Dreamflight Invasion!

So, sleep patterns are screwed. I’m totally knackered. The list of repairs needed for R2 is rather long. Must mean I’ve been at a convention!

But not only a convention, I was also at a charity event for Dreamflight.

Dreamflight is a UK charity that changes young lives through taking children with a serious illness or disability, without their parents, on the holiday of a lifetime to Orlando, Florida.

Invasion 2018

The weekend actually started on Thursday morning with the usual game of tetris to fit everything in the car, followed by a fairly uneventful 5 hour drive down to London (well, Heathrow).

We got to the Renaissance hotel to discover the place had been taken over by police, blocking the way into the car park. Eventually we got to park up and discovered that it wasn’t because they’d heard there was a Starfury convention on with Eve Myles, but were there for the Royal Wedding going on that Friday.

R2 back at the Renaissance
R2 back at the Renaissance

After a quick checkin (done online, so only door keys needed) I dumped my luggage and went to unload R2. I hadn’t even got him out of the car when I had people coming up for photos! Of course, the hotel staff are used to him now and barely batted an eyelid when he came charging into the lobby.

We settled in for a chilled evening in the lobby with the other early bird convention attendees, with R2 entertaining the occasional visitor, before R2 went to bed (ie, the luggage store).

Friday was the typical lounging around the lobby waiting for people to arrive, and setting up for opening the convention. Whilst it was quite a quiet convention, the majority of the attendees were regular Starfury people, which always helps to make it a great weekend.

It was a cracking line up of guests from shows such as Dark Matter, Killjoys, Warehouse 13, and Torchwood. I went into the Meet and Greet that evening and got to chat with them all and I must say each one was absolutely awesome. All of them were up for a fun weekend and even came to party with us all a bit on the Saturday night.

Group shot with the guests of Invasion 2018
Group shot with the guests of Invasion 2018

I had the opportunity to get a photo with all the guests, tho of course I used my photo proxy instead and got what must be one of my all time favourite pictures for R2. Even better was that one of the guests, Jodelle, actually put a copy of the picture up on Instagram and said it was her favourite from the weekend! Eve didn’t seem to like being upstaged tho.

There are always guests who stand out at a convention that you would love to see again at another. In this case, every single one of them would be fantastic to have back, they were really that good!


R2 and Dreamflight
R2 and Dreamflight

Now, on top of this I had something that was actually better. I was already planning on taking R2 down to Heathrow for Invasion, but then discovered that there was a charity event on at the Terminal 5 Hilton, Dreamflight.

The 99th Garrison had been invited down to participate in the sendoff of the kids going on their special holiday on the Sunday morning, so seeing as I was in the area I put my name down. A few weeks later, the R2 Builders forum had a listing put up with an invite from the Rebel Legion/UKG for going to the Hilton on the Saturday too, to meet the kids as they turn up there from all corners of the country. So I thought, why not?

R2 and I got there on the Saturday a little early, unloaded, and went to meet the rest of the Legion. Plenty of Rebels there, and a few of the evil Empire.

The buses with the kids started showing up just after midday, with police escorts. They certainly know how to make them all feel special. The next few hours flew by with many a photo being taken. Besides us, there were also a lot of police, police dogs, and even a couple of police horses (tho they didn’t actually come into the hotel!).

Finally the last bus dropped off its passengers, and the kids were sent off to their rooms to get some rest before the day of travelling on the Sunday. R2 went to sleep (in the Hilton luggage store – he likes variety) and I went back to the Renaissance.

Tight squeeze, but so much fun!
Tight squeeze, but so much fun!

Sunday was an early start, off back to the Hilton to meet up with the 99th Garrison and to take the kids to the airport. It was actually arranged for R2 to ride on the bus to the airport, which was so much fun!

With one of my arms wrapped around a post, and the other around R2 to stop him rolling around, we set off. What I wasn’t expecting was for it to be a police escorted convoy! We had police on bikes riding ahead (with various cuddly toys strapped to the back of their bikes) to stop traffic and give us a none stop ride straight through to a hangar at Heathrow airport. They went all out to make the kids feel extra special, waving and saluting as the buses all went by.

We pulled up at the hangar and carefully offloaded R2. Inside it was all laid out for each of the groups of kids, with a military marching band, more police dogs, and a great view of the plane out of the big hangar doors.

Need a navigator?
Need a navigator?

R2 had a go at conducting the band, tho I think Kylo did a better job with his big glowing stick. The actual conductor started playing the Imperial March tho, which R2 took offense at and may have tried to run him over! None of that Dark Side stuff for him!

99th Garrison
99th Garrison

More photos, lots of smiles, and even a few requests for autographs (going to have to think of something regarding that). Finally the kids all got onto the plane and were sent off with lots of waving, despite the rain. We dragged ourselves to the buses and headed back to the hotel to dekit and relax.

I was actually expecting this weekend to be a bit heart wrenching, bearing in mind the reason for Dreamflight, but the atmosphere generated was electric and has given me such a buzz.

A few more pics here.


I’m finally home now. Starfury conventions are always fun and rewarding to work, but coupled with Dreamflight this has been such an awesome weekend. Thanks go out to 99th Garrison, Rebel Legion, and UKG for letting me come along with them. And of course, a massive shout out to the Dreamflight team. They all work so hard to organise and run this event, and whilst our work as part of the entertainment is finished, there are so many of them that are now looking after the kids in Florida, making sure they have the time of their life.

