Another Blogger Blog

Hobby Motor Mount

2012-02-11T19:21:00.000+13:00

James and I are teaching the Engineering Foundation course again this year and one of the projects we're going to be doing is making a steam powered electrical generator.

The generator will be based on the steam turbine car which the students built earlier in the course.

The steam turbine car kit is from the University of Kwazulu Natal, in standard form they scuttle up and down the corridors of our engineering department while running on meths... Much to the displeasure of the cleaners.

We're going to be using a small DC hobby motor as the generator. Now i wanted something elegant for mounting the motors that would be compatible with the perforated plastic mechanical construction system we have for the class.

20 minutes with Sketchup and I came up with this:

The part was subsequently printed and here are two clamping the motor complete with a 3d printed pulley.

New Conduit Clamp for the Rapman

2012-02-11T13:36:00.001+13:00

For about a year now the Rapman has had a clamp holding the plastic conduit. The clamp was inserted into the original 10073 conduit mount plate. The plate is laser cut acrylic and on a recent trip to a secondary school I managed to smash it getting into the car.

I decided to design a part that took place of both the clamp and the mounting plate in one piece... 30 mins in google sketchup later and I had this:

Into the printer and 50 minutes later I installed the new part :)

Time Lapse Panning System:

2012-01-06T22:05:00.001+13:00

I'm shooting another video in the not too distant future which is going to feature a number of different time lapse scenes. After seeing a rather epic video by Jared Brandon I knew that some kind of motion system was needed:

Mt Ruapehu Timelapse from Jared Brandon Productions on Vimeo.

Staring blankly at the 3D Printer I had a brain wave: Sitting in the ceiling was my reflector telescope with a perfectly good equatorial mount... This mount allows the operator of the telescope to easily track a star or planet across the night sky as the earth rotates.

The brainwave involving the printer was to adapt the mount to take a DSLR camera for time lapses.

An hour with Google Sketchup and my vernier calipers I had a few parts drawn up.

The part on the right is an adapter plate the attaches a Manfrotto quick release adapter to the equatorial mount. The part on the left is a clamp for mounting a cordless drill motor (more on this later)

Then on to printing :-)

The adapter plate:

And the motor clamp:

Measure 200000000 times, draw, redraw and redraw meant that the parts bolted together without a hitch.

Mount with legs attached and a camera attached to the QR adapter:

So are you wondering what the cordless drill motor is for yet? The whole idea behind this system is that the camera can be moved a fraction of a degree in pan and or tilt between each of the hundreds of exposures required to make up a decent time lapse. Now I don't know about other photographers or engineers out there but I'm not doing that manually!

Enter the cordless drill motor: With the chuck it mounts onto the driveshaft of the pan head very easily. The clamp simply serves to take some of the motor's weight and to stop it from turning.

A test of the head with the camera in video mode:

Control electronics are in the works, likely to be based on the Arduino platform... Stay Tuned :-)

Engineering a Music Video?

2011-12-01T20:00:00.000+13:00

So despite being an electrical engineer and working full time at IRL and WelTec I rather enjoy playing in the entertainment industry:
Some past work includes Sleepeater and Walk Through Fire there are also a few other projects that I'm not that keen on talking about in a forum as public as this...

Anyways all these projects have involved me doing roles like special effects so I've never "directed" anything... Until now...

Enter Alphashift a band of guys who I know through work. In short they make music and I like messing about with cameras... So it was only natural to make a music video with them.

Here is where the "Music video for a band" stereotypes finish... You may think it's a little strange that an electrical engineer is directing a music video? Well things are going to get stranger still when I introduce some of the cast and crew:

Jonathan Otto: Director of Photography and Mechatronics Engineering student.
Mike Williams: Camera Operator, Brains and Automation Engineer.
Fred Glover: Bassist for Alphashift and Software Engineering student.
Innes Hutchison: Drummer for Alphashift and Civil Engineer.
Trevor Molloy: Guitarist for Alphashift and Automation Engineer.

Yes a slightly unusual group of people to be shooting a music video :) And here's the final result:

Repairing the RapMan 3D printer:

2011-09-03T19:57:00.000+12:00

So the RapMan started to misbehave a while ago... The parts being printed weren't very strong and the layers would separate with very little force.

