Largest post thus far and Happy New Year!

So this is the fifth attempt in getting this update online, if it’s not project progress that makes it outdated at time of almost posting its flaming Microsoft Word crashing when it tries to auto-save. I was going to use the excuse that with starting a new job there hasn’t been enough time to actually get stuck into any serious project work but that would be a bit of a lie. The truth is that the motivation to type out the update has grown less and less as the amount that needed to be updated grew and grew.

In the last update on the arcade machine the second controller panel had just been painted and was drying before the buttons were added and it was installed in the machine. A couple of days later this was done and the buttons were then wired up. One of the modifications that I made to the original design was the inclusion of a M8 threaded behind the front of the player controls, this helped to pull the wooden sides together tight against the metal panel.

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This was a bit of a mission if I’m completely hones as I underestimated the length that the rearmost wire extended off the back of one of the joystick micro switches and ended up munching it pretty good when drilling one of the holes. This then meant that the control panel had to be removed which required the removal of the green trim and a bit of repainting of the wooden sides with the panel was reinstalled.

All that aside once both panels were installed and tested it was time to install the green acrylic behind the panel which will eventually be backlight. I had hoped to find some semi opaque green acrylic that allowed some light to show through but didn’t allow you to see inside the machine but all that I could find on TradeMe was green tinted acrylic. To solve this issue I doubled it up with a sheet of semi opaque white plastic similar to that used on lightboxes.

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The first one of these went in pretty easily with the help of some 3D printed brackets

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The second however fell victim to the old measure twice / drill once curse which then required the purchase of two more pieces of acrylic. The issue that I then faced was that the plastic was delivered approx. 1mm undersize which would have meant that light from inside the machine would spill through the gap left at the side. After stuffing around for a while with black tape and paper I settled on a 2 layer high 3D printed strip which fits perfectly down the side of the acrylic and is invisible enough.

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The final modification that I made to the electronics was the hack of a remote control to turn on and off the stereo and change the input / volume when the cabinet is closed. One of the annoying things about the car stereo is that every time the power is cut and then restored the radio defaults to a powered off state. Secondly when you then turn the stereo back on it’s on the wrong input. I didn’t want to really open up the side of the arcade machine every time I turned it on to turn on the stereo, change the input and set the volume. To solve this I cracked open the remote that came with the stereo and wired it up to several relays which were then connected to one of the nRF24L01 nodes that I’ve been experimenting with.IMG_1028IMG_1030

As a result you are then able to “press” the buttons on the remote wirelessly using a computer / another node to turn on the stereo, switch the input and turn the volume up and down.

A piece of glass for the table top has now been sourced and cut to shape and is ready for install. First the wooden section of the top needs to be cleaned after sitting in the garage for a number of months and have its final coat of paint applied.

Last time on the mower I’d just installed the replacement petrol tap and gasket between the cylinder head and the exhaust with the next steps being the reinstall of the blade, wheels and the handle. This has all been completed with the lawnmower being used to mow lawns with good result several times since, it’s already beginning to collect a few scratches in the paint.

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I didn’t go really go too far with the restoration of the wheels as they’ll soon be removed to convert it into a lawn robot, the height adjustment lever and rods received a clean and the removal of the old paint as its likely they will remain. I did have doubt around the mower running at the correct RPM but a test with a cheap TradeMe tachometer has confirmed that it’s within specification. I still do need to check however that the spring that acts on the governor is set right to allow the engine to respond correctly when the RPM drops as a result of long grass etc. For the moment this project is going to be classed as closed.

I’ve also been playing around recently with some of the WS2811 LEDS that are everywhere these days. The amount of information and libraries that have been written to interface with these makes it extremely easy to connect them to a computer, cell phone or lighting console which has resulted in people making some absolutely mind-blowing art pieces. The first step for me however was ordering a number of different strips and rings for the local supplier to play around with but after coming up with an interesting project using the 12 LED rings I was left with a 1m long strip that I wasn’t really using…

One of the first world problems that I have at the moment is that there is no light switch next to the bed to turn on and off the main lights in the room. This means that there’s always a disagreement over who’s going to be the person that has to turn off the lights and then make their way across the room in the dark. To solve this the 1m strip was attached using the 3M tape provided to the bed end was connected to a Arduino clone and Bluetooth to serial module which was mounted on the side of the bed end in a 3D printed case.

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An app was then whipped up using the ever useful MIT AppInventor software which allows you to control the strip with an Android phone.

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When opened, the app immediately tries to connect to the Bluetooth module and then presents the user with buttons to select either the left hand side, the right hand side or the entire strip. Four sliders then allow you to set the Red, Green and Blue channels or all three at once using the white slider.

