OpenRocket 3d print design tip!

So I'm working up some ideas for a high power rocket and aiming to go for my level 1 UKRA certification at some point next year. I'm planning to scratchbuild as much as possible which means it can be tricky to know the exact weights of items you are designing into the rocket.. such as the nosecone which I plan to 3d print.

 I can get a really accurate estimate of what a component is going to weigh by modelling the piece in CAD (I have some code I use in Openscad that generates nosecone geometries based on parameters I feed in) and exporting a .stl file as if I am going to print it.

I then load the stl into the slicer I would use to generate the gcode for my 3d printer "Cura". Rather wonderfully having selected the infill and the material, Cura will give me a weight value of the finished item. I can then jump back into OpenRocket and overide the mass of the component which is then incorporated into the design and adjusts the centre of gravity accordingly. Neat!

Maker sustainability (or future risks to us doing cool stuff)

A few years ago I was asked to run a stall at a maker event attached to a model engineering exhibition in London. It was a fascinating experience as it linked 2 communities, the live steam/machining/model engineers and the 3dprinting/laser cutting/satellite amateurs etc. It proved to me how much value there is in bringing together these communities and how much we have to offer each other.

There are lots of themes that regularly get discussed around  how much knowledge transfer there is between different groups and its good to see some intergenerational projects going on. I wanted to focus on 3 different communities I have interacted with or am part of, the rocketry community, model engineering (as mentioned) and also amateur/HAM radio  I am saddened when I hear of older members of these groups passing away or indeed the membership of local societies becoming so low they close down. I do indeed mourn the loss of skills and knowledge but I am becoming increasingly aware that we (the maker community) are at risk of losing other stuff, namely structures and accreditation that enable us to do cool stuff.

So.. to provide an example for each group starting with my current favourite subject.. Rockets.

 I want to up my game in 2017 and get into higher power rocket launches and I have plans to try and get my level one certification and also my RSO (Range Safety Officer) exam. Currently the UKRA (UK rocketry association) administer this certification scheme which involve the candidate flying a high power model at a UKRA affiliated club with someone of a higher UKRA certification in attendance and administering the tests etc. Now if had done my certificate some years ago I could have found UKRA affiliate clubs in the Wirral (around 1hrs drive) or around Manchester (1.5-2.5hours). However these clubs have now stopped and my options are Gwent (4-5hrs) Surrey (5-6) or Birmingham (3 hrs). Now this is fine but it shows how vulnerable the certification scheme may be in a few years time... I guess to the point where ultimately this could disappear and the system for people to develop beyond small hobby rockets may not exist.

In model engineering/Live steam similar systems exist (I'm not massively involved in this scene but am aware) for example boiler testing, so if someone builds a model steam engine and wants to run the engine on a club track or on a public running day they need the boiler (a heated high pressure steam filled box!) to be tested and certified as the potential danger if a boiler failed under pressure is probably not dissimilar to a hand grenade! Again this certification system relies on clubs and members of clubs being certified and becoming accredited assessors. (Here is a list of assessors if of use!)

Finally HAM/amateur radio has similar issues in that the exam and certificate systems (although held centrally by the Radio Society of Great Britain RSGB) the actual people providing instruction and hosting and marking and submitting the examinations are clubs and club members. HAM radio does seem to be gaining a lot of support in the maker scene but still some clubs (particularly outside the larger cities) are struggling with an older and perhaps dwindling membership.

So how do we solve this? Well, I'm not sure I have all (or even any) of the answers but part of it is certainly supporting and getting involved in local clubs and if possible becoming involved to the point of being able to assess and accredit others is vital. But also if you are setting up a makerspace/hackspace/techgroup whatever, make sure you spend a bit of time thinking about how you can be sustainable not just in terms of cash flow and membership and knowledge but also certification and accreditation your members might need.

I also wonder if there are more practical stuff to be done? How about the larger maker events (faires, makefests, big hackathons) build in some accreditation events.. this seems an easy win for perhaps the amateur radio foundation license.. (may be more tricky for rocketry certs!)

As for me... I'm off to fill in my UKRA application form and pay my subs for next year.. :)

Finally! Maiden flight!

So.. this project has taken me far too long to realise! I finally got out for a maiden flight on this 450mm quadcopter I've built. It's probably about a year since I bought the bits! Many many many people have built and flown quads these days so it doesn't warrant a massive post but for what it's worth my (budget) recipe for this quad is;

800kv brushless motors

cheap simonk 30amp ESCs
1045 props
CC3D flight controller
FST6 tx/rx
2200 mah 3s lipo

Its gone together pretty well and I am massively pleased with how stable and easy to fly (I'm a stabilised pilot so it feels similar to the couple of small brushed quads I've learnt on... JUST A HEAP MORE POWERFUL!). It was easy to setup the CC3D flight computer using the brilliant free and opensource LibrePilot which gets even more praise for being available for ubuntu.