With a bit of sleuthing I worked out the the 200k Ohm thermistor in the extruder nozzle was drifting out of tolerance in a big way.

A quick email off to BFB and Michael kindly sent me out four spare thermistors.

Let the rebuilding begin!

The extruder heater, nozzle and thermistor assembly are all held together by fire cement, this necessitated a little exhumation of the nozzle :)

I soaked the nozzle in hot water to soften the fire cement (I more than once very nearly took a swig of cementy water thinking it was coffee...)

After a little persuasion the cement was removed allowing the replacement of the thermistor :)

The printer has just this minute successfully completed a test print :D More to come.

Replacing the Magic Smoke

2011-06-06T17:09:00.000+12:00

So I've been doing a lot of work with the Rapman Printer lately. The present mission is to print a set of spare parts for a complete machine. Said parts are going to be assembled into a replicating mashup of a machine, stay tuned on that one :)

The upshot of it is that running the printer for extended periods caused a very well documented manufacturing fault in the electronics to rear it's head... There is no real protection for the ADC of the microcontroller reading the thermistor in the extruder.

Now when you have:
A machine made of insulating plastic brackets supporting a metal frame.
Hot molten plastic flowing through a conductive extruder nozzle.
And a fan continuously blowing air over the nozzle and work piece.

The above is a very good recipe for static electricity :) Whenever the relative humidity droppled below about 50% the machine would start crashing randomly. Throwing away three or four hours worth of printing was starting to get a little frustrating so I went in search of answers.

The recommended fix in the BFB forums is to run a steam humidifier next to the machine. I did try this and yes it worked...

However I have some fundamental engineering, ethical and financial issues with this as a fix:
The machine as it is uses about 50W and the humidifier uses another 250W, Ethically I have an issue with increasing the power consumption of a machine by 6x just because of a design flaw. From an engineering point of view a lot of humidity around electronics and bearing surfaces is never good. And it makes the room damp in winter!

So I started poking the machine with combination of zener diodes, capacitors and LEDs when something went pop. A wayward multimeter probe let the smoke out of the $25 extruder motor driver IC, bother. (feel free to insert non PC substitutions for bother which I may or may not have used at the time)

Above is the smoked 28pin T-SOP device sitting on my fingertip, it was removed with the judicious application of hot air from my SMD rework station.
The new IC was attached using solder paste, said rework station and a little swearing.

With the machine working again, my attention turned back to fixing the crashes.

On the right is a rather mediocre hand drawn circuit diagram on what I came up with to solve the problem.

The 220nF capacitor serves to soak up any high frequency noise and spikes while the 3.3V zener copes with overvoltages. The LED serves to increase the forward voltage and leakage resistance of the zener to a level that doesn't affect the temperature measurement accuracy. It also flashes whenever there is a decent static discharge to the thermistor :)

So far the machine has run for about 30 hours without any signs of crashing or glitches, long may it last.

Again on the right are the zener, capacitor and led soldered somewhat crudely to the extruder connector for now. Also of note in the picture, the extruder motor driver IC.

Distorted Gravity in Inception

2011-02-04T10:38:00.000+13:00

This is a short documentary about how the zero and distorted gravity sequences were done in the movie Inception.

I love the way that it's REAL... I'm reminded of reporter asking us how many layers were in Sleepeater to achieve the water effects. He was rather shocked when we told him there was only ONE :-D

The custom made slip rings are pretty cool, what they don't tell you in the video are what each ring does...
By the looks of it the five big rings on the right are the three phases, neutral and earth conductors which supply power to the while rotating rig.

The rings on the left carry data to the control system onboard the rotating rig, judging by the number of rings I would say they are using ethernet.

Slip rings are a lot more elegant than the solution used for the carnival ride in this video:

Freeze Motion Water Droplets

2011-01-31T11:32:00.000+13:00

James at Work spoke to me the other day about a clever lab idea involving a strobe light and a special kind of water pump.