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There is also an “All Off” button to turn all of the LED’s off at once. In all the project only took a night to build and then program. Eventually the plan is to replace the Arduino and Bluetooth module with one of the nRF24L01 nodes to integrate it into the rest of the node network.

The second project that I’ve been working on with these LED’s uses the 12 LED 90 degree sections that can be soldered together to make a 60 LED ring. Quite a convenient number to be honest.

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The first step was soldering the ring together, a flat surface really helps here to make sure that the ring isn’t twisted once soldered together. That being said there is enough give in the three solder joints between each section to straighten it out afterwards. To provide extra bracing to the ring and to eliminate having to use wires as such I built a bracing frame to connect to most of the 5V connections on the back of the ring and then another to connect to the GND points. The GND braces actually sit about 1.5mm further back than the 5V frame and are isolated with small pieces of heat shrink where required. I quite like using bare copper wires when possible for things like this as not only is it reasonably strong but also conducts (duh) and looks quite cool.

Once this was complete the five components (Arduino clone, RTC, capacitor and 2 x resistors) that were going to be used were positioned and then soldered to the bracing frames to mount them and provide the 5V and GND connections. The SDA and SCL connections were then made to the RTC as well as the DIN connection to the first segment on the ring.

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After this it was time for testing. At this point I hadn’t put the power connectors on the clock yet but having a frame that was actually the 5V and GND rails made it extremely easy connect the power supply with the help of a couple of alligator leads. Success LED ring works with the demo sketch on the Arduino. I’d previously used this model RTC on another project and so was able to copy the code that interfaced with the RTC from that which saved some time however when trying to run it on the Arduino for some reason the RTC wasn’t running. Poking around with it mounted achieved little and so it needed to be removed from the frame without damaging either the RTC or the bracing frames. Once complete however temp headers were soldered on and it was tested with several different Arduino models. None worked.

At this point I was thinking that perhaps I’d received a dead model so I started tracing out the connection on the PCB. All were fine. I then replaced the backup battery and ran through them again to find 0V on the battery input pin on the RTC. After confirming that the battery did in fact have charge I had another fiddle and figured that perhaps the positive connection on the battery holder wasn’t making a proper connection. Scratching some of the surface off didn’t solve the problem but shoving a piece of tin foil in did. After testing that the clock was now working properly I replaced the tin foil with a pad / blob of solder and returned the RTC to the clock frame. Note: despite having power applied to the +5V input on the RTC the backup battery appears to need to be present for operation. Who figured?

A wee bit of further programming later and Voila, finished clock. Hours are represented in green, minutes in blue and seconds in red. After 6pm at night the clock display turns off and then turns on again at 6am in the morning.

(Sorry for the vertical video, I know I’m a bad person)

On the lathe a number of parts have been painted and installed to the point that there is one more part needing a second coat to reassemble the headstock. Both the front and back belt guards covering the longer of the two belts have been installed as well as the countershaft, swing arm and V cone pulley. Both of the bearing caps and the back gear eccentric assembly have also been painted. Once all the parts are ready the headstock will then be assembled, after that the next step will be to paint the other belt guard, back gear lever and tumbler gear lever…

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(Leap forward in time two weeks) Since typing all that out the headstock got its second top coat and was installed on the bed. It was a relief to finally get this done and remove the masking tape that has been on some of these parts for the better part of three months. Now that the weathers warmed up a bit it’s so much easier to get paint to dry which has vastly sped up progress. A few days after the headstock was installed the drip feed oilers were cleaned out and attached to the bearing caps. The backgear eccentric assembly has also been installed and loosely connected to the lever on the outside of the headstock. Once the spindle has been shimmed up and the correct position of the backgear has been determined then the lever will be tightened up onto the backgear eccentric assembly. IMG_0904IMG_0906IMG_0916

Leap forward yet again…. The headstock has now been finished with the spindle installed and shimmed up. The back gear has been positioned and tightened and tested and runs pretty nice. The lathe is at the point where it can be used to an extent again and so as opposed to having to polish the hand wheels in the drill press I’ve been able to do them in a proper chuck without having to mount them on a piece of metal rod to mount them in the drill.

