17 April 2015
I managed to get the skin on the hopper last night. 32 individual sections allow the balls to move freely into the cannon, simply rotate the wheel and drop the next stack into the barrel. It's interesting in theory but it's taking way too long to build so the stacks are only half as tall as they should be. 2 of the stacks were warped, I couldn't figure out why so I just cut them out.
16 April 2015
14 April 2015
13 April 2015
08 April 2015
07 April 2015
This is a simple voltage regulator kit based upon the LM2574 step-down regulator IC.
If you have every needed to efficiently step-down a voltage from anything up to 60V DC to 5V regulated then this kit is for you. It can supply up to 500mA of current and is a DC-DC switching circuit which efficiently steps-down the voltage.
It is available from just £7 (including delivery within the UK).
We have recently been working with Product Health to develop some hardware for monitoring battery banks in off-grid systems.
Product Health are working on remote monitoring of systems to ensure they are working and pre-empt any maintenance or repair which might be required.
The product specification was to build a low-cost, reprogrammable and accurate unit to measure current and voltage at a reasonably high sample rate and send that data, when called, via a communications interface.
06 April 2015
I have totally managed to remove the lower half of the machine and the only thing I've lost is the ability to engrave boxes (or at least I have to engrave boxes slightly differently)
Development work on my Catan set continues. This is another complete set done with painted tiles instead of real woods. I'm trying to balance materials costs vs time costs while trying to minimise both but it's not going so well.
- I'm happy with the artwork now but I'm not sure about the painted tiles, it's a bit of a false economy because the amount I save on real woods I lose on painting and drying time.
- This set uses 1 magnet per side which means the tile only match up in 3/6 rotations. This is fine for the resource tiles where the orientation doesn't matter but this causes an issue with the port tiles. I suspect I'll be switching back to border tiles for the next test.
- I tried to bring the tile thickness down, the base is made of 2mm mdf, the same thickness as the magnets but it's hard making sure each magnet is perfectly flat. I'll be going back to 2.7mm poplar for the base.
- The coloured resource section is 1.5mm (making the while tile 3.5mm thick). There is 0.7mm between the tile border (0.8mm ply) height and the tile height, this isn't really tall enough to keep the roads in the right places. I also don't like doing the borders in 2 segments so next time there will be a whole layer of 0.8mm across the top and 1.5mm will be stuck on top of that. So new tile thickness will be 5mm, so substantially thicker but with good reason.
05 April 2015
Finally finished my second pair of Jaywalker socks. These are in the Jubilee colourway of King Cole Zig Zag, which pretty much looks like something the US Army would sell at Captain America shows trying to get women to knit more socks for soldiers.
It is sooooo tacky. I love it. And I know that the yarn’ll last, because I have another pair of Jaywalkers in Zig Zag’s Cornucopia, which is like the 70s exploded in a pair of socks. But so comfy and so durable. So I’m hoping these are too.
04 April 2015
03 April 2015
02 April 2015
01 April 2015
Firstly and most importantly the software is able to detect the presence of the Z controller. The Z controller is an arduino nano, this means it has a USB to serial chip on it and it can be plugged and unplugged at any point. The PC controller detects removal and arrival of USB devices and uses those notifications to check that the controller is still attached. It gets a list of current serial ports and attempts to open them all one at a time, if successful it pings the device with a "?". If the Z controller is on the other end of the port it replies with "Z Controller" and the PC knows it has found the device. The status is updated in the square at the top which show green/pink for connected/disconnected but it also gives a tool tip text response too.
Because this is really going to be used to drop the z axis by a specified amount between cutting layers (allowing for n passes of a thick sheet of material) I added a text box on the bottom which you can enter a specific value in to. The value is parsed to make sure it is a numeric value, again with pink/green qualifiers. The actual value is sent to the controller when you click the Green +Z and -Z arrows.
So if you want the Z axis to drop 2.5mm change the value in the text box and click the down arrow.
31 March 2015
My most recent project again has gone up over on Just Add Sharks but it's too good not to at least warn you guys about it.
This is a simple, low-cost amplifier kit based upon the LM386 amplifier IC.
It has a maximum output power of 1W, which is good enough for amplifying mp3 players, phones and also the beeps and sounds from microcontroller projects.