The idea is that the pump squirts a stream of water droplets on a regular basis which are synchronised with the mains power frequency. A stroboscope is then shone on the stream of droplets which depending on the flash frequency will freeze or slow down the motion of the droplets.

Below is a video of a similar apparatus at one of MIT's museums:

After more sleuthing on the internet I found a web page owned by Professor Derin A. Sherman he has a demonstration using the same principles.

Here is the video from Professor Derin's lab demonstration:

My Lab Demo:

Initially I was unsure as to what sort of pump would be available here in New Zealand however that was short lived. Espresso coffee machines use a oscillatory piston pump to achieve the 10 to 15 bar extraction pressure required. My mate Hamish aka b45h4 has a dead coffee machine sitting in his garage just begging to be "hacked" :D

Thats all for now - check back in a couple of days for pics and videos.

Torque and Moments

2011-01-28T14:21:00.000+13:00

Introduction to Torque:

Introduction to Moments:

Engineering Mechanics Statics

2011-01-27T21:13:00.000+13:00

As promised here are a couple of youtube videos that may help you with the mechanics problems we're doing at present.

Introduction to Basic Trigonometry - Take a look at some of the other khanacademy videos while you're at it:

This one is part of a lecture series by IIT - It starts right from the beginning of mechanics:

Introduction to Vectors, Vector Addition and Multiplication:

Stamper - Assessment of Machine Condition:

2010-09-13T21:17:00.000+12:00

Video of the machine in operation:

Stamper - Index:

2010-09-13T15:18:00.000+12:00

This page is the index for all the documentation associated with the Stamper project.

Proposal:

Project Timeline:

Project Stamper:

2010-09-13T15:00:00.000+12:00

Primary Project Client: Wellington Institute of Technology

Manukau Institute of Technology Supervisor: Garry Robinson

Wellington Institute of Technology Supervisor: Mel Lock

Project Proposer: Patrick Herd 109 16873

Abstract:
The aim of this project is to upgrade a pneumatic stamping machine owned by WelTec: At present the machine is fitted with an ancient manual control system that is somewhat unreliable. The video below shows the operation of the machine in it's current state.

The new PLC control system will feature a touchscreen interface and will double as a lab teaching tool.

Objectives:

The impact ram machine in it's present configuration is used at open days to stamp key rings out of aluminium bar. The interlock and manual control system protecting the operator and audience are 1960s era brass pneumatic valves. The valve seals are worn out and sticky and as a consequence the machine is prone to being unreliable and on one occasion the ram fired with the protective guard open. Therefore the main aim of this project is to modernise the machine in order to ensure it is safe to be operated by non technically skilled staff at public events such as open days and careers expos.
As the control system will contain a Rockwell PLC and PanelView touch screen, the control cabinet must have the capability to be used for other purposes such as teaching or controlling experimental processes, when the impact ram is not in use for public events or teaching.

Specifications:

The stamper project consists of two distinct components:

Control Cabinet:
The control cabinet will be housed in an industrial polycarbonate enclosure and connect to the impact ram machine with a single DeviceNet or ethernet cable.

The control cabinet will house a Compact Logix PLC, Panelview touch screen and the associated hardware that will enable the use of both pieces of equipment for more than just controlling the machine. This will mean the control cabinet will be usable stand alone for lab teaching purposes.

Below is a picture courtesy of Garry Robinson at the Manukau Mechatronics Centre. The system IO will be made available to the user in a similar manner to the Mechatronics design using shrouded banana connectors.

Impact Ram Machine:

The impact ram machine in it's present configuration is shown below. The interlock and control system that protect the operator and audience are 1960s era brass pneumatic valves. The valve seals are worn out and sticky and as a consequence the machine is prone to being unreliable and on one occasion the ram fired with the protective guard open.

The pneumatic logic (shown below) will be replaced with modern solenoid valves and a Rockwell Point IO module. A new compressed air service unit will also be fitted.

As the machine must be capable of operation at events such as the careers expos which are held in locations where compressed air is not available the machine will be fitted with a small self contained compressor like the one below. The onboard compressor will allow the machine to operate in a self contained manner with only a connection to single phase 230v ac required.