Looking forward to more charity events to raise money for next years flights, and hopefully I can make it back again to send them off.

Now back to R2 repairs!





Update and Roadmap

After a busy, busy May, June has been a bit more relaxing. May was filled with events, not just with R2, and pretty much drained my (and R2’s) batteries.

Got a few events coming up on the buildup to the big R2UK event in August, and a list of ideas for R2.

R2 Update

Until recently I was considering building another droid (as well as BB8), but with recent occurrences in my non-R2 life I’ve decided against it and have gone into a bit of a money saving mode. So, what does that mean? It means actually doing all the upgrades to R2 that I’ve been planning for ages and have all the kit for, but never got round to doing!

HP Twitch

I at least want to get the front HP twitching, and have done a quick model to mount the servos on and printed it out. Just need to work out the linkage ideas that will survive the little darlings pulling at it at every opportunity. These should run off the same system as the HP lights, and have i2c control

Modularise the code

Currently, adding new devices (lights, servos, etc.) involves writing a library and including that in the main code. I’d like to see if I can make each device a module which can be enabled and adds the commands dynamically to the REST API. Not sure how to do this yet, but part of the reason for doing my own control system was to learn some more difficult aspects of coding.

Knock/capacitive sensor

I want to actually utilise the REST API a bit more. One thought is a wifi knock or capacitive sensor installed in the dome that connects to R2’s hotspot to detect hands or whatever and play a sound via the API.

General brain improvements

After the Legoland event, I had to totally replace (and upgrade) R2’s brain. However, I only did the bare install and didn’t set up the extras in him such as the wifi hotspot, etc. I want to get this working properly to make debugging a lot easier.

Smoke generator

Another device for the dome, something to generate a load of smoke and that can be triggered via the API. This way I should be able to do a script to flap panels, play a sound, and release some smoke.

Theres loads of other general improvements to be made too, minor repairs and such like. I’ve also got a new set of foot shells to put on which should make swapping and maintaining the drives a lot easier than it is now.

 Another droid?

Yes, I know I said I’m not going to build another droid. By that I meant astromech. I’ll finish off BB8’s dome at some point, with some electronics in the eyes which I’ve already got. Got ideas to extend the normal setup of electronics to make him more dynamic.

My other thought was to produce a MSE droid. Something a bit fun and a lot cheaper than a full sized astromech. I also want to add features to it that I’ve not seen on other droids such as smoke, opening doors, maybe even a bit of AI for automated roving? Still 100% on the drawing board, and plenty of other non-astromech/droid related projects to do around the house, but it is something I’d like to do.

A lot easier to transport too. 😉

Apart from all that, got other Starfury events to help out at, and that nasty thing called Real Work to do to keep the money coming in.

Birmingham MCM, MOT, and Tier 2.

This weekend was R2’s first official outing with the UK R2 Builders. We were invited to attend Birmingham MCM Comic Con with the UK Garrison, an arm of the 501st cosplay group.

I loaded R2 into the car on Friday after work, and drove down to a hotel near the Birmingham NEC. Due to late booking of the hotel, I wasn’t really left much choice, and it showed.  Saturday was an early start so I tried for an early night so I was all set for a 7am start. That didn’t go quite to plan, nor did the hotel room shower. Still, fun and games at the hotel were just a blip on what promised to be a great weekend.

After driving round and getting lost in the maze that is the NEC, I finally saw a few other builders who were also trying to figure out where to go and its always better to be lost in a group than on your own.

Eventually we did find where to park, and where we were unloading and after a quick registration we started getting the droids into the building and set up on our stand.

First order of business was to get my droid a pass on his MOT. To be allowed at official events, and to get some Public Liability Insurance (you know, just incase I ‘accidentally’ run over a little darling who is poking R2 too much), R2 has to pass a club MOT and I have to show I can drive him. Its a really good idea, and adds a great level of professionalism to the whole event.

Thankfully, R2 passed, which meant he was free to roam around and entertain.

The Saturday of the event was extremely busy, with so many extra people showing up that we pretty much didn’t leave the stand. Not only that, but the UK Garrison couldn’t do their usual parade due to safety worries. Still, it didn’t really put a damper on things as people were constantly coming to the stand and being entertained by the droids.

It really is fantastic seeing the interactions that people of all ages have with R2. He isn’t just a remote controlled robot, he is an actual person to a lot of them, and I’m less of a driver and more of a puppeteer.

Then there are the Jawas. Damn things get everywhere!

Only kidding, the UK Garrison have a few Jawas in their midst, and they certainly get into character. It was so much fun getting R2 to play along with them and everyone around absolutely loved it. Even better when their wrangler started jangling keys to distract them and move them along. Bringing out the play in cosplay.

The day passed all too quickly, and we were soon packing up for the day and making our way back to our hotels. A few of us went out for a meal that night at a local hotel, and surprisingly the conversation wasn’t just about droids. Well, not quite anyway.

Another attempt at an early night and a bit more sleep was had, ready for a not quite so early morning on Sunday. The doors were opened for us at about 8:30am, and we wandered in to make sure the droids hadn’t got out over night.