This kit has one surface mount component, the LM386, which is good for those learning to solder surface mount components. The rest of the parts are through-hole.
It is available for just £6 (including delivery within the UK).
28 March 2015
Lasercut 5.3 has a bit of a slack way of dealing with the z control, you nudge it up and down a bit until it's in the right place according to the height tool. The amount depends on how long you hold the button for. One of our customers wanted to be a bit more specific about how much the Z axis moves, that way they could make 5 passes on their material and drop the Z axis by 1mm each time. So I made them a custom Z axis controller, this one connects to the PC and allows you to send specific mm commands to the Laser cutter. The PC end is a simple interface that allows you to send 0.1, 1 and 10mm commands to the controller, but it also allows you to send a custom distance. (software bundle here)
The PC controller actually detects when the USB serial port of the Arduino is attached and removed and it opens and closes the serial port appropriately, this means you can leave the program open all the time. The laser cutter, softdog dongle and Z controller could also all be attached to the same USB hub so you only need 1 wire running to the laptop while cutting.
26 March 2015
25 March 2015
24 March 2015
I've been designing a breakout board for the ACS758 hall-effect current sensor. The first few prototype boards came in and I decided to give them a quick test. The results were not quite as I expected so I thought I'd put write about them here, for others that might be using this IC.
These current sensors come in a number of ranges (50A,100A, 150A and 200A, all with uni and bi directional variants). They use the hall-effect, which measures the change in the magnetic field to measure current. This means you do not need to install a shunt resistor, with its associated power loss and voltage drop.
23 March 2015
22 March 2015
After Donkey Kong, Pacman and Lunar Lander we were having a discussion about which other games could be turned in physical versions. So about 6 months ago an idea was forming in my head, more recently I've managed to get all the pieces into the right place to make it happen and my physical version of space invaders was born.
I've document the whole project over on the sharks blog because I've used a Whitetooth laser cutter, a rotary attachment and a break in board.
So you can check out the whole project here
18 March 2015
17 March 2015
I have run a number of solar photovoltaic and off-grid power hands-on workshops and I recently ran another solar PV workshop with EWB Nottingham. This was a two hour workshop run at Nottingham hackspace.
Engineers Without Borders UK (EWB-UK) is a student run organisation trying to connect engineers with the field of international development. They do this through placements, training and outreach programs.
15 March 2015
While building my model SpeedTwin ST2 I needed to neatly cut some foam. Since I had a bunch of 6mm laser safe ply available and needed to cut some other bits the next day I decided to design my own hot wire cutter and cut the parts out at the same time.
The cutter is designed to be built around some 1/2inch spruce engine bearer stock that I had lying around. Any roughly 1/2inch square section wood will work so long as it is stiff enough.
Most of the parts are designed to be built from 6mm ply, with a few 3mm bits. 6mm, 3mm and 2mm bolts are used to attach the fittings to the wood. Some nichrome wire is used as the heating element, with some stiff wire on the other side to tension the cutting wire. I added some springs to help maintain the tension as the wire stretches. These would work better on the other side to that shown in the photos to increase the amount of wire available for cutting.
I’ve found lots of articles online about DIY hot wire cutters that suggest using a transformer connected directly to mains, with no current limiting or anything. DO NOT DO THIS. Those people are idiots (and they’re most likely in a country with a lower mains voltage). I’ve been running my hot wire from a lab power supply in current limited mode and it works nicely and gives excellent control over the temperature of the wire.
I’ve uploaded the DraftSight files to my GitHub account for anyone who is interested in them, but please bear in mind the finished product could be dangerous and I take no responsibility for what you do with it.
Foobot is a project I started around November 2014. It’s still a work in progress, but the time when I should have written it up is more than due.
Foobot is robot table football game, with two teams of two tiny adorable robots. The robots are controlled by classic Nintendo and Sega controllers, hopefully it can can finally settle the age old console wars.
The intention eventually is to build some games around these robots. Possibly with the ability for a computer to control some of the robots via some image processing if I’m feeling really ambitious.
The robots are built around an ATtiny2313 microcontroller, with an SN754410 to control the motors and a cheap 1402 433mhz radio receiver module. This is mounted on a simple laser cut perspex frame with two wheels mounted directly onto the motors.