Outcomes:

Assess the present condition of the machine.
Identify possible improvements.
Negotiate a suitable upgrade for the machine with WelTec BEngTech Programme director.
Liaise closely with WelTec BEngTech Programme director on progress and issues.
Remove outdated control system.
Effect necessary repairs to the machine.
Install new solenoid valves and Point IO module.
Install new air supply system suitable for portable operation.
Construct control cabinet in compliance with ASNZS3000
Ensure that control cabinet can be used for lab purposes.
Construct the program in RSLogix5000 to control the machine.
Construct the HMI to control the machine.
Documentation including operation of the machine and program function charts.

Methodology:

The control cabinet will be constructed first in order to allow the Point IO hardware to be tested as soon as it is ready. Design and layout of the cabinet will use CAD resources such as Solidworks whenever practical in order to minimise the chances of errors and allow as many details as possible to be shared between Metro Polytechnic members.

The control cabinet will be designed with equipment such as Festo Edutrainter and the Manukau Mechatronics Centre lab equipment in mind. This will ensure compatibility with the WelTec electropneunmatics training equipment built by Festo and also ensure maximum teaching benefit can be obtained from the financial expenditure.

Connections:
All the PLC IO will be brought out onto the top panel of the cabinet using shrouded banana sockets with the same colour code as the Festo Edutrainer equipment.
The USB sockets on the Panelview touch screen will be brought out using industrial panel mounting USB connectors.

The impact ram machine is in need of a lot more work:
The Norgren impact ram application notes have been consulted extensively in order to determine the most usable and safe combination of solenoid valves to use for the control of the ram.
All the pneumatic control valves will be effectively replaced by one Festo valve module containing two three port, two position solenoid valves. One valve is normally open (NO) and the other is normally closed (NC). This combination of valves has been chosen to ensure that the ram returns to it's retracted position and is incapable of firing in the event of an electrical power failure.

The pneumatic guard interlocks are to be replaced with an inductive proximity switch on one of the guide rods and an interlock switch which will lock the guard in the closed position when the ram firing. An optical fibre proximity switch will be fitted to the lower stamping die, this will detect whether an aluminium blank has been inserted. Preventing the machine from firing on an empty die and damaging it.

All the sensors and valves onboard the impact ram machine will be connected to a Rockwell Point IO module to allow the machine to be connected to the control cabinet via a single cable.

A new Festo compressed air service unit is to be fitted which will supply regulated and filtered compressed air. The new compressor will be fitted to the lower shelf and mounted on rubber bushes to isolate the vibration caused by the compressor from the rest of the machine.

Facilities and Resources Needed:
Most of the assembly, programming and the construction of the HMI will be carried out in the WelTec NE039 mechatronics lab. This lab has ample space and lighting to work on the project. Any machining and fabrication will be carried out in the WelTec mechanical engineering workshop and in the author's own home workshop when necessary.

The only specialist software required is the Rockwell Revs11 automation suite which is available where necessary.

Intellectual Property:
As the primary project client, WelTec will retain ownership of the completed equipment and all intellectual property associated with the project. However the design, PLC program and HMI will be available for sharing between the members of the Metro Polytechnic group.

Safety:
This project is safe in most respects, however there are some risks that need to be mitigated.

Noise:
Caused by the discharge of compressed air through valve exhaust ports and the mechanical operation of the machine. Risk to be minimised by wearing appropriate grade of hearing protection especially during the testing of the machine.

Compressed air:
Can cause eye damage directly or accelerate metal swarf and dust to high velocities when discharged. Risk to be minimised by wearing safety goggles at all times when working on the machine with the air supply energised.

High voltage:
230V AC wiring is necessary inside the control cabinet, This will be carried out in accordance with ASNZS3000 and will be inspected by a minimum of one qualified electrical inspector before the machine is energised for testing.

Mechanical Hazards:
The new 4" impact cylinder is capable of accelerating the stamping die to considerable speed. Therefore the ram must never be fired without the protective guard in place.

Time Planning:
The chart below shows the expected timeline and progress for the project, if the gantt chart doesn't load try refreshing the page a couple of times. Being embedded live the chart will be updated on a daily basis.