Sunday was a little bit quieter, so a few of us managed to roam about the convention a bit more. I took R2 out on a number of jaunts through the day along the concourse infront of the halls where MCM was running. It was a great area to roll around, lots of people but not as packed as it was around the stalls and other areas.

It did take quite a long time to get from one end to the other, not because of the distance but because he was getting stopped every meter or so for photos, or to chat with me about him. R2 really does like his picture taken, much more so than I do.

We had a few more encounters with the Jawas, and some sneaky avoiding of imperial troops looking for droids but I managed to convince them that these weren’t the ones they were looking for. There was also a group of large feline types who seemed to take a great interest in R2 and got a little curious.

The UK Garrison do a troop on each day if possible, and thankfully they were able to do one on Sunday, not only that but R2 was allowed to join in. At 2pm sharp, we waited outside the UKG changing room, ready to tag onto the end of the parade. There were a lot of the UKG there, I thought the line coming out was never going to end, but it eventually did and R2 joined in. We did a basic loop of the event which took about 20 minutes, it was great fun even for someone like me who doesn’t like to be in the center of attention. Of course, R2 takes a lot of it off me.

So, you’d think that was the highlight of the weekend? Nope, as the event was drawing to an end, I noticed a load of rebel pilots gathering around at the stand next to us. Next thing I know, Anthony Daniels asked if he could borrow my droid for a photo shoot. Not really going to say no now, am I? He stuck around afterwards too and had a few other photos with some of the other droids too.

Sadly, the event drew to an end. We were rather tired by this point, me, the other builders, and even poor R2’s battery was starting to show some signs of tiredness. R2 got loaded back into my car (I really need a van!), and I set off on the 2 1/2 hour drive home. A quick take out once I was in, and then bed became too tempting.

Now that I’ve recovered however, I’m planning the next steps with R2. As well as the MOT to get insurance coverage, there is also a tier 2 option. Tier 2 means that your droid is effectively screen ready (maybe not screen accurate, R2 changes too much between the films and even between scenes in the same film!) and can be used in official Lucas/Disney functions.

This is another great thing about the R2 Builders club, we have tight bonds with Lucasfilm, and now Disney, and occasionally get asked to do some official events. Anyone who is active in the club and has a tier 2 droid can get the chance to do one of these events.

To this end, there is now a long list of issues on my github page that needs sorting to get tier 2 approval. After a weekend with other droids, and seeing what is possible, it has pushed my motivation up a level to improve the droid, and also given me direction. I’m going to stop going for the fancy stuff, and instead concentrate on getting R2 as solid as possible, and looking the part.

Python code to control an R2D2 (or other astromech) from a Raspberry Pi over i2c
Milestone: Tier 2
Issues: 2 open, 11 closed.

Make R2 more solid for shows, and aim for that Tier 2 classification (ready for LucasFilm)

So all in all, it was a really fun weekend. I don’t think the smile left my face during the entire event. I really can’t wait for the next big event with the builders.

Building a battery for R2 with 18650 cells

There are many options for a battery to power an astromech, from the tried and tested Sealed Lead-Acid, to the latest LiFePO4. This article will look at utilising the very common 18650 cells. These are used in power tools, laptops, even Tesla cars.

WARNING, this article will talk about opening old packs, harvesting their cells, soldering cells, spot welding cells, and lots of other things that could be quite dangerous.

Lithium cells of any type can heat up or burst into flames if mistreated. Only attempt the things in this article if you are entirely comfortable with any possible outcomes. Do other research, read other articles, the author accepts no responsibility for any injuries or death from the instructions given.

General theory

18650 refers to the size of the cells, 18mm x 65mm. They generally have a capacity between 1500 and 3500mAh. If you see anything saying 4000mAh or above, chances are its a scam. There are a lot of cells branded ultrafire that claim over 6000mAh capacity which is a total lie. Voltage ranges from 4.2v when full, to 3.2v when empty. These cells use Lithium-Ion technology, which is a lot safer than the Lithium Polymer that is used in many radio control devices. The drawbacks are that it has a much lower discharge rate. LiFePO4 are even safer, but are also more expensive. Li-Ion seems to be a middle ground, which is why it is used in so many places.

Generally, these cells are arranged in series/parallel to get the desired voltage and capacity. For example, a 24V battery is made of 6 cells in series. Extra capacity is added by putting more cells in parallel, so that if you use cells with 2500mAh capacity and want a 24V battery with 10Ah capacity, then you will use 4 rows of 6 cells, commonly written as 6s4p.

The current drain allowed on a battery is usually 1C, or 1*<capacity>, so in the same example 6s4p battery, you can have a maximum drain current of 10A. Doubling the battery up to be a 6s8p will give you 20Ah and a 20A potential drain. 1C is the safe limit using recycled cells. If you are using brand new cells then you may be able to get a higher current draw by checking the datasheet. For example a NCR18650B can draw 2C and a NCR18650PF can go up to 3C.



As mentioned above, 18650 cells are used in many places, and can generally be recycled. The best place I have found for second hand cells is from laptops or power tools. These battery packs can be cracked open and the cells removed. It is quite a labour intensive task, but saves a lot of money. You can pick up job lots of second hand cells from eBay, tho this is getting more expensive as more people are harvesting cells this way.

