More CNC progress.

August 24th, 2016

I’ve been coming home and working on the CNC machine as well as at work in breaks. I am still waiting for parts to arrive from China before I can do too much more though.

I spent an evening making motor mounting brackets then when I was done realised I had made them all too small! I also realised I had made one part backwards so I redrilled some holes in the Z axis plate to make things right again. If anyone asks the holes are too add lightness like we do on old racing cars.

Today I cut up some angle aluminium (40 x 40 x 4mm) to make the gantry/X axis frame. I used the metal saw at work to cut the 45 degree angles and it works extremely well. I did the straight cuts at home by hand. This is them laid out to see how things will fit. I cut small brackets to bolt the corners together when the time comes. The gantry is just under 600mm high and I get 207mm of usable Z axis. That will be the absolute tallest thing I can 3D print.

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I laid the Z axis on top of the rails to check the motion and found a problem. Although everything moves smoothly I messed up some measurements and the X axis plate just hits the top of the frame at the sides so I will need to take them back to work and mill 10mm or so off the top of the angle that makes up the sides of the gantry. The X platform base needs to go over the top of the frame to get full sideways travel. If the base hits the frame the tool can’t get to the extremes of the X travel. I am using two bearings side by side to give me a wider base (at the expense of less travel) and am still waiting for the extra bearings to arrive.


You can see above how the top of the platform is flush with the top of the frame instead of running just over it.

My colleague Rod didn’t believe me you can drill through aluminium with a normal spade bit. I manage it fine. I just use a very slow speed in the drill press and lots of cutting fluid. Lately I have been using Inox as a cutting fluid (since I ran out of other stuff). It actually works very well. It has the advantage of being clear so you can see through it and see what you are drilling. It also smells nice!

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That was the hole in my new motor mount for the Z axis. I need shorter screws to mount the motor and also need to make a spacer to go between the plate and the bracket to get the motor height correct. The top of the gantry frame will need to be milled down a little to provide clearance for this bracket.

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You can see above the flexible coupling that links the stepper motor to the lead screw. The X and Y axis motor brackets will be the same. They are held by the same bolts that hold the lead screw bearing in place.

You can see my planning wasn’t precise. My drawings allowed me to see the basics would work and I knew I would have some tweaks to do as I actually started building. But I am trying to keep the design as simple as possible. I am confident the basic design is going to work now though. Lots of little things to work out still like where to mount limit switches and exactly the best way to make the base plate so it can be changed from 3D printing (which needs a heated bed) to laser cutting to machining.

Long overdue update.

August 18th, 2016

Well, it’s been a while since I wrote anything here. Not from lack of anything happening though! Lets see, I am still at Weta and still loving it. The things I get to work on and see are amazing. And mostly secret a lot of the time! Not sure what I am allowed to say I have worked on. Animatronics for films and various other things. I have to wait until these things come out then I can say what I did I guess. It’s great fun though and the stuff I am doing is a perfect match for my skill set. We do a lot of microcontroller stuff so I still do a lot of coding. Lots of hand making of things too. I knew one day all my silly projects over the years would be useful for something!

It’s going so well I have decided to give up on IT and just keep doing the animatronics thing for as long as that lasts. I sold my house in Auckland and bought a house here in Wellington in Miramar, close to work. Finally no mortgage which is great but I am on way less income so not a lot of money either! So much for my dream, no mortgage Orient Express trip (for now at least). But I earn enough to live comfortably so that’s all fine.

Been in my new house for about 4 months now and am just getting settled. I made this film to show people my new place in the world.

Sorry for the croaky voice, I had a bad cold.

So now I am almost settled I am thinking about getting back into my car projects. I have the Austin body to finish and the engine to build. And I would like to start on the Brooklands. I am now in contact with someone who has an original Brooklands and he is happy to help me with pictures and measurements of parts I am missing.  Mainly the engine/steering mounting brackets and some of the spring mounts and hangers. Will be good to get started on that. I have a parts list (for a Riley Nine, not a Brooklands) that I will go through and mark off what I have an figure out what I am missing.

I have the fireplace I am making but I will talk about that later. This post is about a new project, a laser cutter/3D printer/CNC type machine I am building.

