risers, showing when the mould is full.

Adding a spue hole to the cope

Cutting a channel from the sprue to the pattern

Sprue hole and funnel sit atop a reassembled mould box

 Once the channels are cut the mould is reassembled taking extra care not to damage the protruding mould face. The mould is then ready to pour. Unfortunately we didn't use enough metal and the aluminium didn't completely fill the void. Oh well, better luck next time.

Incompletely poured button mushroom cap. The rim is supposed to form a circle

More Green Sand Casting

When I arrived at the shop Mark and Sue were beginning to assemble another box for casting. This time they were going to cast one of the mushrooms which will house the controller for the poofers.

Apart from the open cast we did the other day they hadn't used the cope and drag before, they hadn't packed such a large mould before, they hadn't cast such a deep concave mould before and they didn't know how it was going to work.

We went through the same process as before but this time added the cope. This goes on top of the drag. Baby powder is dusted across the face of the mould to enable the two halves to come apart cleanly. Then the cope is packed with sand. Turns out these boxes are so large we ran out of sand. and could only fill the cope about a third.

Packing the cope

What then needs to happen is the cope needs to be lifted and the pattern removed.
Unfortunately this happened!

The convex mould broke off about halfway

This took so long it was late in the day and no-one felt like packing another mould box. We resolved to try again tomorrow.

Meanwhile JDV decided he wanted to pull his G-nome Furnace out of mothballs. (So-called because it was used to make a large aluminium gnome!)
This furnace is big. It has a built in crucible and pours by means of a winch.

JDV operating his G-nome furnace

At least we got some ingots out of today.

Here, fix this!

Another Wednesday night and about 20 people show up for volunteer night. Maybe 5 or 6 of them have never been to the FLG before. Everyone introduces themselves by name and their favourite playground equipment (Vic, spinning egg thing). Then each department summarises recent progress and asks for volunteers. Mark from casting needs someone who can weld to fix the crucible holder which was run over by a forklift last year. I didn't exactly volunteer but somehow this task fell to me.

The crucible holder was bent, and didn't work. While trying to sort out what the problem was with the action I forced it too hard and the weld holding a tab to the frame broke. On closer inspection these welds were really badly made with no penetration.

Badly welded tab

I ground back the excess weld and then cut a groove into the still-attached tab. I then placed a root weld into the cut groove. This was topped off with a second fillet weld to join the two together.

The second tab I ground the end to 45 degrees and performed the same style of root weld and surface weld to secure it in place.

Miracle of miracles, when reassembled the action worked!

 

Poof!

The plumbers were at it again tonight; prototyping their mushroom section pilot light and poofers.

The main problem appeared to be the pilot light. Last week we tested putting the pilot light on the end of a 10' pole. This week we added the hood. Problem was, whenever the pilot light was placed too high up in the hood, the build-up of exhaust gases would snuff out the flame.

Pilot light

Spent a lot of the night trying various combinations but didn't successfully resolve the problem.

The sex-a-poof however was working fine. This is made up of a regulated gas supply which supplies and accumulator bottle that feeds six solenoid valves.

Sex-a-poof accumulator

These solenoid valves control the release of gas and are operated by an electrical switching mechanism.

Poofer control box

The gas then feeds to a nozzle that releases onto the pilot light resulting in an explosion of gas.

Nozzle set-up

Poof!

Green Sand Casting

Things have been pretty much the same for the last couple of days - cut bark shapes, roll bark shapes, hammer bark shapes, weld bark shapes...
But yesterday I saw some items on a bench that I recognised - a cope and drag for green sand casting.

Cope and Drag

Green Sand Casting is something I've read about but have not yet experimented with so I was pretty excited to find out that FLG have a casting division as well. I went over and had a chat with the guy messing with the boxes on the tables. He was a  chap by the name of Mark. He invited me to help him out with his casting experiment. Mark had just got these boxes made up. They are larger than any he'd previously used so he was going to do a test run.

He had settled on a toilet lid from which to cast. Apparently his teenage daughters keep breaking his!
Mark started by placing the toilet lid (or pattern) in the base of the drag and covering it with sand.

Pattern in base of drag

 The sand used to fill the drag is called green sand it's a mix of silica sand, clay and vegetable oil which makes the sand stick together and take the shape of any pattern that is pushed into it.
We filled the drag and tamped the sand down into the drag.

Tamping in the sand

When it was filled to the top we placed a board on the top and turned it over. Another board acts as a base plate and both sides are removable. Since this was Mark's first try with these tools, we ran out of enough sand to fill the cope. So Mark decided to go for an open cast instead. We moved the drag to a suitable casting location and levelled it as best we could. Then Mark drilled some screws into the pattern and jiggled it out to leave the void of a toilet seat lid.

Rapping the pattern

Simple open faced mould

 With the mould prepared Mark lit the furnace.

Mark lights the furnace

The furnace seems to be made out of an old gas bottle lined with fire bricks. It has a blower fan that has a propane gas feed just downstream. When the fan is on the propane/oxygen mix hits the inside of the furnace where it ignites and heats the crucible.

The Furnace

Mark filled the crucible with aluminium and placed it in the furnace before lighting it.

The Crucible

Once the aluminium had heated and was ready to pour we picked up the crucible and poured it into the open-face mould.

Cast aluminium toilet seat

Sunday at the FLG

So today is Sunday.

Get up and head down to the Boxshop for a day of fabrication.

Weekends are one of the busiest times for the FLG and this weekend was no exception. There were several groups of people clustered around performing various tasks.

The structure I had cut parts for the other day was being tacked into position when I arrived.

Uprights tacked into place for the third story

 This continued for the remainder of the day with the addition of the cross-pieces.

Tacking cross-pieces to the frame

But my job today was to mount the bark onto the substructure. While this may have been envisioned as a simple system it turns out it's probably not as quick or easy as was thought. Each strip of bark (after being cut, rolled and hammered) is mounted on the sub-structure frame by welding. Approximately 4 points of contact are needed which is not always easy because the bark strips are deformed and sit at odd angles and the substructure is a sweeping form made of compound curves. This means that each piece needs to be bashed and hammered into shape until it will sit into the spot you want to place it. It's also a two person job as it's too difficult to clamp the bark strips to the frame. You need someone to hold them in place while the other welds. I was working with Babs who showed me the ropes.
So we bashed and placed and welded for 8 hours and eventually covered one section of the stump with bark.

About 3 hours of bark cladding

8 hours later and the panel is covered