You have to force the two halves of the battery case apart, usually with a screwdriver or similar flat sharp object, and then separate the cells from the circuitry and cabling inside. Always wear heavy gloves, and take extra care when using a lot of force. Its easy to slip and damage yourself or the batteries. Also make sure to take care not to use the cells as a fulcrum as this will also damage the cell. Basically, be careful and take your time.

An Opus BT-C3100 18650 charger/tester

The drawback is that each cell is of unknown capacity and life, some cells may even be totally dead. They could already have been through a few thousand cycles. Each cell needs its capacity testing with a charger/tester such as the Opus BT-C3400. Of course, if you can ask friends and family for donations of old laptop batteries, you can save even more money. I managed to get a lot donated for free. Despite the drawbacks and amount of work required, you can end up with a battery for next to nothing that would cost a lot if you bought a ready made one. For example, I built a 24V 25Ah (approx) 6s11p for around £50 of cells, plus a few other bits.

The other option is to buy brand new cells in bulk. Either from Chinese sites such as aliexpress.com, or from other sites closer to home such as eu.nkon.nl. Chinese ones are generally a little cheaper, but you do have a long lead time and the risk they are counterfeit. A typical cell such as the NCR18650B (high capacity/average discharge rate) or NCR18650PF (medium capacity/high discharge rate) can be bought for approx £3 a cell.


As well as the actual cells, there are a couple of other essentials. These are cell spacers, which clip into various configurations to hold the cells in place, and allow air flow around them. You’ll also need nickel strip to connect all the cells together. Both of these items can be bought from aliexpress.com in bulk. If you are buying brand new batteries from NKON, they also sell nickel strips for a decent price when bought in batches of 10m.

Lastly, you’ll need battery connectors and a balance lead. The battery connector can be anything you wish, as long as it will take the current. The balance lead is a connector so you can make sure that all the series cells are at the same voltage. This is important so you don’t let one cell run down lower than the others, which will potentially damage the cell, and maybe the whole battery. You need one for the correct size of battery (eg, a 6s battery will need a 7 wire balance lead) which can be got again from aliexpress.com or ebay.

Constructing the battery

Once you have enough cells together, and all the other items, time for construction. The general process is:

  1. Sort the batteries into parallel sets with the same total capacity. The idea is to have them well balanced before you even start. You can use a site such as repackr.com to help with that
  2. Clip the cell spacers together in the required layout (eg 6×12 for a 6s12p), then lay the cells out. Each parallel set should be the same orientation (eg, negative to the top), but alternate them as you fill in the series set.
    The start of a 6s12p pack. Can see the parallel sets run down the picture, with the series sets alternating across
    The start of a 6s12p pack. Can see the parallel sets run down the picture, with the series sets alternating across


  3. Once you have all the batteries in place, clip the top of the frame into place
    Here is a small 3s5p pack, ready for the nickel strips
    Here is a small 3s5p pack, ready for the nickel strips


  4. Now its time to connect the parallel sets up. Using either a soldering iron, or a spot welder, connect strips along all the parallel sets. These are the ones that are all the same way up. What this does is create the capacity for battery pack. Be careful if soldering, don’t allow too much heat to build up on the cell, do it as quick as possible. You can get spot welders from aliexpress.com for around £200 that will do the job a lot better.""

    You can also get a device that will give you a full readout, just from plugging the balance connector in. They are only a few pounds from places like ebay. They will let you view the total voltage, each parallel set voltage, and also the max/min/dif between the cells.

    Balance capacity checker

    For the initial charge you will need to use a decent balance charger, such as an imax B6. These are generally for lipo batteries, used in radio controlled quad copters or planes. The benefit of a charger like this is that it will balance the cells out and has lots of monitoring and protection built in. Follow the instructions in the charger manual closely.


    Once charged, leave your pack for a while, even a month, testing the voltages periodically. If you have a dead cell, then it can manifest as one of the parallel sets slowly loosing charge. When this happens, you’ll have to dismantle the battery and retest all the cells.

    If you have the time, you can also do a full discharge test with the charger on the battery to get an accurate reading of its capacity. This will take a long time if you’ve made a big battery, depending on the charger you use. If you aren’t overly bothered about an accurate capacity test, just run the battery in the droid (or whatever other use) and monitor the voltage. Don’t let the voltage go down below 3*<number in series> (eg, a 6s should never be let to dip below 18v). To prolong the life of the battery, don’t even let it go that far. Full charge/discharge cycles are the worst case for wear on them, and will shorten the lifespan. I recommend discharging it to around 40-50%, at least on the first try.

    After the first discharge, check the balance of the cells again. Ideally there should be little difference between them in a fully functional battery pack. If there is significant difference (IMHO, 0.1v between the highest and lowest voltage) then you may have a bad cell somewhere. Do another balanced charge and discharge cycle and see if the same cell has troubles. If it does, rip it apart and try again.

    If the battery remains balanced, then you can actually use a none balance charger (cheaper, and usually higher current for rapid charging) for most charge cycles. Tho make sure it is balanced occasionally and no harm in doing a slow balanced charge once in a while.


    Using 18650 cells gives you great flexibility in not only the size (voltage and Ah), but also the shape. This example has shown creating standard blocks, but with some creativity you can make a battery that follows a certain shape (ie, follows the outer curve of an R2 unit’s interior). If you want to make use of recycled cells, then this is a very cheap option to get some very high capacity batteries built. Even buying brand new cells will still save you a lot of money.