In the film you can see a little project I was doing at work in my breaks and spare time. IT were throwing out a bunch of old PCs and parts. I managed to get a bunch of old DVD burners and pulled out the mechanisms and lasers. In a DVD burner the red laser is powerful to engrave things. This instructable inspired me and I basically did the same thing myself and made my own tiny laser engraver. I don’t have any need for one, we have several laser cutters at work I can use (we use them all the time) but I wanted to know how the machine worked. We also have at work a number of CNC machines they use for milling materials. They cut wood, metal and have an industrial robot arm used for cutting large blocks of polystyrene. I find them fascinating. I figured it would be fun to build my tiny machine to see how they work as the principles are the same as on a ‘real’ machine.


In the end I kept blowing up the red lasers from the DVD drives. They are very finicky and even with the correct current limited driver for some reason mine kept dying on me. In the end I bought a 500mW blue laser module from Aliexpress. It is more powerful and comes complete with driver, heatsink, fan and so on. Given how well that tiny machine (working area of 36mm by 36mm!) works I thought why not build a bigger machine. What I really want to make is a laser cutter that I can use to cut out paper gaskets for my vintage cars. My plan is to build up a library of gaskets that I can then cut out as needed. So I started thinking about a bigger machine, something that can cut a A4 sized sheet (210mm x 297 mm).

There a lot of machines and designs about online if you look. Or complete kits you can buy and build. I prefer working things out for myself. In the end I decided on a machine build from aluminium using lead screws to move the axes. These you can find on Aliexpress such as these ones. You can find everything on Aliexpress. I’ve been using it a lot lately!

As well as laser cutting I was thinking it would be interesting to see if I could mount a small spindle on it and do light CNC type things. Mainly engraving PCBs. That would be very handy. Failing that just being able to plot resist onto boards, manually etch them but then use the machine to drill the holes would be good. To do that you need a Z axis as well as X and Y. You need to be able to lift and lower the cutting tool or drill or pen or whatever it is you have mounted on the machine. Since I was starting to think about adding a Z axis I began to think well, why not add a decent height Z axis and add an extruder and use the machine as a 3D printer. Feature creep, it’s not just for software!

So my simple laser cutter has become something of a multipurpose machine. In the end I got two sets of 400mm rails/screws for the X and Y axis and a 300mm set for the Z. That gives me a useable area of just over an A4 sheet in X and Y and with about 200mm of Z. That is comparable (actually a little larger) than most of the DIY 3D printers around.

I drew up my design in Inkscape. Now Inkscape is a 2D drawing program. I guess really I should be learning how to use a 3D program which I will need to design 3D printed parts! I have started playing with DesignSpark which you can get free from RS. Inkscape works great for doing any 2D designs for laser cutting though. But I designed the machine in 2D using old fashioned 3 view plans. By grouping parts of the drawing I can shift the moving parts around to check the limits of the machine and so on. That actually worked rather well.

laser cutter zx axis template

To test parts of the design I laser cut some of the parts from 3mm scraps of MDF. That allowed me to see how things could all fit together. I was able to power up the stepper motor to see how well things would move. I did notice a little problem with the design but I will come back to that in a minute.


The main frame of the machine will be aluminium L section 40mm wide and 4mm thick. That will all be bolted together. The Y axis moves under a fixed gantry that holds the X axis. On the moving X axis is mounted the Z axis that moves up and down. The moving platforms for the axes are made from 3mm thick aluminium plate I scrounged from the scrap piles at work. One problem was how to cut it. To get it all nice I really should CNC cut it all. But I decided to do it all by hand. I cut the plate with a special blade in my jigsaw by hand. That worked very well. These days people are so quick to go for the modern ways but with patience and practice you can still do a lot of things by hand if you’re careful. After cutting I then linish the edges on my little home made linishing disc.

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The design problem I had was that there is a little unwanted movement in the platforms that run on the rails. This comes from two places, the lead screw nut and the rails and bearings themselves. The rail sets from Aliexpress come with one brass nut per screw. With the nut mounted into it’s aluminium block and that all threaded onto the screw there was a little bit of movement in it. I fixed this by ordering extra nuts and making what’s called an anti-backlash nut. Instead of one nut you have two nuts separated by a spring. I simply added extra threaded holes for the second nut on the aluminium mounting block and inserted a spring into the middle of the block around the lead screw that pushes against the second nut. The screws holding this nut on are not done up tight but instead are left with a gap so the nut can move a little. I loctite the screws in place.