The initial design was built on stripboard, but once I had it working I ordered a professionally made PCB via http://dirtypcbs.com/. This was the first PCB I’ve had made and the quality turned out to be better than expected for the price and the 3 week shipping was pretty bearable.
As the radio modules are very simple (and one way) I decided to avoid the problem of collisions between multiple transmitters by attaching the controllers for all players to a single radio transmitter. The transmitter reads all of the controllers and then sends a packet addressed to each robot in turn. Messages for the robots consist of a robot ID, the message payload and a checksum. Robots ignore all messages not addressed to them and any messages with invalid checksums. Dropped packets or interference are dealt with by hoping the next message with more up to date data will arrive.
The transmitter module is based around a tiny 8 pin ATtiny13 microcontroller. This has just enough pins to read data from all of the controllers and to send a signal to the transmitter module. Some of the lines are shared with the In-Circuit Programming interface for the microcontroller – these were chosen to be the outputs so there was no need to worry about other hardware interfering with programming.
In order to read 4 controllers with 4 pins the transmitter uses a pair of controller interface boards. These have a socket for a NES controller (which contains a shift register so the button states can be read out serially) and a 74LS165 shift register which enables the Master System controller to behave like a NES controller (it is just 6 buttons with a shared common pin). The 75LS165′s latch line is inverted so a transistor was required to invert this in order for the same latch signal to operate both devices.
With this setup the only extra pins required on the microcontroller are shared latch and clock signals and a data line for each NES/Master System controller pair. The serial output from the NES shift register is passed into the serial input on the 74LS165 so sending a latch and 15 pulses reads 8 buttons (2 unused) from the Master System controller and then 8 buttons from the NES controller. The Master System buttons are mapped so they come out in the same order as the buttons with equivalent functions on the NES controller (A, B, Select, Start, Up, Down, Left, Right and 2, 1, N/A, N/A, Up, Down, Left, Right).
In the case of the transmitter the circuit was initially tested on a breadboard. This proved quite fragile due to the flying leads to the various controllers so I ordered some more custom boards. The price break on DirtyPCBs is at 5x5cm, so I designed a single board containing the controller interface and a board to carry the microcontroller in a single 5×5 square. I designed tabs into the board outline to allow the two boards to be broken apart. When fully assembled the transmitter contains two of the controller interface board and one of the microcontroller board, so there will be some spares of the smaller board. The cheapest quantity from DirtyPCB is a protopack of 9-12 boards (I got 11 both times), but I only need one transmitter currently so that works out just fine.
I struggled to motors that are both cheap and small without a ridiculously high RPM. The motors I settled on in the end run at around 16000 RPM and 9 volts. Because of this I had to add some code to pulse width modulate the enable pin on the motor controller. Turning requires very little force so it runs with a very low duty cycle. When moving forward initially the motors run at full power to get the robot moving, after a short delay the duty cycle is lowered to avoid accelerating too fast.
Tuning the PWM settings has proven fiddly, and testing with the programmer attached is almost useless as the wires affect the motion of the robot too much. Because of this I implemented an over the air update of the PWM settings. This added some extra commands to update the PWM duty cycles over the radio, and a command to write the to the microcontroller’s EEPROM to save them permanently once the behaviour feels right.
I’ve uploaded the project to github, including all of the code, schematics, PCB layouts and chassis/case CAD files. Feel free to use these, but please bear in mind that the project is still a work in progress.
Finally, here’s a video of some Foobots in action (before the over the air PWM tuning feature went in):
Just a quick post, it's been a busy week I've been out delivering lasers to people for Just Add Sharks (more to deliver next week too). I also have a great monthly project I've been working on which is very nearly finished so please accept these simple meeples for the week :)
09 March 2015
Over the past two years a number of people have been working on a series of books for Engineers Without Borders placement volunteers.
These books are designed to cover the basics of the theoretical, practical and social aspects of doing engineering projects for devlopment. They are meant as a basic guide, a collection of case studies and links to further information.
I have helped co-athour the Energy book and it has been published and released as a free .pdf.
I'm very proud of the final result which, I think, is an amazing resource.
07 March 2015
Last design from this batch, this dual dragon pattern also looks great, incredibly intricate details but the laser just copes with like any other cut.
