Sunday, 10 January 2016

Knobs and Power!

So a couple of little projects in between everything else this weekend. Firstly a classic hack turning an old ATX power supply into a bench top power supply.. I'm not going to go into too much detail as there are THOUSANDS of instructables and blogposts on how to do this out there.. I had to add a 10 watt 10 ohm resistor dummy load across the 5v rail to make all the outputs create the correct voltages. Of course I used the CNC to make a little breakout panel which was interesting in terms of I realised I am at the point where it is quicker and more accurate for me to whip up a quick drawing in inkscape and rout it rather than breaking out a drill and saw!

Second up links to my previous post .. all the universal clamps on my stand system are closed by 4mm threaded systems usually a bolt with a handled nut like so.. I hadn't made any more of these and currently am sharing the couple I'd made between different bits of the system. These are great but equally take a bit of time to make as they require quite a few operations. The handle parts are press fit into a 4mm reamed hole as well as the tapping etc..and they also use up my meagre supplies of nice EN1A steel! So I whipped up some nice knobs from some 6mm MDF with a routed hexagonal hole into which I could press fit a M4 nut with a blob of super glue, they work really well.

Tuesday, 5 January 2016

Projects within Projects!

Got some time in on some projects of late and today I finished making a small project.. that I needed to make as part of another ongoing project! The overlying project requires some tapping of M2 threads through some 10mm aluminium bars and I am keen to make the threads as accurate as possible as I want to make sure as much of the thread is engaged as possible when the bolts are fitted. I am reasonably good at hand tapping and also use the tap in a pillar drill or tap in the tailstock technique but for really small taps I find that you lose a  lot of feel this way which can result in broken taps or malformed threads. So I needed some form of sensitive tapping stand that allows you to keep the sensitive feel whilst guaranteeing the vertical introduction of the tap to the workpiece. As this is only for small work I decided to make an arm and chuck shaft that would fit onto my existing (and ever growing) clamp stand system that started out based on Harold Halls Dial test indicator stand. So the chuck shaft is held in the bush and arm vertically whilst still being able to be turned and lowered and raised through the reamed brass bush. I made a bit of an error on the hole to attach the assembly to the main upright and made the hole slightly oversize (dodgy sharpened drillbit!) Although the clamp would clamp it only just held so I added 2 grub screws which hold it firmly. It's actually quite good that way as I can roughly set the clamp height quickly and then secure it afterwards.
The chuck shaft is formed from a bit of mild steel and a cheap small drill chuck from ebay. I turned the shaft of the threaded keyless chuck into a taper and made an undersize taper bore into the steel shaft, then a careful few pressings on the arbour press and it is well attached and straight. I just need to make a handle section to apply the required turning..I'm considering whether to make a press fit knob for the shaft or whether to machine some flats into it allowing tapping handles to engage it. 
Of course the thing about all the accessories being compatible is this can be used in conjunction with other items! It also occurred to me the chuck shaft could be clamped in one of my universal clamp assemblies and used as a pin vice. 

Wednesday, 30 December 2015

Keep It Simple (Stupid) DIY Rocket Altimeter SD Datalogger project

Been working on this little project, a while back I prototyped a diy altimeter using an arduino pro mini (8mhz 3.3v) and a BMP180 barometric pressure and temperature sensor. I have now replicated the working breadboard prototype and made this tiny point to point/deadbug style version. 

The reason I have aimed to build it as small as possible is that I wanted the altimeter to fit inside the payload section of this small "Star Stryker" Estes Rocket kit I built a while back. This rocket payload section probably represents the smallest payload capable rocket on the market so the design will therefore theoretically fit into any payload section.

Weight wise it is 6.5g without the battery and currently 13.7g with a battery.. however the 200ma lipo could be replaced with something smaller (it was just what I had lying around!)

The device is activated by the switch that means that the payload section must have an access hole/port to enable the switch to be toggled with a tool.. but this is ok as the BMP180 sensor needs the payload section to be vented anyway to equalise the pressure and take an accurate reading. One slight addition I am going to make is to attach a larger LED to the pro mini. This LED will be lit on boot and will remain lit during a delayed setup part of the code (10 seconds or whatever is needed) to allow time for the operator to return to the launch controller. Then, when the LED is off, the main loop of the program is initiated writing data to the sd card at 20hz

The code currently is a bit shabby (I am no great coder!) and is just a mashup of  SD library and a BMP180 library sketches.. it's crude but it works! I'm going to work on the code with a good friend in the new year and when we have it polished (possibly dumping data to a .csv file for quick plotting) I'll opensource the project in case it's useful to others! 