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This seems to work very well although it adds extra friction to the whole mechanism. The stepper seems to easily overcome that though.

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The other source of movement is the bearing blocks that run on the rails. They are not very wide so I found you could get some movement on the rail. In practice this would show up as twist on the moving platform. To counter this I have ordered extra bearings and will double them up. This helps a lot although you do lose a little travel (the same amount as the width of the bearing) on the axes. Having the rails spaced as far apart as possible will also help eliminate twist.

This twisting is what I think will prevent the machine being a good CNC cutting machine. With laser cutting and 3D printing there is no side loading on the moving bits as the tool (i.e the laser or the extruder) isn’t actually touching the workpiece. As soon as you have a spinning cutting tool you are trying to move into a material you are adding a lot of extra force to the bits you are trying to move. I think this is when you’ll start noticing deficiencies in the machine. I think drilling will be possible as the force is all up and down but I am not sure how well it will go when sideways cutting. I can only try and see!

To help with making the aluminium parts I laser cut cardboard templates and used them as cutting and drilling guides. I hand drilled all the holes on the drill press.

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That last plate is the one on the Z axis. Since I want to mount different things on it (laser, extruder, pen, spindle, etc) I am putting in many threaded holes so I can attach whatever I like. I will talk very nicely to Jordan at work and see if I can use his parallel arm air driven tapping machine to tap all the holes. These machines are brilliant and I wish I could have had one when I was drilling my Austin 7 crankcase to helicoil the studs into it!

Once those are done I can start assembling the Z and X axis parts and it should start making more sense how this machine will work. I am very new to this and I am sure I am making mistakes and there are better ways to build such a machine but this is a learning exercise so that’s OK.

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I random orbit sand the plates after drilling rather than countersinking the holes. I prefer the clean, sharp look it gives and countersinking also reduces the thickness available to put threads into.

The electronics for the machine are on the way. The mini laser engraver uses an Arduino running GRBL. That works great and allowed me to get my head around G-Code and how all that works. Not to be confused with G-Spots, something most engineers never have to deal with.

I already have an extruder (the bit that melts the plastic filament for 3D printing) as well as a feeder that forces the filament into the extruder. These I got off eBay along with extra nozzles in different sizes.

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Still coming are the main electronics, which consists of an Arduino Mega and a RAMPS board, as well as limit switches, cables and also a heated bed. 3D printing is much harder than laser cutting hence the need for upgraded electronics and all sorts of other paraphenalia. A laser just needs simple on/off commands which you can do in G-Code. The 3D printer has extruders to control with heaters and temperature feedback as well as feeders and heated beds and goodness knows what else.

I should say here I have never actually used a 3D printer or had any interest in them. I am a metalworker really. I prefer making things by hand in real materials! But working where I do I can see the uses of 3D printing. We use it all the time. So understanding how that all works is a good idea I think and for me the best way to learn is to do things for myself. I don’t know what I will actually use it for when I have it! Maybe I can 3D print small patterns to then cast in aluminium? 3D printed christmas presents for everyone this year?

The laser cutting should be much more useful. I could buy a bigger laser although I have successfully cut gaskets with the 500mW one I have. Oh, that’s one thing to note. In NZ there are now restrictions on high powered laser pointers. You can’t easily buy them and if you try to import one you need special permission and a valid reason. This is due to idiots pointing them at planes and so on. So before I bought my burning laser I contacted the Ministry of Health(!) to make sure it was OK for me to import a laser module. Apparently it only applies to laser pointers specifically. Actual high powered laser modules are no problem whatsoever!

Anyway, that’s where I am up to at the moment. It’s a bit rambling sorry, am out of practice with this blogging business. I will keep documenting the machine as I go. It could be a total failure but it is good to be out in the garage again making things. I am just starting to settle again. It was quite a move!


Oh, and apologies for the bad photos. My old Canon Ixus camera died and I got a new one, a later model Canon thinking I could reuse the battery. But the bastards change the battery form factor between models so the batteries, even though they are actually the same, won’t fit the new model. And the new camera, an Ixus 175, is rubbish. The auto focus is really bad. Hence all the slightly out of focus photos. Next camera won’t be a Canon I think.

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November 29th, 2015

Yes, this place:


People who follow my car blog will know that’s where I am presently, and will be, for the next 5 months or so. I’ve been here about a month now. I am working at this place:


Weta Workshop.