Some of the pheonix cut previously have made it onto shields and have been coloured and latexed. Those things look fantastic, there is so much potential for lasers in LRP weapons, a line of matching group shields like this would look amazing on the battlefield.
06 March 2015
05 March 2015
Terry from Occasions Boxed contacted us at Just Add Sharks asking if we could do a sample to demonstrate the capabilities of the Laser cutter. He sent me a well coloured raster image which left me scratching my head a bit. I little bit of creativity later and I came up with the above, he obviously liked it because he purchased a Blacknose over the weekend and I delivered and installed it on Monday
02 March 2015
Looks like I totally forgot to add the cutting video to the bottom of yesterdays post. It cut a bit too slowly and burnt through the wood rather than marking the surface, it also seems to be cutting sections twice (which I just noticed)
28 February 2015
As already mentioned I used the Lasermode Variant of GRBL, this is freely available and can be easily compiled and flashed to the device using the Arduino IDE. The only minor problem was that I had to use the most recent development branch of the IDE (1.5.8), but that has now gone into stable release (1.6.0).
GRBL is very clever, all of the machine specific settings are stored in EEPROM on the microcontroller. This means if you update the software all the settings remain on the device. All the EEPROM settings are adjustable using text commands over the serial port. Since the software is downloaded using the Arduino IDE it was easy to set up the device using its serial monitor.
The first task is to work out how many steps per mm the laser has. Read the settings to figure out how many steps per mm are currently being used, request the axis to move 10mm and measure how many mm the laser actually moved. When you know how many steps it took and how far it went you can calculate how many steps per mm the machine actually has. The Blacknose has 78 steps/mm on the X axis and 156 steps/mm on the Y axis.
The next task was to set the appropriate direction bits, GRBL has a setting to make sure the direction lines appropriately, the defaults are acceptable. Finally you test the homing cycle to make sure both axis run up to the limit switches and then stop. The image will appear rotated by 180 degrees because GRBL has the origin in the bottom left and the blacknose has it in the top right. It is possible to modify the GRBL settings to correct this but it hardly seemed worthwhile.
GRBL accepts G-Code sent to it via the serial port, so you need 2 additional pieces of software, one to create gcode from your drawings and one to send lines of gcode to the machine. There are numerous way to create G-Code but the one that sprung to mind was DXF2GCode. Most vector programs can output dxf so this solution is independent of drawing package.
It's a very simple offering, the file is loaded and displayed in the main window along with the origin point. You are able to turn each of the entities (drawing lines) on and off as required and you can set the feed speed for the drawing. Because it is intended for all CNC machines it includes options for z axis height but we can just set all of those values to zero. The file created contains a series of G-Code instructions that describe the imported image.
To send the G-Code to the arduino I chose to use Grbl Controller, again it's a cross platform solution and it comes with a few useful Jog functions to move the laser head around which makes it good for testing the machine. A handy text box allows you to type commands directly to the controller. You select the required G-Code file and it is sent line for line to the laser cutter. The laser cutter executes each instruction and cuts your required shape.
Results and Conclusions:
GRBL works on the machine, I was able to cut out the test pattern with only minimal editing of the G-Code. I was a bit worried about the response times, There seems to be a noticable delay between turning the laser on and moving the head. With a CNC mill or a low power laser diode this probably isn't noticeable (or may even be necessary to get the mill up to speed), but with a 40W laser this leads to a burn mark on the work piece.
The is no reduction of power as the laser goes round the corner, This is due to the G-Code being fed into the machine but ultimately it means the corners cut better/burn more than the straight lines when the laser head is moving at speed.
It's an extremely functional arrangement that was pretty simple to set up and get running, There was a bit too much manual tweaking to get it running with the big laser so it's probably best suited for small laser diodes. It's all a great learning exercise, next stop is a serious reduction to the amount of metal work on my laser cutter, before moving over to a Laseraur type controller (whatever that entails)
27 February 2015
26 February 2015
I shy away from Birch plywood, it's more dense than the poplar I love so it's useful for more structural things but it cuts slower so I tend to build strength into my designs. Kevin from Kitronik was telling me about their new supplier and how nice the new material was. So I bought some 0.8mm, 1.5mm, 2mm, 3mm and 6mm and I'm extremely impressed with all of it.