Theres a few jobs to do and some tidying required but really chuffed to have flown this today and
there's definitely lifting power and space on this airframe for some cameras so hopefully I'll get some nice footage.

3d printing 3d printer bits (and circular economy)

So a friend got in touch this week with a problem.. he needed a bit printing for his 3d printer that had broke. I was very pleased to print him a replacement part. I love that 3d printers can replicate parts for themselves and other machines, as my friends machine is open source they actually sent me a file someone had designed that was an improved version of the part that broke. Brilliant. I hope, whatever the wibbly wobbly future of tech and community brings, that these aspects remain.... a great example of a circular economy.

In fact... we can go further.. 

My friends printer sits in an office in a company (the team in the office all chipped in to have a 3dprinter in the dept to play with!) and when I dropped of the replacement part they said one of the work uses for it was printing replacement gears for a part of the conveying system in the warehouse of the company.. a part no longer available for purchase. So my bit fixes his printer which fixes a conveyor system ... and as I was passing their location with another work task the carbon footprint miles of this part are reduced even further. 

And finally the part that broke is PLA so my friend can stick that part in his compost bin and it will decompose....

reuse, repair, reduce, recycle.

Rocket Ruler now on Thingiverse

Just in case anyone wanted one, I've put the Lasercut Rocketry Ruler design I put together for the recent rocket design workshop I ran onto thingiverse. The ruler is angled so that however it is placed on a tube/cylinder you will always be able to mark/measure a straight line parrallel to the centre line of the tub... very useful for all kinds of things but certainly for marking rocket fin placements! If you are wondering what the symbols at the ends are they represent the centre of pressure and centre of gravity the first of which must be behind the other to make a stable rocket.  Feel free to tip me millions on thingiverse! :)

JETO... Just Enough To Operate, Learning and projects and play

I had a long conversation with the mighty N-O-D-E.net last night that started off as a discussion around homebrew CNC controllers but ended up being a fascinating talk about learning and approaches to projects. I talked about an idea I have used for a long time and it made me think maybe I should blog about it.

So years ago ardent followers may recall I was playing with rolling my own linux live CD's/Images using OpenSuse and Susestudio. It was good fun bundling stuff up and deploying it in a virtual machine before compiling an image you could burn to disc or make a bootable USB drive etc. If I recall correctly it started with numerous presets including an "everything you could ever bundle into the core" down to an intriguingly titled... JEOS... Just Enough Operating System, this option of course had the leanest setup, no windows manager, low GUI, no frills.

This struck a chord with me as it encapsulated my approach to projects somewhat. I tend to learn just what I need to learn at any given time towards a given project during the project. I note things I find interesting but don't necessarily need to know more about at the given time and then tend to explore these when the project they relate to is finished. Therefore learning Just Enough To Operate.

This approach could be considered lazy, an example of "Jack of all trades but master of none", however I don't use this JETO idea to avoid complexity, rather I use it as a governor that stops my mind focussing into learning abstraction that I don't need to realise the thing I am making. Rather like the second and less often quoted part of that phrase;

"Jack of all trades but master of none,  but oftentimes better than a master of one."

I've also used this in some facilitation work, creating activities which allow participants to consider and strip away what resources they actually need to realise a project can be very powerful. It always reduces barriers and increases peoples permission to approach complex projects.

So for me, my JETO concept is really useful combined with my ideas around Purposeless Play (another blogpost at some point) it gets me through most projects.

Rocketry workshop at North Wales Tech 20th Oct 2016

Little plug for this upcoming workshop in North Wales.. there's only a few places left! I'll be bringing lots of model rockets, doing a basic rocket anatomy 101, an introduction to openrocket where people can have time to play at designing a rocket and simulating it's flight etc. We'll finish the night looking at tools and approaches to scratchbuilding rockets from lo tech solutions to 3d printing, laser cutting and CNC routing.

Snag one of the few remaining places here!

Speaking at Glitch Festival of Creative Disobedience

So I am speaking at this festival! "How I Accidentally Ended Up in a Space Race" is my title. I'm really looking forward to it particularly as the term "GLITCH" has made me think about the connections between where I started with things like circuit bending and glitch music and how they formed the following adventures that have led me to having CNC robots and making space parts! If you fancy coming along it's free and I am on at 2pm on the 16th October in the Mostyn gallery.. but do check out the entire festival.. PDF program here

ps it has the mighty Paul Granjon too :)

Databending

Been ages since I did some databending .... in fact I can't remember or find evidence of a period where I did a lot of it! I thought I'd blogged many moons back but apparently not (although my orange banner image across the top of this blog (which needs replacing!) is a databent image from that period! I needed to have some examples of databent images for an upcoming talk I'm doing and here are today's results.. I like them.. (would love to do some big prints and show them..) I made myself databend only images that were photo's I'd taken of things that I have made... enjoy!