The story basically goes like this (it’s quite long but this is a big thing!):

I’d just been made redundant from my last job. They ran out of money. Actually, worse than that, they had money pulled out by investors who obviously decided it wasn’t worth the risk. I don’t blame them. The company didn’t know who their potential customers were. That didn’t seem to matter though as they had no sales team to sell it anyway. And the marketing people didn’t seem to do any actual marketing (although once they did ask in company chat if anyone had any idea for cool social networking campaigns).

The product didn’t actually work that well either, being mainly a data store, but with no search functionality. I actually raised that once and was poo-poohed by the CEO, who said in the 5 years they’d been developing it no one had asked for a search function before, and the head of support, who said they didn’t need one since a user could simply go into the module they thought had the entry in it, order all the records by the time entered, then search through page by page (a page displayed 10 or so entries at a time) until you found the one you were looking for. This for a product that is meant to contain a lifetime (and that word is in the name of the company even) worth of data.

I knew the writing was on the wall when they decided to throw everything into making an iOS  app and hired a new team to do it at short notice. But apparently no one had read the Apple Developer guidelines (VERY important if you’re doing an iOS app). Any app sold through the Apple app store is either free or Apple gets a cut. And that cut is 30%.  You also can’t use a free app to lead people to a web app the users can pay for (which seemed to be their plan).

The app also used the Apple watch and made use of voice recognition. It never worked that well and they were trying to get something into the app store when the end came for most of us. Oh, they also made a nice video showing the product in use (faked!) but obviously hadn’t read the Apple guidelines for that either. Hint – if you’re showing Apple Watch functionality you shouldn’t be showing it on non Apple devices like Microsoft Surfaces!

Anyway, the upshot of all this was a bunch of us were given the chance of staying (for less money) or leaving. We had to decide, tell them what we wanted in one on one meetings, then management would decide who would stay and who would go. I’ve been through that before and it’s never a good situation. In my meeting I said I was definitely out, I didn’t even have to think about it.  In the end most of the development team was gone and 2/3rds of the test team leaving only the most junior to carry on. Apparently they would get the others, like support, to help with testing. I’ve seen that before and it always shows what management think of their testers when they say ‘anyone can help with testing’. And all the companies that say that end up failing.

Anyway, I was out and starting to think about a new job. I started putting a few feelers out. Now I.T. pays very well (I am thankful for that) but most of what you do in it is pretty pointless! Products that go no where, companies that fail, it all seems a bit unnecessary really. Makes job hunting hard since you of course have to go along to interviews and pretend you really believe in whatever niche thing the company is selling that they think will change the world (but in reality is just there to make someone money).  I have learnt over the years the most important thing is working somewhere with people and a team you like (and I did like the team at the last place) and actually liking the work you do. It can be hard knowing what either of those are going to be until after you start working there. I actually started interviewing and one place looked interesting, the team seemed good and I had heard good things about them but then this chance came up.

Thankfully since from the above rant it should be obvious I was feeling a bit jaded about the whole I.T. and software testing industry!

I’d just finished my Turing Welchman Bombe project and ended up sending a link of it to Richard Taylor at Weta. He’d previously seen my John Steed Puppet project and I knew he was interesting in things that people make. The CEO at a previous start-up I was at had forwarded him the link to Steed. Funnily enough I left that place to start at the last place and had left shortly before the entire dev/test team were let go from there. I didn’t know that was going to happen and hope no one there thinks I had any prior knowledge! It really was just luck I left when I did.

Anyway, Richard and I started chatting a bit and I mentioned, half jokingly, I was fed up with I.T. and had always thought one day I should apply to him for a job making stuff. I’d actually been on the Weta Cave tour last year and had talked to the guide about how did people get jobs there. They have a lot of people apply I imagine! Anyway making stuff is one of the things I like to do (see projects on the right there) and that’s obviously something they like to see. Richard said I should come to Wellington to see them, as soon as possible, they might have an opening for me.

I was down there in a shot! A slow shot since I took the train (much prefer the train to flying) but it was still all within a few days of our chat. I took Steed with me and had a sort of interview with Richard (you don’t get to take puppets to I.T. interviews although if I go back into it maybe I should try it!) then spent the afternoon looking around the workshop with the animatronics team lead. The next day they offered me a job doing animatronics working on a film project they are doing. I can’t say what it is, what they do is confidential of course, but there should be 5 or 6 months work. The film industry is fickle though and there are no guarantees, this was all explained to me, but for me the risk is minimal. And how could you say no! And I always have I.T. to fall back on.