The last batch of birch I bought was fairly rough on the surface but it also had a fair number of voids and knots in it. Every time the laser hits one of these it doesn't cut cleanly and you have one of two choices, you can spend just as long freeing the thing up by hand afterwards or you can turn the power up and re cut it. Kitronik has really grasped the idea that quality is essential for laser cutting, I would happily pay a little bit more for quality wood that cuts first time because it's going to cost far more if I have to do it a second time. The best part of it all is that the high quality wood from Kitronik costs the same as the other stuff so there is no contest.
The second thing I've noted is how much nicer the 1.5mm ply is. On previous models I've had a really burnt and black edge and I've had to cut it slower than the 6mm stuff to make sure it cuts cleanly. I'm convinced this is because it was actually non laserable external ply, the Kitronik stuff really is laserable and uses internal glue between the layers so it cuts cleanly.
It's another rave review for Kitronik but with good reason. Get some birch (and Poplar (and Perspex (and Polypropylene))) for yourself, you'll be glad you did.
25 February 2015
24 February 2015
An open challenge has been set for the UK Maker Faire this year. Titled the Mega Fun UK Lasercut Challenge (@MFUKLC) the goal is to fire as many ping pong balls as possible at a target in a 30 second time frame.
Well the challenge has been set and busy or not there is no real way we can ignore it so I've had to get my thinking cap on. The competition states that we're only allowed to use an A0 sheet of material which means optimising all the parts to use the smallest amount of material possible. This is a first attempt at a ball hopper, my current launcher design has a lot of capacity but relies on a steady feed of balls so the hopper must hold as many balls as possible and allow them all out in an orderly fashion. This design is easily extendible to include as many rows/columns as required (svg here)
21 February 2015
I often get asked to answer questions for articles I never get to see or fill in surveys for research Continue reading
19 February 2015
It's very easy to forget how long it takes to go from prototype to product. Absorbing an awful lot of my time this week is a remake of my Settlers of Catan set. It's more than just a remake though, since I've used that set a fair bit now and there are things I wanted to change and improve upon. The photos above are 4 variations of the tiles, each one improves something different but they all take time. Set number 4 (bottom right) is the one that's ready to move forward but it's only a variant of the final set so there is yet more dev work to do.
Expect more on this in the near future.
12 February 2015
Mum and dad were always very generous to me, particularly when it came to toys that allowed me to explore my obsession with experimentation and construction. As quite young child I had got the “starter” Philips X20 electronics kit, which I played with a lot. Not too long afterwards, sometime in the late 1970s, and still as a pre-teen, I got the monster Philips Radionics X40 kit for my birthday.
For a child excited by technology (in a hands-on way, not the XBOX, iPad, App-store version of technology that many kids love today) the X40 was an impressive and exciting toy. It allowed you to build 40 projects – called “Experiments” in the manual – from testing to see whether water was conductive (boring) to regenerative radio receivers. The radios were the things I loved the best, particularly when dad and I had made special coils and we could tune it to get SW broadcasts. In the pre-Internet era hearing Voice of America and Radio Tirana was exciting.
As well as the radios the kit had some simple digital electronics. I learnt the function of all the basic logic gates from the X40. I also particularly remember a project which was a multivibrator driving a frequency divider. That project used all four transistors in the kit and seemed particularly sophisticated.
Dad put a lot of thought in to which system to buy and I think he liked the Radionics kit because it was open to expansion and the construction technique was very much like real electronics. The kit came with a large (A4 sized) PCB which was cleverly designed to work with all the projects. The components were mounted on plastic bases with brass screws that went through holes in the PCB to make the connections. Basically it was a solderless version of through-hole PCB construction and you got to see the real components pretty much unpackaged. When I went on to building projects on breadboard and veroboard it was an easy transition because I was so familiar with what things looked like from the X40.
I can’t claim that all the time I spent with the X40 taught me much about electronics theory. Even now I find the lumps of theory dished out in the manual rather hard to follow. At the time they were way over my head. What I did learn was a lot about practical electronics and also that electronics was an experimental science – you could just try changing stuff and seeing what worked. Also the presentation of the manual with the circuit diagrams and the physical layout side-by-side taught me to read circuit diagrams intuitively and that’s a skill that’s been really useful.