    For example, I’m currently building a 6s12p pack using NCR18650B cells. I’m getting these for approx £3 a cell. That makes the total cost of cells £216, which gets me a 24V/40Ah capacity battery in a fairly small form factor that can give out nearly 80A (my droid barely pulls 10A at full speed!). I doubt I could fit enough SLA batteries in my droid to get that, and a similar capacity of LiFePO4 would set me back about £800. Even taking into account the cost of a spot welder (which can be used many times of course) its double the price.

    Further research

    One thing I haven’t covered in this article is a BMS. This is a Battery Management System makes sure nothing is going wrong with it, and will cut off the output when the battery gets too low. I’m still researching these myself, and will possibly mess with them on my next pack. IMHO, if you are keeping an eye on the battery voltage during use and doing periodic balance tests and charges, then a BMS is not necessary.

    Also note that capacity of the cells will drop over time, depending on number of cycles, how deeply they were charged/discharged, and how rapidly they were discharged. Take care of the battery, and it will last longer, drain it constantly at high current and it will be dead within a few hundred cycles.


R2 ventures out

The day finally arrived. I was going to show off R2 to the public. Up until this point, he’d not been out of the garage and only had a handful of visitors (including a few local kids… ‘have you got an R2D2 in your garage?!). I was a little nervous.


I’d only arrived home at about midnight the night before after having left a convention early (unheard of! Miss the survivors photo! What?!), not to mention I’d been in the convention hotel for 10 days by that point. After contacting the organiser of Morecambe Comic Con, he had said I could get there early to avoid the crowds and find a safe spot for R2. This meant being up, ready, loaded, and in Morecambe by 9am! One slight issue, well many issues with that time, but the main one being I hadn’t actually tried to load R2 into my car at all yet. I knew from measurements that he wouldn’t fit in in three legged mode, which was one of the reasons I’d built his sled. I also knew that the sled made it nice and easy to get him stood up in two leg mode. So all that was left was to see if the sled would hold up and get him into the car.

Success, R2D2 is in the car!

He fitted. Was a two person job unfortunately, but I have a few ideas to make it easier, and hopefully turn it into a single person job for the next event.


I managed to get to The Platform in Morecambe at about 8:55am, and hunted down the organiser. Thankfully Joy had followed me down, so helped me unload R2 infront of the Platform. Switching him from two leg mode to three leg isn’t too hard, 8 nuts to tighten on the shoulders, and some ankle locks to put in place on the feet. Unfortunately I had forgotten the spanner to tighten the nuts so had to get them as tight as possible by hand. Then came the fun of getting him in the building. The pavement surface outside was not conducive to operating an astromech. For something supposedly highly advanced, he doesn’t like to run on anything but a smooth surface. So, with a bit of lifting and a bit of dragging R2 entered the building. Thankfully once inside the floor was nice and smooth, perfect for R2 to have a wander.

R2D2 waiting for the crowds to turn up.As I brought him in and scouted out the place, I encountered a few handling problems. It appeared that I’d lost one of the shims from a foot which meant one of his drive wheels wasn’t getting the grip it should. This led to him veering off to the right all the time and at one point he encountered a stall and destroyed a lego figure! After apologising profusely, I found a corner to sit him in and waited for the crowds to appear.

Time for the fun

R2D2 found a nice place to stand.

Right about 10am, the doors opened for early access and I decided to move to the now closed fire escape. Up to this point, it had been open for people to bring their wares in for the stalls. Now it was a nice empty space to place R2.
Slowly the place started to fill up and R2 had his first visitors. The day started to just fly by after that. I just loved the reactions he was getting from people of all ages. It was so enjoyable to make people jump a little when he moved over to them, and I slowly got used to the controls and being able to give him a little personality. Up to this point, I’d only had a tiny space in my garage to move him, now I had a much larger area and could try a few different things. Kids seemed to love him, sometimes a little too much, but I’d already decided to work on the premise that if they managed to break something then I need to make it stronger. R2 should be a bit interactive. Tho there were times when I wished I had the cattle prod attachment on him. He got plenty of tugs on the HPs, and a few extra spins of the dome, and I managed not to trap any inquisitive fingers in the dome panels when they opened. One little girl however didn’t like him waving at her with a utility arm. I loved some of the cosplay at the event too, there were some fantastic costumes on show, including a friend of mine who came as Kylo Ren and hung around for pictures.

R2D2 playing nicely with Kylo
R2D2 playing nicely with Kylo

I tried to stay out of the way as much as possible as it breaks the magic if they see the wizard behind the curtain, or rather the guy holding the controller. When I was spotted, quite a few people were amused at the fact I was using a standard PS3 controller to operate him. A few people wanted to know how he worked, or more details about the build, which I was more than happy to supply. Possibly a bit too much information was given at times, but they were polite enough to keep smiling whilst I talked.

At one point, I was even interviewed by a reporter from the local newspaper. She asked a few questions and took a short video of R2 doing some spins, and uploaded it to their facebook page. The main site had an article released today, and I was mentioned and quoted in it.

I had a few friends come and visit me too, after all I had been talking about R2 so much over the last few years they wanted to actually come and see what I had been wittering on about. I’d like to apologise now for the nonstop talk of R2. Most who saw him agreed it was a worthwhile project!