I was in Wellington for the rest of the week so I started trying to find a place to live. The plan being to lock up my house and garages in Auckland and move here to Wellington for 6 months to see how things go. Everything came together beautifully. I got to see a fully furnished flat on The Terrace (in the middle of Wellington city) on the Saturday and went back to Auckland on Sunday to sort out how I was going to do every thing.  I was due to start at Weta the day after Labour Day, that gave me about a week! I got the flat so worked out what I would need to bring with me and sorted out sending that down. Very few people work for Weta Workshop as permanent employees. Due to the nature of the industry everyone works as an independent contractor. The work can come and go. I needed to provide my own tools (luckily I had nearly everything I needed). Animatronics is a mix of electronics and mechanics and increasingly I  guess, software, so I have everything I need already since those are all things I do for fun. My house I simply shut up, my parents being literally around the corner are looking after it for me. The plan is to try it for 6 months and see what happens!

I flew down, had a few days to settle in and started work! I’ll get to what that’s like in a bit.

First, my little flat. I own my own house in Auckland. It’s not big but it has all my toys, my TARDIS, my dust collection and all manner of other things as well as my two garages where I work on my cars. My new flat is tiny. I call it my Bacgelirvpaf. This is what my phone came up with when I tried texting ‘bachelor pad’ (badly) to my friend Penny and now the word has stuck. Interestingly, if you search for that in Google it doesn’t exist (errr, until the robots find this entry) but the Google auto correct does translate it back to Bachelor Pad. I think I just invented a new word!


My new little bacgelirvpaf is even smaller than my house. It is nice though. It’s in an older building full of small flats. Mine is on the second floor at the back of the building and I have outside access. It’s just three rooms and a small hallway. Kitchen, bathroom and living/bed room. Despite there being parking spaces there is no parking for this flat. So I have no car!


The main room is nice. I have doors so can shut off the kitchen and bathroom. I much prefer that to these modern ‘studio’ apartments where everything is one room really. The windows face west and overlook a small park built on top of the terrace motorway tunnel. It’s surprisingly quiet, I hear the odd noisy car on the motorway, but it’s actually quieter here than my house in Auckland. It’s gets all the afternoon sun and sitting on the bed all I see is the green of the park. It’s very restful!

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It was fully furnished although I had to buy the little table by the window (fold up plastic thing cheap from Bunnings). I bought my signed Steed picture (since Steed got me the job!) and my Brooklands memento I made after last years trip. The kitchen is full of comedy appliances. There is no oven, just a tiny toaster oven and a double hotplate. The fridge is decent thank goodness but the dishwasher and microwave are tiny. I don’t use the dishwasher much. It just doesn’t work well. It’s so small you can barely fit everything then when you do get it in there  it comes out dirty! I don’t have one in Auckland and don’t really like them (dish washing powder is nasty stuff) so I just use the sink! Takes a hell of a lot less time too!

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I bought the worlds tiniest crock-pot (12 dollars from the Warehouse – I got a bargain!)  and can actually make surprisingly good (but small) meals in it in that tiny oven.

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I should point out it doesn’t magically convert beef to chicken and that I only photograph my food in the privacy of my own home, I am not one of those freaks who do it in public! I also discovered you can get tiny gluten free pizza bases so I can make comedy sized pizza too (that was a boring one to see if it would work)!


I am actually eating far less which is probably a good thing. I also get more exercise as I am catching the bus to Miramar and back each day which is where the workshop is. The bus stops are only 5 minutes walk away either end but at the home end I am at nearly the highest part of the terrace which is on a ridge running above the city. There is a walkway down right over the road from the flat which is handy. But there are about 180 steps to travel!


It’s ok going down but coming up after a long day carrying my heavy laptop and shopping is a killer. I call it the Eiger, after The Eiger Sanction, as it will probably kill me. I am enjoying catching the bus again though, mainly because I get to read on it. I joined the library which is less than a 10 minute walk away. It’s one thing I missed when I was working from home, time to read. Public transport is perfect for that.

There was some interesting graffiti on that stairway but it’s gone now.