Budget:

Stamper - Project Timeline

2010-09-13T13:38:00.000+12:00

An Idea Starts to Take Shape...

2010-07-08T21:26:00.000+12:00

So I've been doing a bit of thinking lately... Ohhh dear.

I've always liked Theo Jansen's straight line motion creations, they're just too cool :-)

Stumbling across the Golden Mean built by the very cool people at http://www.fireishot.com/ about a year after seeing the equally cool creations at http://mechanicalspider.com/ caused a change in me...

The neurological gears started whirring, not very quickly at first but they were turning just the same.

Cue the end of March 2010 and the idea struck me at some ungodly hour... LETS BUILD A GIANT WETA!!!! It has to be BIG, Metal and Mechanical. Anyone else share the insanity?

SHIHAD - Sleepeater

2010-03-29T21:23:00.000+13:00

When Sam Peacocke approached me about doing some effects for a Shihad music video I had no idea how apt the title was going to turn out :-D

I was given a ten page PDF of how the video was to play out... It required a spinning shaking chair, water cannons, smoke machines and a wind cannon. For me it simply read: Lets make some cool stuff :-)

The pNuke:

This cannon resulted from my initial "more power Igor!" approach to the water cannon idea. The pNuke is a 9kg gas tank fitted with a 2" solenoid sprinkler valve. The tank is pressurised with an air compressor, activating the valve dumps the tank with quite some violence.

Thanks to: Greg at work for helping me out with the welding and James at Deeco for the valve.

Testing the pNuke with no nozzle:

The water is thrown even further when you fit the pNuke with a nozzle:

The following video shows why we decided to only use the pNuke as a wind machine... It's simply too violent when shooting water:

My Dad being pNuked:

Smoke Ring Cannon:
We did initially want to shoot smoke at everyone in the video... Software glitches filling our tent with smoke made us decide at about 1am on the saturday morning that smoke was a bad idea.

The Gentle Annie Water Guns:
These were used for generating the streams of water than fly behind and into each person as they spin on the chair.

A bank of 3/4" solenoid valves fill a bunch of polypipes with water and then use compressed air to "empty" them in a hurry.

Valve Bank:

The Gentle Annies required two different air supplies in order to achieve the desired effets. The pNuke was also supplied with regulated and filtered compressed air.

Air Supply Manifold:

The Final Result: www.sleepeater.co.nz/

Check back soon :) This is a work in progress...

Driving the RapMan rapid prototyper

2010-02-03T09:42:00.000+13:00

The following is a few pointers on driving the RapMan prototyper WelTec purchased in late 2009.

Destruction Manuals:

All the documentation is online in PDF format, the build manuals are 3d PDFs meaning they're best viewed with adobe reader. All manuals are on the Bits From Bytes download page. The version 3.0 manuals apply to our machine.

The build manuals should only be needed if something breaks.

Information on machine setup such as setting the Z axis height is all in the operations manual.

Skeinforge: The application that slices STL files into layers and generates the gCode tool paths.

The Skeinforge Wiki has information on how to install and configure skeinforge.

Skeinforge announcement and trouble shooting blog

Skeinforge settings for different plastics:

Polyactic Acid (PLA)

ABS

More to follow...

Building a Part:

Start by generating an STL file from your 3d CAD package of choice.

Open Skeinforge and select the material profile you want to use.

Click the Skeinforge button to open the file you wish to process.

Skeinforge will appear to "lock up" until is has finished generating the tool paths.

Once Skeinforge has finished there will be a YourFileName.bfb file in the directory the STL file was opened from.

Copy the .bfb file into the root directory of a FAT32 formatted SD card.

Insert SD card into the machine and refer to operation manual on how to run the file.

RapMan's first creation :D

2010-01-14T18:48:00.000+13:00

The plastic filament I ordered from Vik Olliver for the RapMan arrived today.

Sooooo tomorrow morning (Friday 15th of January) at 09:30 we're going to be doing the first build at work in Petone.

Let me know if anyone wants to drop in and take a look.

RapMan's Hello World!

2010-01-08T17:15:00.000+13:00

Today the incredible machine printed it's first ever test part :-D (the white squiggles on the build table)

Apart from a bit of a feed issue that you can see in the centre of the build table the machine seems to work OK.