Oh No, breakage!

Trying to hire R2D2 as an Auror
Trying to hire R2D2 as an Auror

There was an issue with the main dome drive, which I gave up trying to fix towards the end of the day. Thankfully noone seemed to notice that he wasn’t turning his head much. I was pleasantly surprised by the battery, which after a full day of entertaining was only just down to below half capacity. Also, taking him back to the car over the rough surface outside shook a few parts off him finally. I knew something would end up falling off, but they held on all day at least!

R2D2 gets the ladies...
R2D2 gets the ladies…


Already hoping to be at another event on Star Wars day, a May the Fourth event at Southport Vue cinema. Just need to get his MOT and my driving test, so he can be an official Builders Club droid. I’ll should have the door panels finished for the next event too.

I set a deadline!

This year has been a bit busy so far, and in February I realised I only had something like three free weekends to get R2 ready for his first outing, Morecambe Comic Con, a deadline I was determined to keep. Between conventions, work trips, and more conventions (including two on back to back weekends), I knew I had a lot of work to do in a short time. Thankfully, with a bit of organisation and a few late nights I finally managed to get him to a showable state. Not quite to the level I wanted, but close enough.

I utilised Github’s issue and project management tools to help organise myself, putting issues in as todo items, as well as logging things that I found were wrong as I went along. This actually helped quite a bit, and I’m going to endeavour to keep using it. I slowly managed to close off some of the items, and R2 was getting more and more complete. I managed to get the electronics and code to a level where it was stable and he wasn’t too fast to react. Had a few dicey moments when direction changes at high speed made him teeter on the edge of doing a faceplant.

And more bits were added, I got his skirt installed finally, after having bought it nearly a year ago. This however involved some fairly major dismantling of R2, which in turn meant I had to finally get the sled finished for him. Overall, I’m quite pleased with the sled, and it allowed me to lay him down gently and take his legs off to get into the base of the frame.

With the skirt all painted and in place, it was time to test the electronics with his new battery. Up to this point I’d been using a couple of SLA batteries, but these were heavy and didn’t fit in properly. Not to mention they were very low capacity. Over the last year I had been collecting old laptop batteries from various sources, and stripping them down to get the 18650 cells out of them. Once I’d tested the cells and selected the decent ones, I made a new battery pack (6s11p) which should provide 24V, with about 22Ah of capacity. A bit of metal folding and riveting, and R2 also had a battery box.

A quick reassembly, and he was back on all three wheels, ready for the final touches. However, time was getting very short indeed by this point. I had one weekend and a few evenings to get the panels on the doors, and to sort out a few other annoying little details. I’d had the idea of using sheet steel for the doors, but had trouble putting the correct curve into the metal to make it sit nicely in the door areas. If I can get this right, then the doors can be attached easily with magnets to the hinge areas, letting me remove them so I can still get the skin off if needs be. Without the right curve tho, this just didn’t work and looked rather poor. Unfortunately, with no time left I simple hot glued them in place, so that at least there was something there. There wasn’t even enough time to paint one of the panels, so was left bare. 

On my last evening to work on him, I made the decision to change the dome drive mechanism. I’d got a new, more powerful motor, but this gave me troubles with the friction drive in that the rubber ring was coming off. I did have a dome gear set, and decided to try that out (once I’d found it. The garage is a bit untidy). Turned out this was a bad idea. The motor gear is only a thin piece of aluminium, and you have to get it exactly in line with the equally thin main gear. With more time (and the correct cad file) I’ll laser cut a much thicker motor gear out of acrylic. This will make it both easier to mesh the two gears, and also a little quieter hopefully.

So, at about 1am I called him finished and went to bed. I was due to set off to a convention the next day in London. To make it even more complicated, there was another convention the weekend after in the same hotel. Rather than drive home, just to drive back again a couple of days later, I opted to stay down in London. I would’ve got another couple of evenings to do more work, but in the end I decided it was the better option.

All I had left to do was get to the convention

Slow but steady, or not…

It seems that xmas and new year is when all the part runs start. At least that is what it feels like to me, for all the parts I want.There has been a sudden rush in ordering things for R2 which means I nearly have everything I need to get him put together and mobile. The one part I’m still missing is the outer ankles, which I am hoping will be on a run soon. The last few cosmetic pieces I need are due soon too, such as utility arms and LDP. Progress whilst waiting for these parts has not been too bad, but I do keep coming across problems to work around. I guess that is the fun part tho.

On the electronics front, I managed to (I think) blow up my amplifier. I still need to hook it all up again and test it. I’ve a feeling that the switch I’ve got for main power isn’t rated high enough for the current that is going through. I’ve also decided to change the layout of everything, and install an actual touch screen inside R2 for the Raspberry Pi. This will give me the ability to control certain aspects of the software, and also at a pinch I can plug a usb keyboard and mouse in to do onsite programming whilst away at a convention or such like. I’m also currently waiting a Raspberry Pi v3 which will give R2’s brain a bit of a boost. Overall design hasn’t changed much, it’ll still all be controlled via i2c, but will also have wifi and 3g internet connectivity, turning R2 into a wireless hotspot! I will have to see how much the aluminium body affects the signal, but can always put an external antenna somewhere.