Wellington itself is a nice city. Very compact in the centre, you can walk everywhere. There is a New World Metro just down the road. Handy but expensive and it can get horrendously busy. There are other New Worlds either end, the one near Te Papa is very good and if needed I can get off the bus near there and walk home. There is also a VERY good fruit and veggie market near there on Sunday mornings.  There is a similar, smaller one, even closer to home.  Excellent quality fruit and veggies at very cheap prices. I get a whole weeks worth of vege and salad stuff for about $10. It does help that a decent stew in my little crock pot consists of only half a potato, half a carrot, half an onion, one small mushroom and what ever meat I want. I make salads for lunches and Weta provide free fruit which is nice.

The weather is odd in Wellington. I am pretty sure the Met service just make up the forecasts randomly.  It’s know for the wind and it can get very windy. If it happens to be raining too it can be a bit unpleasant. Sideways rain! And Wellington is not a place for umbrellas. But when it is a nice, calm day it is actually very nice! It can get chilly but I actually like that. I like hats and scarves and long coats so it actually suits me. I am known for wearing wool vests all though summer.

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The city itself is more relaxed than Auckland. And people make use of it. You see people relaxing all over the place. There are cool streets, good shops, places to sit and a very pleasant waterfront. I’ve lived in Auckland for most of 40 years and just never liked it much. Less so over the years. A few things are improving now. But it’s one of the things I have noticed. It’s a try hard type place. The sort of place where they go on a lot about being one of the world most desirable to live in cities (even those those sort of surveys are all bollocks). They’ll make a lot of noise and song and dance about it. Wellington strikes me as the kind of place that just quietly gets on with things.

It’s not all perfect though. Shops in the city close early and open late in the weekends. A bugger if you work long hours and need to get to some thing like a bank or post office. And I gave up on recycling. Apparently you need special bags from the council to put it out in. I haven’t worked out how to get them. I think what happens is they send them to house holds once a year. But I am in a flat and the previous tenants didn’t leave any or even have any. According to the council web site you can get more from the public libraries. So I asked at the city public library. They don’t have them because they are next door to the council service offices and you can get them there. I asked if they are open in the weekends. Nope, only during the week. And they shut at 5! So I gave up. This building seems to have it’s own collection and everyone else seems to put it in there so I do too. I doubt it’s being recycled though!

I have found people are friendlier here though. In shops especially, people are quite chatty. There are also tons of restaurants and bars and cafes. I am not much of a cafe person really. I don’t see the attraction of going somewhere that’s mad busy to be rushed and jostled and have to shout to talk. Same with pubs. I prefer quieter places these days. Rather just sit in the corner of a quiet pub with a beer and book to be honest! I actually miss The Crap House where I could go have a quiet beer and a moan about I.T. work with Dave and Ralph! I don’t have any drinking buddies here. I avoid Courtney Place (where the young people and tourists go – young girls pretending to be wearing skirts!) and am instead finding all the out of the way places. There are a few of them around.

Wellington does have a lot of small craft breweries. Although it is hard to tell a lot of the beers apart I find. And it is hard to find a good hand pulled pint sometimes. I have found a nice place just down the road that’s hidden a bit that good though. They have a couple of beers on the hand pumps. And I found I can get some Galbraiths bottled beer that the supermarket just down the road!


I haven’t seen too many old cars yet. The oldest is a 1953 Morris Minor that parks on The Terrace sometimes. I did see an MGB on a trip out to Petone once though. Nothing vintage though.


I am slowly settling in. Internet was a mission to get connected. That’s because I am unfortunately with Vodafone and they excel at incompetence. I arranged to have my connection from Ak moved. They said I would have to be home in the flat (why I wondered?) so I arranged for them to come round the same day I was home to take delivery of the things I had sent down. I had to take a day off work for that. I was looking out the window and actually saw the van turn up. The guy never came to the door though. I know that for certain as I was waiting for both him and the delivery men. I figured he’d done something in the building and that was all that he needed.

Next day, no Internet. Interacting with Vodafone support is a nightmare. They are one of these companies who think it is a good idea to offshore their support. I think it’s in the Philippines somewhere. If you are lucky you’ll get connected to someone speaking understandable English. Chances are you won’t. Either way when you do get though you have to go through the whole story with yet another new person every time. And chances are they’ll transfer you to someone else and you have to go through it all again! Eventually I was left the following voice mail.