Long Live Marbleism!

MarbleRUnSAtOgwENFest from concretedog on Vimeo

Had a great busy weekend with lots of things where I live as the Ogwen River festival (arts/music/poetry ++) was on. One thing we really enjoyed was hanging out in the rain with friends making marble runs from a supplied collection of scrap stuff. This marbling is part of an ongoing exploration of play and flow and marbleism (manifesto here) curated by the brilliant combo of Lisa Hudson and Lindsey Colbourne with which we have interacted with before at pontio and hope to do so again soon!

It's a really engaging activity for both young and old, in this era where everyone seems to bang on about 'STEM and STEAM' with no real passion... it is events like this that seem to me to be perfect.. a combination of arts and technology and making, intergenerational, learning through failure (marbles flying off all over the place), doing stuff, teamwork and as it's stuck in a woodland in the rain it's healthy.. outside, fresh air, exercise, climbing over stuff.. lifting bits, teamwork.... perfect.. long live marbleism I say.

Making Rulers.. and rocketry tools!

Yes.. I've been making rulers! It started because I wanted to make a tool to give away as a freebie at an upcoming Rocket Design Workshop I'm running for North Wales Tech group. One of the challenges when building small rockets is marking straight parallel lines onto the body tubes to mark fin positions or other attachments. A solution is to use a piece of angled bar as it will always lie accurately along a tube and cannot be off square. So for the workshop I thought it might be nice to knock up a small laser cut keepsake one complete with ruler markings and we'll put the workshop date and logos on etc. The two circle symbols on this one are used in rocketry to represent the centre of pressure and the centre of gravity which we'll be discussing in the workshop too so they act as a nice reminder. I cut these on the laser cutter at my nearby newly established Pontio fablab, which is excellent and its so easy to get good quick results on a laser cutter. However I can only access the space every now and again and wanted to see if I could make some rulers without a laser cutter on my cnc router. It's trickier.. the 2 small key chain rulers here are made on 3mm ply and have been engraved with a fine V bit, they are ok, but its difficult to get the resolution and clean cuts at this scale... I obviously need a laser cutter at home... feel free to send me one if you have one spare! Finally someone asked if I drew all the lines of the ruler sections by hand... there is a brilliant path effect in the mighty inkscape which allows you to create a scale along any shaped path.. brilliant!

I'm accidentally in a SPACERACE (and need your support)

Today I sent another pocketqube satellite chassis I made for Paul over to Germany, I've sent them before but this one was special, it's hopefully a flight model.

So regular readers will know that I am involved with building this for a pocketqube satellite project that's main payload is an experimental propulsion system called an EMdrive. EM drives have been discussed for a long time and have created a lot of arguments about whether they work and/or whether they break the laws of physics.. neither of these debates am I qualified or clever enough to comment on! However recently NASA eagleworks paper on their experiments with EM drives passed peer review and suddenly EM drives are less contentious and are garnering much interest academically.

Shortly after the NASA eagleworks peer review story, Cannae inc began to talk about how they are planning a cubesat launch to test their experimental EM drive system. Now.. I do wish them luck and every success... but part of me hopes that Paul and our EMdrive satellite can get there first! Part of this is ego obviously, but another part of me believes that amateurs/DIYers..MAKERS like us deserve to hold the bit of history of placing the first EM drive experiment on orbit.

The trials and tribulations of amateurs/diyers/tinkerers/mavericks is infused in the origins of EM technology all the way back to Roger Shawyer the innovative British scientist who proposed them. So.. how can you help.. well, put simply, we need funds. For testing and validation and launch we will need to raise around 25k euro.. peanuts to most space agencies but quite a lot to us. Although funding space projects is always high risk (no greater a week to know this after the spaceX rocket RUD) and there are many ways to fail you should be reassured that Paul has experience building, intergrating and launching satellites with his previous pocketqube satellite launch WREN. You can also check out our extensive blogs on this project on Hackaday.io

If you can and want to be part of something that possibly could be a watershed moment for mankind and space propulsion please join the brilliant people who have chucked some money in the fund here.

https://www.gofundme.com/25tmmes

And if you can't.. help spread the word about our project in the spirit of making, pioneering and adventure :)

Test flights! Rockets and DIY altimeter hardware.