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Unfortunately I discovered some time ago that the same colour paint from the same manufacturer differs depending on whether it has come out of a tin or a spray can. Normally I guess you’d use one or the other however at the start of the project I used a couple of cans on the first few parts before switching to a tin to do the bed. Since then I’ve stayed with the tin as the finish is actually better and it’s a lot more economical. The problem (to me) that this created was that the tailstock was a slightly different shade of grey to the rest of the lathe and due to its position (all the other sprayed parts aren’t readily apparent) a bit of an eyesore. To fix the tailstock was disassembled and wiped down with IPA before receiving a coat of paint from the tin before being reassembled and reinstalled. The oil nipple on the top has also finally been screwed on (small job but never seemed to get done) with the hand wheel for the tailstock receiving two light topcoats.

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When painting the first hand wheel I went with a mask and paint approach, masking off the outer polished section prior to painting the inner. The tailstock hand wheel has a slightly different profile between the polished and painted parts which made the masking attempts less than ideal. In the end I abandoned masking and used model brushes to paint the border between the painted and polished sections. This is probably the same approach that I’ll use for the remaining hand wheel as well.

The tumbler gear assembly has also been painted and reinstalled along with the leadscrew bracket assembly at the headstock end as well as the change wheel quadrant. I know that the bracket assembly is a different colour, this is because it’s new and I can’t bring myself to pull off the factory paint and repaint it in a matching colour. I realise that this may sound hypocritical in light of the tailstock repainting requirement however I’m justifying it as an homage to the original colour.

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The leadscrew has also been reinstalled but is hanging off a section of wire at the tailstock end whilst the bracket at this end receives its coats of paint. This will then be reinstalled with the associated spacers and nuts etc on the leadscrew to the complete this section of the lathe.

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This has now been done, the bracket install went pretty easily although the top coats were a pain in the butt. Its been stupidly hot here recently and so the paint has been drying too quickly for it to flow out and make a smooth surface. Eventually a passable finish was achieved. The full geartrain was run today for the first time with most pleasing results.

Moving onto the carriage assembly, the topslide has been installed on the topslide base with the gib strip adjusted to remove slop, this has then been installed on the crosslide with the crosslide endplate receiving its first coat of paint two days ago. The carriage proper has been stripped of paint completely and will be cleaned of the protective oil layer, masked and painted probably this weekend.

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For the last couple of weeks the amount of work that still needed to be completed (read repainting) still seemed to be an obscene amount. After making inroads on the carriage however the end seems to be a lot closer somehow. Both the belt guard that sits between the swing arm and spindle and change gear cover still need to be painted however I’m hoping to bead blast these which should speed things up a bit.

The final project that I’ve been working on is the construction of a Shapeoko2 which is mostly complete aside form a number of modifications that are required for the end stops to work properly.

Ive only got three pics of this sorry, one of it in the box,

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one of it out of the box,

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and one with piles of junk gathering on it because my Dremel has crapped itself

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In general the construction of the frame went fairly smoothly and was completed in a couple of nights although tapping all the aluminium extrusion got very old very quickly. From first inspection it looks to be a fairly well designed machine with the following comments.

  1. The screws that attach the gantry to the Y motor mounts could be longer. Compared to the rest of the screws that went into the ends of the aluminium extrusions these were oddly short. This combined with the fact that the holes are tapped into aluminium didn’t offer too much strength (note only in my opinion). I ended up replacing these with longer screws for peace of mind.
  2. Some form of indication as to how to beset attach end stops wouldn’t go amiss. In the end I had to print a number of different brackets (6 in total of 5 different designs) in order to mount all the end stops.
  3. Make the end stops NC by default. This I think would solve a lot of the issues that people have with the end stops triggering from motor noise and would certainly be a lot more fail safe
  4. Someone really needs to have a look at software such as Repetier Host or Pronterface and come up with a solution for the Shapeoko (or if you know of one then let me know please!!)

These last two points have been a real pain in the ass…

Firstly it’s interesting to see the difference in maturity between the PC software for 3D printers and for CNC machines running GRBL. Taking Repetier Host or Pronterface for example you have two pretty polished pieces of software that works with a number of different firmwares and offer a lot of functionality. Looking at similar software but for CRBL based CNC machines the pickings are a lot thinner with it seems to be greater “width” but not as much “depth”. What I mean by this is that it appears that there seem to be a wider range of PC side programs but at the expense of functionality and usability. Issues demonstrated by this approach have been identified as follows

  1. The “$#” ordering of the settings seems to change between the different versions of GRBL with new settings displacing current settings in the numbering plan. This caused issues with a number of programs that had the settings numbering coded into the program which then didn’t match the different versions of GRBL. These programs at time of writing have not been updated yet.
  2. The requirements for a federate to be included in move commands changed within different versions of GRBL as a result the jog functions on some of the software didn’t work.
  3. Not all software provided button access to commands such as “Home” and “Unlock” Whilst I accept that you are able to issue these commands using “$H” and “$X” it seems odd that these were omitted considering how central they are to operation.
  4. No one bit of software seemed to offer good machine jog controls, visualisation and easy access to the settings in GRBL
  5. Half the software had the machine moving in negative space as it moved away from the home positions, the other half had it moving in positive space with no apparent setting in any of the software to change this. I accept that this isn’t functionality provided by the majority of the 3D printing software but at least the approach is consistent.