You can read the rest of the saga in the YouTube description. Eventually it was sorted and luckily it wasn’t cut off. This time I rang back the NZ woman who had helped me sort it out directly and she checked and said it was all fine. Seems to be working now.

I have slowly been sorting out my hobbies. I had to choose what to bring with me. In the end I bought my film cameras (well, only 2 of them) and film developing gear, my microscope and my model making stuff. I had a mission trying to get my film negative scanner working on my laptop. The laptop is running Windows 10 and you just can’t get the scanner to work on it. The manufacturers know this and their suggestion is to just buy their latest scanner which will work even though the hardware is no better. Planned obsolescence, I hate that! In the end I did get it going by using it as a simple web camera with appropriate software (which in reality is all it is).

I have been doing model making. Plastic models and lately a little rubber band powered balsa and tissue one. I made a couple of those as a kid and find it quite relaxing now. I  sit at the window at my little table in the sun and do a little at a time. They are repainting and replacing the carpet in my flat in a month or so and will have to get a big drop cloth I think so there is no danger of dropping things onto new carpet!


I can take the model to the park behind the flat to see if it flies! I haven’t missed the garages too much yet although I would like to be building the Austin engine and starting on the Brooklands. Most of the time I have just been reading and listening to music and relaxing. I have an unlimited broadband connection so I just stream music all the time. Lots of classical stuff.  And watch a lot of films and old documentaries on YouTube. I am actually enjoying the lazy weekends! I miss my big computer a bit. Can’t really play FPS games on my laptop and I used to like a bit of Nazi killing. I have been playing some older adventure games from GOG though which are fun.

Electronics I am doing at work. That’s probably what most people want to know about. What am I doing at Weta and what is it like? I can only actually say so much! What we work on is confidential and you can’t take any photos in the workshop itself (they don’t even allow them on the tour). But I can give some general comments I guess.

In another post!

If you think it must be an amazing place to work, you’d be right!

Turing-Welchman Bombe completed.

October 4th, 2015

Well, it’s finally complete!


Probably what most people want to see is the Bombe in action so here we go.

For those who haven’t been following the whole project basically I reverse engineered then build my own desktop version of the Bletchley Park Bombe, the machine the British used to help solve the Enigma code during WW2.

Thanks again to John Harper, who lead the BP Bombe rebuild team and who answered some questions for me, James Grime, mathematician and Enigma Expert, Magnus Ekhall who was one of people behind the online Bombe simulator, Frank Carter, who wrote the BP Report 4 booklet, and Bletchley Park themselves who managed to find and send me a copy of the aforementioned report that is out of stock! Also the late Tony Sale who made available on his web site the US 6812th Division 1944 Bombe Report.

I started by making my own Enigma machine wristwatch because to understand the Bombe works you have to fully understand how Enigma works and how it was used operationally.


You can read about that here.

My Turing-Welchman Bombe machine makes use of some software I wrote in C++ running on a Raspberry Pi 2. I figured out for myself how the Bombe worked then wrote my own software version, initially in BASIC of all things to run on my homemade 6502 computer Orwell. With the general algorithm worked out I ported it to C++.

The Raspberry Pi 2 connects to an Arduino which then drives three stepper motors, via driver boards, to turn the three indicator drums on the front of the machine. These drums mimic the three indicators on the real Bombe. The Arduino reports back the position of the drums to the Pi as a series of pulses then the Pi can tell the drums when to stop. An LCD screen on the side of the machine mimics the original Bombe mechanical indicator unit as well as providing a basic user interface. Start and Stop button are provided on the front of the machine as on the real Bombe.

The machine runs in real time (although the next stop is pre-calculated) so a Bombe run should take the same amount of time as a real Bombe run at Bletchley Park.

The casing is steel tube brazed together and the panels are 0.8mm sheet steel finished in wrinkle black paint. All the wiring is cable laced together into bundles. The drums are 3/4 scale replicas I made at home from old sweet tins! All the parts for the hubs and drums are hand made with a small lathe and simple hand tools. The drum faces use dry transfer lettering (which is getting hard to find these days – mine came from a model railway shop)! The machine is totally self contained with it’s own power supply (a 12 volt SLA battery) so is portable, although it does weight 10kg.

Menus are loaded onto a USB thumb drive inserted into the back of the machine. I mainly run the same menu as used at BP but it does run other menus such as the test menus in the US Army report. I haven’t been able to get all of them to run though but then I can’t get them all to run on the online simulator either.