So got a bit of time to launch this rocket. I built it ages ago (it's an Estes Star Stryker kit albeit with an adapted 3dprinted nose) as I wanted to build the smallest payload carrying model rocket and indeed build a diy altimeter to go in it. 

So the launch and recovery went really well, low wind and clear skies I fired it with a B6-4 motor as I quite wanted to get it back! It launched straight and stable, deployed the chute well and was easily recovered (avoided trees).. perfect.

The DIY altimeter (think I'm calling it SIMPalt) seems fine after a reasonable quick decent (I think the 13 gram weight is at the limit of what the star stryker is probably designed to cope with payload wise).  I was primarily interested in whether the SIMPalt hardware would hold together structurally rather than the data as the code for the altimeter is primitive (library based and not calibrated) and at some point will be replaced with some code a much more talented buddy is working on for me. 

However.. just for fun I pulled the data from the SD card and made a quick curve.. this should not be taken as accurate (can't remember how fast this code was managing SD writes on the logic analyser etc...) but I am quite pleased that despite the noise the shape of the curve is pretty representative of the flight, the apogee to chute deploy and then the change in gradient as it's descent is slowed by the chute particularly. 

Variable voltage DC power supply

Finished making a little case (well a front and a back!) for this variable power supply that I had worked out and wired up a while back and then had on the (enormous) to do pile! I finally got round to drawing a bit of cad and I cnc routed these panels. The panels are just 4mm mdf with a bit of spraypaint to finish them. The gubbins comprises of a very cheap variable voltage dc-dc board which is a lm2596. They come with a small ceramic pot on the board to vary the voltage but I've replaced that eventually with a 10 turn pot to give me the resolution I need to set the voltage to 2 decimal places! (I say eventually, in testing I used an ordinary pot which proved the concept but was difficult to even hit a value to the nearest volt!!)

 These variable buck dc-dc boards take a voltage input of anything between 4v and 35v and will output a voltage range between 1.23-30v, they seem pretty stable. The display is a 3 digit voltage display like THIS, It is important you get one that is listed as having 3 wires, namely then it takes its power supply from the input voltage and has a third wire connected to measure the output voltage.. there are some that only have 2 wires that just connect across the output voltage which means when the voltage drops below around 3.3v.... they turn off! The 3 wire ones happy measure down to the minimum values. (note neither of the links are traders I've used.. rather just to show the stuff!)

The back panel has the inputs on the right and the outputs on the left all on 4mm banana jacks... I love cnc routing.. it makes you able to get these things really precise.. If I had had to drill those holes manually I would have designed it with more space between them making the entire thing bigger!

Anyway.... nice to finish one thing off the pile!

A trip to CERN, Science, Innovation and Open Source.

So.. Been on holiday and toured around Europe taking in 9 countries and doing about 2600 miles over 3 weeks.. lovely! One highlight that is geeky enough to warrant a blogpost is I got a quick trip in to CERN just north of Geneva. As I had the kids with me the 4 hour tour was out of the question but the 2 visitors centres (mikrocosmos and the Innovation Sphere) where definitely do able... and they were brilliant. One of my best parts was chatting to an amazing guide ( a particle physicist who did shifts in the visitors centre and was FULL of passion) and in particular we talked about CERN and open source, prompted by me mentioning using Kicad which CERN have used and developed and shared back into the community, he spoke at length about numerous complex high end software/systems that CERN has done this with and affirmed in me that across the vast majority of the huge complex that is CERN and LHC and ALICE and  ATLAS and CMS an open source attitude prevailed. It was reaffirmed later in the trip wen you stand in front of a console that shows in realtime the data flow mapped over the world that is CONSTANTLY being streamed to hundreds of recipients around the world. Inspiring... I used to alway say that the ISS is mankinds greatest technological achievement... but darn... CERN is a close call...

Here are many pictures!....

Cloud chamber (refrigerated alcohol vapours) that captured and rendered visible particles passing through it.. cosmis radiation and muons etc! Kids loved this!

As well as great renderred and interactive diplay activities lots of real time data was on screen from the LHC.

All cryo pumps green!

Great virtual tour where you could steer yourself flowing through the particle accelerator and the 3 main experiments en route.. Photo's don't do it justice!

More live data

Live power use... blimey!

Outside there was a selection of pieces of kit... such amazing engineering and machining in these, beautiful. The above was a big RF chamber

The Gargamelle bubble chamber... revealed to humanity some neutrino secrets.

An amazing piston... about 2 meters in diameter it apparently pumped ovder 300million timnes in its active service at a rate of 3 revs per minute... each stroke delivering 350 tonnes of pressure! 