The connection with Philips seems to be a bit tenuous by the way. The X40 and other kits in the same range were rather confusingly co-branded “Philips” and “Radionics”. Philips had their own range of kits that was popular in Europe and as far as I can tell the X40 was a created by the UK Radionic company who I guess then applied the Philips brand under licence.
For the fundamentals of electronics using bipolar transistors I still think that the basic outline and structure of the X40 projects is very appropriate, so much so in fact that when I designed by Electronics for Absolute Beginners course I took the X40 as the initial starting point.
I still have the components and manual for my X40 kit – one day I’ll have to build some circuits to show you. In the meantime, here is a scan of my manual (48MB to it’s big!).
I am not the only fan of the X40 on the web. Try these sites for more info, photos and manual scans:
- http://ee.old.no/library/ (Radionic scans near the bottom)
10 February 2015
08 February 2015
I had previously made a Laser cut Knob for the Blacknose laser cutter but I've been using it a bit recently and there were still a few issues with it so I redesigned it. This knob is 50% longer but that's 12mm on either side. On the top it makes it easier to grip without scraping your knuckles on the laser frame, on the bottom the knob extends beyond the square section to hold the shaft better, this makes it far less likely to slip off while in use. (svg here)
07 February 2015
It’s been a long time since I last posted to this blog, I’ve done a fair bit of brewing in that time but nothing noteworthy. (mainly kits) a few months ago I did another batch of ginger beer with the following recipe:
500g Light DME
Juice of 3 Limes + zest
Juice of 3 Lemons + zest
545g Ginger (Blended and steeped)
1tsp yeast nutrient
1tsp cayenne Pepper
Wilko’s ale yeast
OG: 1.050 sg
FG: 1.010 sg
For this one I tired using cayenne pepper which did add a little fire to the taste, I also upped the ginger which make the drink too strong and it required diluting with lemonade to be drinkable. I also blended the ginger which made it much easier to extract the juices.
I’m currently planning batch which I’ll give a more detailed post for than this. I’m dropping the ginger contents and somewhat going back to basics with batch 6 which should hopefully give something more immediately palatable.
05 February 2015
03 February 2015
Welcome to WordPress. This is your first post. Edit or delete it, then start blogging!
For the longest time I've been quite anti 3D printers. It's a lot of time and effort to end up with a noddy little plastic toy that's badly ribbed along the edges and could often be made easier with alternate tools (like a laser cutter). It's really about using the right tool for the job though and there are things that 3D printers can do better. So I used my Christmas money to buy myself a 3D printer kit so I could fulfil some very specific projects I have lined up this year.
I found a 3D printer kit on line that was very cheap (<£300). It's a variant of the Prusa I3 with a bowden extruder, something I specifically require. It would be very easy for me to knock this printer due to the poor assembly instructions but each time I think about but I find most of my complaints cancel out when I remember how cheap it is. All it really needs is someone in the UK whose built one to answer queries quickly and without the language barrier so I've decided to stock this 3D printer in my own webstore.
Buy your own 3D printer kit from me here.
From here on down I'll be documenting my own build experiences, I set myself 3 nights for building the kit and 3 nights for tweaking and getting a print. This is obviously an ongoing project but I achieved my first successful print at the end of the allotted time and I'm ready to move onto more prints.
The kit shipped directly from China, it weighs 6kg and comes neatly packaged in a cardboad box and pallet wrap so no chance of it getting damp on the journey. The gaps were filled with polystyrene and each component was individually wrapped. The build instructions/software are on a CD tucked inside one of the smaller parcels. The larger parts are laser cut and each of the brackets is 3D printed, a large chunk of the frame is still made with threaded rod and bolts.
The electronics package comes with all the common parts you would expect.
- 12V Power is supplied through a big PSU
- An Arduino Mega 2560 board is the controller
- RAMPS 1.4 connects to the stepper motor drivers, hot components and sensors
- A4988 stepper motor driver chips control the stepper motors
- J Head Nozzle
- Metal Heated Bed
- Stand Alone Print controller, print direct from SD card without a PC
- Large Status LCD displaying the current state of the system
Don't forget if you want to join me on the journey you can now buy the same kit through me.
01 February 2015
Made from 6mm Birch plywood, these arrows will be painted up and attached to a signpost mad Hatter stylee.