IMG_0298_CR2_embeddedI have more or less got the legs finished, and have done a test fit! Must say, they are looking rather good. All the parts slot nicely together and are pretty solid. Of course, I still have the problem of a lot of the screws and bolts being imperial (We’re part of the rebel alliance, don’t want any of that imperial rubbish!) rather than metric, so getting hold of replacements can be tough. This is more of a problem seeing as I’ve had some of these parts for quite a while and not only been moved around the office in the old house, but have moved to the new house and gone in and out of the garage, so some of the fastenings have been misplaced along the way.

I also decided to get one of the nice new hydro formed domes that are available. I was never too keen on the existing one that I had, and the new domes come with the mounting ring to fasten it to the body which meant one less thing I had to fabricate. A lot of the tutorials on the forums are geared around these domes too. Not only did I get a new dome, but I figured whilst I was doing that, I’d also upgrade all the things to go in the dome. This meant getting the ultimate hinges, aluminium holoprojectors, aluminium logic surrounds, aluminium eye, and even the fancy PSI holders. All this together gives me a pretty much top of the range dome for R2. It also means I can do a quick and dirty rebuild of the old dome at some point and create a different astromech.

IMG_0304_CR2_embedded IMG_0309_CR2_embedded IMG_0489_CR2_embedded
Which brings me more or less up to date. The dome is nearly finished, I just need to put a few final touches to it and tidy up the cabling inside. I even got the dome servos all hooked up and took a short video. I need to replace the arms on the servos with something a bit longer to get a bit more throw on them, but overall I’m pretty pleased.

Next step is to get to work on the body. I’ve got some of the ultimate hinges and have some installed already. Just need to fit the servos to them. I also need to trim down my data panel to fit it into the breadpan, but that shouldn’t be too much trouble. The one part I’m having issues with is the charge bay breadpan, it just doesn’t want to fit in properly. I may have to resort to some pretty hefty modifications on it.



I’ve given myself a deadline of June to get him mobile, but that depends on when part runs happen. Fingers crossed the outer ankle run starts soon.

More power!

11934535_10156061505195316_3190924556943319116_oIts been a long time since an update, but we moved house at the start of the year and things have been hectic. At least, thats my excuse and I’m sticking to it! I have been making progress with R2 in the last couple of months, doing a lot of work on his brain for starters, and painting various parts.

Code wise, there has been a couple of fairly drastic rewrites since my last update. The interface is a REST API, which sends commands to various modules as before. I’ve added a scripting module now, so that scripts or loops can be initiated such as random sounds, or a dance routine. The servo module had to have a major rewrite too as I discovered that I could only control one servo at once and had to wait for that to finish before another command could be sent. That wasn’t much good! I’ve also written the first of the actual controller interfaces (not counting a simple web one for testing), R2 can now be controlled from a PS3 controller. Button combos are read in from a csv file to trigger certain effects or scripts. Lastly, R2 now has a voice, and can play any mp3 stored in a directory, including selecting random ones from a list of types. Next step is to get either the Pi or the A la mode Arduino to control the speed controllers. I don’t want to run them off the Adafruit i2c servo controller for safety, I’d rather drive them directly and have some form of watchdog to make sure R2 doesn’t go on a rampage. All the code is still available on GitHub under my user, dpoulson

The PDU also needed a rethink, not least of all because of the amount of current it needed. The setup now has feeds directly to the speed controllers, with relays on the output from them to the motors so I can break the circuit if needs be. These relays will automatically turn off if the battery is disconnected so that any pushing of R2 will not feedback into the speed controllers and fry them. The relays will also be controlled from GPIO pins on the Raspberry Pi so I can disconnect them via an API call. I’ll also have an input for a kill switch that will have to be permanently on if any of the motors are to be powered, possibly using a transmitter in a replica droid caller or hilt of a light saber. I’ve a base idea for the new relay controls:

Powerswitch The relays I’ve found are Omron G4A-1EA, which have the benefit of the switched load being on spade connectors on the top, rather than through PCB traces, which when I did the calculations would need to be massive to support the potential current running through them. This allows me to make a simple PCB with the controller circuit, and hook the 24V battery up to it to power the coils. If the battery is removed, the coils turn off and the circuits are broken. No fried speed controllers.

The 24V connection will probably go through the fuse box I’ve installed, with a hefty fuse. The makers of the speed controllers don’t actually recommend a fuse but I’ve seen a few comments saying a 60+A fuse can’t be a bad idea, just in case!

The battery will connect directly to the center contacts of a DPDT switch, with the fuse box on one side, and the charger connection on the other. This will allow charging the batteries without taking them out of the droid. Not sure if this is best practice or not, needs more research. Currently they are just a pair of 12V SLA batteries that I had, connected in series to give the full 24V.

I’m hoping to get some time either this weekend or next, to hook up the motors, speed controllers, and battery, to test them out and get an idea of potential current draw. They’ll be controlled with a standard RC transmitter/receiver for now. If I can get the legs onto R2 he may even be drivable by xmas.

Fingers crossed!

R2D2 is all skin and bones

I recently got a nice parcel turn up at my door; my COM8B R2D2 frame. COM8 frames are one of the standard frames that are used by the R2 Builders club, with a number of different variations. I got the B, or budget, frame which is just a bare bones with nothing fancy to it.