Ignore the dodgy dude in shorts (me) this sculpture had cast into it details of all major scientific and in particular physics milestones... inspiring.

The science and innovation sphere runs an immersive mapped projection show on multiple screens and surfaces in various languages... it was awesome and the kids really enjoyed the space. 

My daughter was really engrossed in this sphere... love this picture... the seeds of technology.

Super Cheap Digital Read Out (DRO)

So, a DRO for machine tools (lathes, milling machines etc) is a digital read out that tells you the position of or how far a given axis has travelled. Obviously this useful if you want to make a part or a cut into a component to an accurate size, the trouble is... they can be very expensive! Even a hobby level DRO setup for say a milling machine can run to hundreds of pounds.  One common workaround (apart from using the engraved hand wheels) is to use a Dial Indicator set up to indicate how far a given axis has moved and indeed I've used that technique a lot. (it's a nice technique as it automatically cancels any error due to backlash as it isn't linked to the lead screw and always tells you the exact position of the axis). Still dial indicators and requisite holders/clamps can cost a few quid and can be awkward to get into a good position etc... so when I saw this hack to convert a tyre tread gauge into a micro DRO... I knew it was for me..

So these digital tyre tread indicators are super cheap... I paid £3.99 for one and could have spent less if I was prepared to wait for one to be delivered from the far east. They are essentially a short travel version of the cheap digital callipers that are widely available ( and indeed have the output slot that people have exploited to create data logging calliper )..  So the modification consists of a couple of different things... firstly you need to reduce the drag on the calliper slider which is created by a small steel slip inside the device.. this is for when you measure a tyre tread you can position the indicator then remove it from the tyre to read the result and the slight friction on the slider keeps it in position. For the DRO hack we need it to be as free to move as possible. Once this is removed I turned a small collar for the end of the probe from some Delrin which was drilled to fit the probe end snugly and the other end drilled to house a cheap but powerful 3mm diameter neodymium magnet

For the next part I whipped up a quick drawing to be able to CNC rout a plate for the base that would house the larger magnets. I made the toolpaths tight to the 8mm diameter of the magnet so that they were an interference fit and required pressing in on my small arbour press (also for added security I put a blob of superglue under each magnet). I then glued the magnet base to the base of the unit and hey presto... a portable quick fit DRO!

It works great, I am really pleased with it and will probably for the price make a couple more.. Its also great that the 8mm magnets are enough to hold the device firmly even if only 2 magnets are attached to whatever it's clipped too. The zero function of the device means that even though it only has a small throw (27mm) it is easy to sequentially move the DRO and zero and keep a running count of position over a longer length. 

Another quick make, Ball and socket joints!

In amongst a busy week I managed to fit a little make in! I was inspired to make these by my twitter buddy Rob Ives ... for the uninitiated Rob is a master maker and what he can't engineer out of paper doesn't leave much! Check out his website for some great stuff and projects to download.. https://robives.com/ 

So anyway.. these ball and socket joints are made from some cheap 12mm nylon beads I got on ebay which I drilled and tapped (awkwardly... the nylon tends to melt when drilling making it tricky) to take some M4 bar.. The wooden sockets are cut on my CNC with the holes for the beads being 9mm diameter. A bit of tension on the bolts and the result is a grippy yet positionable joint. I then turned up a small 8mm lug and tapped it to M4 as well and attached a crocodile clip (with a blob of epoxy) to the other end. Hey presto... another accessory for my ever growing accessory station! 

Quick make... baseplate for accessory stand

Stalwart readers of this blog (a very elite club!) may know that I have an ongoing project that started off as some Dial Gauge accessories which then expanded to include a tapping stand and indeed on my last post about making the PocketQube chassis I posted a photo of me using it to tap some small holes. It worked great but made me wish that instead of just a big lump of (recycled in my foundry) aluminium as a base I had something that I could put my precision vice on. So to the scrap pile! Within my hoard I had a base off an old black and decker drill press stand (the type you insert a hand power drill into a collar). Despite being a pretty poor casting that has a few marks from some abusive drilling with a few file strokes the base sat level on a level surface and cleaned up well. A lick of grey enamel paint smartened it up a bit as well.

To attach my DTI/tapping stuff I turned a bit of mild steel to the diameter of the old drill column and then drilled and tapped an M6 hole into it. Into this I inserted a short piece of M6 threaded rod with a bit of thread locker to keep it in. It's worked really well. Next on the list is I need to mill some flats onto the piece that screws onto this base and has the clamp slits that hold the uprights and make a spanner so I can nip it up a bit more. 

The obligatory before pic!