Friday, 11 December 2015

OpenRocket and rocketry CNC workflow...

I've been playing with OpenRocket for a while now, essentially this little free java application allows you to design rockets and simulate their performance with an extensive database of rocket engines built in. It calculates both centre of gravity and centre of pressure and uses the Barrowman equations to calculate the stability (or lack of) in your design and has lots of aerodynamics code built in calculating drag coefficients etc. Being able to simulate launches and recovery is excellent and allows you to both optimise your design in terms of feasible altitude but also can allow you to fly within the limits of a particular altitude ceiling. Simulation also is important when you get up to qualifying certification flights for high power rocketry as your rocket needs to perform similarly in real life to what you have submitted in simulation data.

So all of this was exciting as I start to design my first scratch built rocket attempt, however an added excellent bonus is that Openrocket exports it's simulation data into a PDF document which I hadn't done until recently as I wanted to printout some data. The export function also will print out various other useful items from your design including fin templates and centring rings (rings that hold the inner engine tubes to the outer airframe tube) as PDF is a vector format it is readily accepted into most CAD/CAM environments and therefore it is a trivial matter to create tool paths to cut fins and rings etc on my CNC router. Slick!

Monday, 30 November 2015

Soundlab, heart and soul at NESTA HQ

With the echoes of Electric Fire's "Do your own thing" still earworming away I sit reflecting on a great event I was lucky to be part of last week at Nesta HQ in London. Soundlab, as part of Heart and Soul, has been exploring in partnership with music tech companies, NESTA and Goldsmiths uni how music technology can be more accessible and how barriers to expression can be reduced.

I am linked into this via the mightly Ashley Elsdon from Palmsounds, Ash worked tirelessly on this event getting companies and developers to give their time (and app codes!) to attend these events and display their tech.

So many great things stand out about this event, the first section of the day was for NESTA staff and from chatting to them they seemed to be really excited to see the reality of a project that they fund and work on. Director of NESTA's Digital arts and media Tim Plyming summed it up astonishingly well when he described not having got on well  with music education and feeling excluded from it..yet within the first 10 minutes of the first Soundlab event he attended he  created more music than he had in his life previously.

I could write pages about the thoughts that these events bring to the surface around accessible innovation, creative process, gestural and physical performance interfaces etc, but rather I will cut to my overriding memory/thought of this event... It is AMAZING and incredibly uplifting to be part of an event where such joyous noise and music are made so readily. It's mindblowing to see people who possibly would be considered by others as "non verbal" and poor communicators..with the right barriers reduced, be up on stage commanding an audience with deep rich emotional performances... that I still hum days later.... I await  Electric Fire's first EP/album keenly. Huge props to Ash, Justin, Mark and all the Heart and Soul team.

Picture dump.... :)

Sunday, 22 November 2015

A little light prototyping

 Spent a bit of time today making this light prototype out of some MDF I CNC'd and some yellow LEDS (next revision will be white but I bought a 1000 cheap yellow LED's some years back so they get used first!). It was quite a challenge to solder so I'll tweak the CAD to make the pocket a bit larger to give me a bit more room to work in. I have a few ideas for different sizes of these... Firstly the internal diameter of this one matches the spindle currently on the CNC so I hope to have a snazzy spindle light that I'll probably attach with some small neomydium magnets in the back of the case. Another size I'll make for the manual mill spindle and I fancy making one that could fit to my DIY helping hand accessory for use in combination  with a lens. They also could make a nice light to mount on a camera to take macro shots.

Monday, 2 November 2015

Getting into rocketry

rocket launch keychain camera from concretedog on Vimeo.

So I've been getting into model rocketry, I got bought a starter set as a gift some time ago and finally got the 2 rockets built over the summer, I've launched them a couple of times but yesterday was the first time I did some video, both from the ground and also attaching a cheap keychain camera to a rocket. The above is the result. (And yes.. forgot to set the camera date and time so appear to have launched over 150yrs in the future!)

My lad looking very pleased with the larger estes amazon rocket

So... I have plans! I have a larger kit that will step me up to use the highest over the counter rocket motors available and then after that i'm going to look into getting certified to fly high power rockets. I'm looking to diy as much as possible so have been playing with designing rockets in virtualisation using the amazing free design and simulation package OPENROCKET .. I've also got into sewing lightweight ripstop nylon to make parachutes! I'm learning a lot about sewing and am aiming to make some cross form parachutes after reading some chute theory and running some math. I've also built a little prototype jig assemble that has worked well to enable fixing fins at exactly 90degrees from any given centreline of a circular tube.. I'm going to build a better version at some point and post again.