I think that there is massive potential with GRBL to have a stable low cost platform to run homemade CNC machines off but at the moment this shotgun approach to PC side software hasn’t resulted in the full potential to be realized in my opinion. I’ll keep looking however and update below as this changes.

Secondly the decision to go with NO end stops for the GRBL shield is interesting and seems to cause a lot more issues compared to NC end stops as well as being less fail safe. Numerous blogs, forums and my own experience with NC and NO end stops on 3D printers have indicated a greater number of issues with noise and false triggers with NO end stops over NC end stops so I’m really sure why at the expense of the above the design choice was made to go with the NO option. It seems from what people are having to do to fix the issues with the NO end stops that it would have been a lot easier to have NC ones in the first place.

In my instance I wasn’t able to easily modify the GRBL shield I had to run with NC end stops so I had to resort to adding extra resistors and capacitors to pull-up the end stop properly and remove enough noise from the end stops for the machine to run reliably without the end stops triggering all the time. I haven’t yet run an extended job on the machine yet so it’ll be interesting to see whether these modifications will be enough or whether more work will be required to get it to function properly.

In conclusion with the Shapeoko I kind of get the impressions that it’s less of an “Out of the box” product than it claims to be with some obvious shortfalls in the software and end stop department. Despite that the design works well and has promise. In all, for the price it’s a pretty good option.

First game played

So since my last update as usual what progress has been made has been across a number of projects but not really anything pivotal. On the Lathe front several sections have been cleaned for painting and then install. The swing head assembly is ready now for masking as is the change gear guard backplate and the front and rear bearing guards.

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Once the swing head assembly has been installed the belt guard will be remounted as well as the first belt and the motor. The bearing guards are still waiting on the headstock to be painted.

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Several more coats of paint have gone on the top of the arcade machine. Some troublesome screw holes have required a lot of sanding and repainting to cover them up but they’re almost gone. A couple more coats on the top and I’ll focus on finishing off the sides in preparation getting a sheet of glass cut for the top. The first control panel was wired to the Jamma board in the weekend and then rewired as it had initially been connected to the player two connections as opposed to the player one connections.

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(Screw holes can be seen in the middle of the top reflection of light)

The car stereo that is driving the speakers was also wired up as well as a couple of fans for some airflow. I’m still going to have to check that the screen doesn’t get too hot lying down as that the majority of the cooling will be passive and to having the screen lying down won’t exactly be the most efficient.

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The first couple of games were also played with good results.

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The second controller has now been drilled and had several coats of paint applied so once this has dried the controls will be mounted and wired into the player two connections. After that the Perspex panels behind the controls will be mounted.

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Once the glass has been fitted to the top section that will be installed and the height and position of the screen will be adjusted to fit

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The petrol tap for the lawnmower arrived the other night, once installed the mower was filled with petrol with no leaks. The mower also started pretty quickly compared to the first time and after letting it sit overnight it started the next morning after only a couple of pulls. A cork gasket has also been installed between the mower deck and the engine which means that all three of the initial issues identified after it was initially restarted after being stripped down have been addressed.

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I still need to strip and paint the wheel mounts and height adjustment rods, once that is complete they’ll be reinstalled and the wheels and blade chucked back on. I still need to check that the carb and governor is running properly. At the moment the Heavy / Normal selector lever does nothing (although it shouldn’t really until the engine comes under load, all it seems to do is give preference to a more open throttle position) and the governor seems to be doing its best to throttle the engine back. I’m betting though that this is because the blade has not been installed. Hopefully both the air resistance of the blade spinning and the resistance between the blade and what it’s cutting should load the engine enough that the RPMs drop enough for the governor to control the throttle properly. We shall see….

One of the annoying issues that I’ve had with the motors used on my 3D printers so far is the motor shafts have a 4mm diameter as opposed the more standard 5mm shaft. This basically means that any of the readily available GT2 gears with either a 5mm bore or an 8mm bore don’t fit on the motors. I don’t feel like paying moonbeams either for a 4mm bore gear as investigations thus far have revealed them to be 3-4 times the cost. Thankfully the majority of the motors thus far have come complete with GT2 gears already fitted to the shafts and so I’ve been able to use those. On the Kossel however I decided that these gears wouldn’t be suitable, despite the fact that they have a low tooth count which helps with precision, they don’t have a flange on the outer edge to keep the belt from slipping off. On the shorter belt lengths on the I3 and the V2 I’ve managed to address this issue with careful alignment of the motor, idler bearing and carriages the Kossel doesn’t really have this amount of customization when it comes to the position of these components.