A parcel is here Mmmm, packing peanuts! Shiny Aluminium






The frame is really easy to assemble, as it is well machined and comes with some easy to follow instructions. It took less than an hour to put it all together, and at the end of it I had a nice looking frame. It also comes with handy mounting points for electronics. Some of the other features include a nice bracket for the dome motor, spring loaded to ensure a decent connection between the drive wheel or cog, and the dome. I’m just waiting for the charge bay panel to come through.

Assembled R2D2 frame

The next step was to work on the skins. I got these at the same time as I got the dome, and its been sitting gathering dust all this time. So far I’ve removed a few of the panels from the inner skins, but still have a lot more to cut out. Some of the seams are very thin, too thin for a hacksaw, so I have to be very careful with the cutting out. I may have to resort to the dremel to do these parts, but I’m loathe to do that as it could end up being very messy. There are some panels to remove from the front inner skin that aren’t pre-scored much like some of the inner dome was, so these need to be marked out and cut.

Skin test fit

For now I have drilled some of the mounting holes to attach the inner skin to the frame to give it a test fit. There are small 2mm gaps where the skins don’t meet, but from looking at other photos this is fairly standard and once the legs are on they hopefully won’t be noticed. I may end up filling them in a bit.

Test fit of front skins, both layers. Lots to cut out on both layers.

Test fit of inner rear skin. Need to cut out the rear door.

I’m just waiting for a nice day one weekend to finish the dome and do some cutting on the skins. Just a couple of holes to cut in dome, and a whole load of filing and sanding to make things fit properly. I have the hinges now so can start glueing those in and making the flaps work.

Slow progress, but it is at least progress

Slicing my inner dome!

So, finally got some time on a weekend with nice weather to get outside with the inner dome and my Dremel. Whilst the dome set I got had a laser cut outer dome, the inner one was totally uncut. The aluminium domes come as an inner and outer to allow you to have the indent around each of the panels, and also lets you have a nice lip if you have the panels opening, which is something I want. Of course, this means lots of holes to cut. Any panels that are going to open have to be cut out, as well as all the holes for the lights and holo projectors (HP).

IMG_0182To start off with, all the holes were marked using the laser cut outer dome as a template. HP and light holes were to be the same size as the outer ones, but the opening panels need more of a lip. A tip I learnt from reading other builder’s logs was to use a large washer, and to put the marker pen in the center, then roll it around the edge of the opening. This gives you pretty much a perfect size for the lip. Next comes the scary part.

Cutting disc grave yard. They really don't last long, and some of the shattered. The larger ones broke in the center so were unusable.Cutting the dome! These things aren’t exactly cheap, and even worse they’re quite hard to come by, having to wait for runs to be done of them by the guys in the states. But, its got to be done so I got the Dremel and a whole bunch of fibreglass reinforced cutting discs for it. I needed a lot as the wear down extremely quickly. I went through over two dozen of them just on the dome. Thankfully I got plenty.

I found the easiest way to do it neatly was to do the large part of the cutting with the dremel, at least enough to make a cut a few cm long so that I could get the hacksaw into the hole. The hacksaw made a much cleaner cut with more control. The Dremel had a habit of biting in and running off a bit, which made some of the fine cuts a bit difficult. By far the hardest bits to do were the circles for which I ended up making a load of straight cuts through the center to form a star pattern, then gradually cut each of the prongs off. Once I had the main parts cut I attached all the cuts with a large file to take it to the lines I had drawn.

All the pie panels done now, along with the top HP. The metal on the spun domes is a fair bit thicker at the top. Just needs a load of filing and sanding to make smooth and safe.It took a good few hours to get through everything, but it was worth it. The holes are still a little rough and still need some sanding down with wet and dry. Also the circular holes all need to be made a little bigger. They were originally marked up to be the same size as the outer dome holes, but ideally they need to be at least a few mm bigger, especially the HPs. Another tip that I’ve found on the net is using a glass wine bottle to help with the sanding of the circular holes. Wrapping some wet and dry around the neck, you can sand in a circular motion to get an even hole.

Still left to do are the rear PSI holes, in both the inner and outer domes. It is the one outer hole that wasn’t pre-cut, so I need to be extra careful with the outer part. The current run of laser cut domes are a lot nicer, with the inner and outer ones laser cut and all just about ready to just polish and paint. Also, I think I’ve been fairly lucky with this dome, as a lot of people report having to cut the inner dome in half to get the inner and outer to fit together properly.

Finally got round to cutting some holes into R2's dome. He now has lights! :)Once the last PSI holes are cut I’ll be ready to bind the two domes together permanently, which is another scary one way step. I’m making sure I’ve as much done with them separate as possible to avoid damaging the outer dome with a slip of the Dremel. I still couldn’t resist having a test fit of the two domes and inserting some of the lighting. It looks pretty good.

Next main steps once its all bonded is to install the main radar eye which I’m hoping to bolt on to make it removable, and then I have to source a load of hinges which seem to be either very expensive, or hard to find.

All in all, a good weekend of work. I would’ve like to do more but due to losing an hour due to the clocks changing, an early morning call from work, and Mother’s Day, I didn’t have much time on the Sunday to do much. Fingers crossed for nice weather again next week to finish off the Dremel work outside. I might also make a start on the skins too.