All the details of the build, software and so on are in previous posts but are some pictures of the finished thing.

General views:

IMG_4549  IMG_4536_1 IMG_4520_1 IMG_4511_1

Internal details:

IMG_4525_1 IMG_4526_1 IMG_4527_1

IMG_4529_1 IMG_4530_1 IMG_4524_1


IMG_4545_1 IMG_4547_1 IMG_4541_1

IMG_4543_1 IMG_4513_1 IMG_4514

Indicator unit:

IMG_4518_1 IMG_4531_1 IMG_4539_1

More details:

IMG_4526_1 IMG_4515_1 IMG_4517_1

I will make the code available to anyone who wants it but it’s not really much use to anyone without the actual unit. If you want to see it to see how my Bombe algorithm works though it’s not too hard to pick out the core functionality. You have to have a VERY good understanding of the Bombe and what it is doing to really understand how it works although the code itself isn’t hard to follow. If you want to see it just ask me. If there is enough interest I can package up the C++ code and the Arduino code (for driving the steppers) and post them here.

Below is an example of how my menu files look:

* This menu is used to demonstrate the recreated Bombe at Bletchley Park.
* This will generate two stops:
* DKX:Q (correct stop)
Rotors: 2, 5, 3
Reflector: B
Test register: G
Input voltage: A
U: 1i
E: 1o, 2i, 7o, 8in
G: 2o, 3i, 11o, 12i
R: 3o, 4i, 10o, 11i 
A: 4o, 5i
S: 5o, 6i, 13o
V: 6o, 7i
N: 8o
H: 9i 
Z: 9o, 10i 
L: 12o
W: 13i

Painting VHT wrinkle finish paint.

September 27th, 2015

This is a follow on from my Turing-Welchman Bombe project and shows how I painted the case panels in wrinkle finish paint. But this paint used in many other places, such as old car instrument panels, so I thought a film of how I do it would be useful.

I am tempted to turn off comments on that as I just know someone will say I am doing it all wrong (with no proof of their better way of course) but that is what works for me.

I am using VHT wrinkle finish paint as that’s the sort I can easily get here in NZ (Repco sells it). I get all the gas from the can then decant the paint out. It is very thin so can be sprayed as it from the gun, no thinning required.


The biggest problem I find is getting an even enough coat of paint. You need about 3 or 4 coats to get a nice, heavy build up but the real trick is getting it even. That is why I put the paint into a proper spray gun since I find it much easier to get a good coating using the gun rather than using the spray cans themselves. In the film I was having a little trouble with the gun (not enough paint in the pot) but even then I managed to get a good coverage. And yes, I nearly dropped it at one point!

You must avoid paint runs! Any runs in the paint will show up as a different, thicker wrinkle in the finished part. You can control the amount of wrinkle by how thick the coat is to some degree. I prefer a lesser wrinkle myself but that’s personal preference. Too thick and I find it look a bit overdone.

To make the paint wrinkle I use a hot air gun. I have a cheap 2000W one from Bunnings (I think I said NZ$30 but it looks like it is $40). I set it on the hottest setting. You just need to keep it moving to avoid burning the paint. Something that also works well is heating the back of a steel panel with wrinkle paint on the front. The other option is to put the piece out in the hot sun. That will work but I find it only works well if the whole piece is evenly illuminated. I get much better control with the air gun.

The paint then needs to be cured. If the piece is small enough I put it in my normal oven. There are some fumes released but I don’t find it too bad. I usually put them in with the oven set to 100C on Bake for an hour. On the can they say 93C for 1 hour but I know my oven temperature control is no where near that accurate the exact setting isn’t too important. Around 100C works.  Then I turn it off and let it cool slowly. If you are doing car engine parts, such as rocker covers, the heat of the engine should be enough to cure the paint. I would still bake those in the oven though as until the paint is baked it will be soft and if you attach the part with the paint uncured your fasteners are likely to ruin the finish.

If I can’t bake it because it is too big to fit in the oven, say a car instrument panel, then I leave them in the sun or a hot place (my metal garage works well in summer) for a week or so to let the paint cure.

I do find even with practice this is a hard thing to get absolutely perfect every time.


Here are a few other projects I have used this paint on:


Enigma Machine Watch


Orwell 6502 Computer


Austin 7 instrument panel.

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