I'll be taking the machine into work on monday if anyone wants to see it.

Time to order some ABS filament so we can start making stuff :-D

It's Alive MWAHAHA

2010-01-08T14:21:00.000+13:00

Yesterday I finished the construction of the extruder assembly.

I have now finished off the wiring and installed the extruder into the machine.

The machine is warming up for it's first test print :-D

Time to evict the spider and do some work :-D

2010-01-07T21:42:00.000+13:00

I've been neglecting to work on the RapMan a bit lately. As the photo above (woohoo macro lens) shows a baby orb web spider who decided that the machine looked like a nice place to build a home.

Once the spider was safely relocated to the outside world I started on the wiring:

Both the X and Y axes are now connected to the controller PCB, It makes cool whirry noises now :-D

Belts and a Build Surface

2009-12-27T22:05:00.000+13:00

Yesterday I fitted the drive belts that transmit the drive from the stepper motors to the X and Y axes.

Also fitted is the build table (clear plastic plate in the middle) which is moved by the Z axis. When the machine is running, parts are printed onto the build table layer by layer.

The Z axis lowers the build table by about 0.1mm after each layer of the part is completed.

Tomorrow: Starting on the wiring and the construction of the plastic extruder. Smoke testing is rapidly approaching :-D

Slidey Stuff

2009-12-26T21:44:00.000+13:00

The RapMan kit is now fitted with both X and Y axes.

Other items of interest:
The Y axis motor and drive shaft.
The Carrier for the extruder, mounted on the X axis.

Signs of Movement

2009-12-26T17:47:00.000+13:00

Yesterday (Yes WORK on Christmas day) I got the X and Y axis slides installed.

Installation of the bars that the linear bearings run on took much use of the eyechrometer. This is due to the bars needing to be perfectly parallel.

The beast is starting to get quite heavy... I may not be photographing it on the deck soon.

Due to the design of the clamping parts things keep slipping around from time to time. If the fastenings are tightened any more the magic CLICK comes out of the acrylic and I'm delayed by another 12 hours waiting for glue to dry. Hopefully it will stay square enough while building parts.

RapMan Squared :-D

2009-12-25T17:17:00.000+13:00

Well I have all the cross braces installed and I "think" all the sides are now square as they will ever be...

Several hours spent on the Bits From Bytes forums revealed that the supplied assembly jig is 2mm longer or shorter than it's supposed to be...
Needless to say short of creating a temporary black hole in order to adjust the laws of physics. Pythagoras' theorem is always going to apply...

Applying TLAR (That Looks About Right) my eyechrometer and mostly ignoring the jigs seems to have worked.

Another New Toy to Build!

2009-12-24T22:24:00.001+13:00

Firstly a little history:

A while ago the rapid prototyper at work let some of it's magical blue smoke out. While discussing the options around the round table, I suggested we look at the RepRap project.

About two weeks later I was emailed a shipping confirmation telling me that our shiny new RapMan kit from Bits from Bytes was on it's way.

Now that exams, pyrotechnics, a music video and visiting family are all over I've been able to get started on the build.

First Impressions:

My camera barfed while writing to it's memory card so I lost the unpacking pics :(

A lot of the laser cut acrylic parts have stress fractures in them :( I've only seen this happen after cleaning laser cut acrylic with xylene before.

After three days I now have a cubical structure assembled that is proving very difficult to get square.

Adding to the fun I managed to break a couple of the acrylic parts... Solvent welding the breaks with trichloroethelene works but it takes aaaaaaagggges to dry. Where did I hide that tube of super glue?

Walk Through Fire

2009-12-10T15:45:00.000+13:00

I was approached through a friend of mine about doing some special effects for an upcoming music video. My first thought was count me in!

Final product is here Making of shots etc are to follow as they're sorted through.

Hello World

2009-12-10T15:26:00.000+13:00

I know I know, it's a geeky way to kick of a blog...

Here over the coming months I am going to start documenting what keeps me busy in life. This is the start of my big scary portfolio.

Hope you all enjoy my musings and creations.

Patrick.... Is joining Web 2.0