To this end I decided that the best option would be to order a low tooth count GT2 gear with an 8mm bore and then make a spacer to adapt the 4mm diameter of the motor shaft to make them fit the gears.

A perfect job for a lathe you might say! If only I was a month further along in reassembly I would reply. Bugger.

As a solution I went with an old trick. Mount a drill in a drill press the wrong way around, lower the bit into a vice and clamp, release the chuck and gently raise the press again. Insert the work piece, turn on the drill and slowly lower onto the drill. If you take it gently the drill should self-center and drill down the middle of the work piece. Imagine a lathe standing up on end.

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It’s less than ideal and a bit of a pain to get everything aligned but I managed in about 15 minutes to turn out 3 spacers with a hole only .1mm off center, should be good enough.

Until next time

 

The Mower Runs!

One of the big concerns I had with taking the mower engine apart was whether it would run once it was all back together again… After replacing all the gaskets, finishing the cleaning and then remounting it 3-4 minutes of yanking on the starter cord caused it to fire up and settle into a regular idle. Three things became apparent very quickly. Firstly there is a decent leak from the petrol tap down onto the carb and then onto the mower deck so this needs to be replaced. Secondly there is a leak from the bottom of the carb where the drain valve is. This is basically a small rubber grommet held to the bottom of the carb bowel with a spring so it’s not surprising that its leaking. Finally there should be one more gasket between the engine and the silver muffler bit that bolts onto the mower deck, then it won’t belch smoke, oil (maybe I poured too much in) and other crud out onto the top of the mower deck.

The carb bowel issue was perhaps the easiest to fix, remove the old rubber bit and spring completely and then replace with a stainless steel m3 screw with a nitrile rubber washer. Whilst this means there is no way now to drain the carb it has stopped the leaking. Some decent legwork on Google located some new old stock of petrol taps and even more legwork located a guy in Florida that is selling more new old stock of the exhaust gaskets.

The petrol tap is on the way at the moment, the gaskets still haven’t surfaced at the YouShop depot in the US yet though :S

We’re basically at this point at the moment (the shroud and gas tank were mounted but needed to be taken off to fix the carb and I decided to leave them off until the new tap arrives).

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On the lathe the motor mount has now been mounted as well as a few other parts (added after the photo was taken) Next step will be repainting the swing head assembly and refitting that. Once that is complete then the belt guard and motor can be remounted.

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The Arcade machine received its paint over the last week and with the exception of some troublesome screw holes on the top surface the painting is now complete. The green T-slot has been inserted into some of the slotted areas as has one of the control panels.

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This control panel has been wired up but not yet connected to any of the rest of the gear yet. A power supply and the JAMMA board have both also been mounted.

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6 more of the wireless nodes have been completed this week as well bringing the total working nodes to 12 good and 1 slightly suspect node (called such as it was the first one built and initially had the power connected the wrong way… It works but still)

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On the programming front all 12 good nodes work on a network now communicating back and forth to the base node. The single digital pin and both the analog pins that are broken out onto the node header on the remote nodes can be controlled from a small (and still WIP) bit of software on a computer connected to the base node. The remote nodes can also report back to base the voltage of their power supply and temperature. Basically a serial string sent to the base node causes a message to be sent to the desired remote node toggling the pins or flashing the LED’s for identification purposes. At the moment the focus is now on developing the PC side software and building a higher power base node.

I’ve also started building one of these…

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Lawnmower Engines, Mesh Networks and Lathe reconstruction commences

With the mower deck now all painted aside from the flappy chute thing I could now start to reassemble it. First step was bolting the mount for the exhaust and the motor back on to the deck. I had elected not to paint this and I think that it looks quite nice in contrast to the blue. When I had initially started spraying on the blue the color was nowhere near the color of the cap and I thought there was no way that it was going to change the amount needed, but thankfully after three or four coats its come up a deep blue that should go well with the red shroud.

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After that it was a case of squirting the gasket stuff into the 2nd half of the exhaust and then letting it dry before bolting together.

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Apparently this Blue Max stuff isn’t recommended for exhaust applications but whats the worst that can happen, It’s good for the temperature and is only a lawnmower after all.

Next step was tackling the dirty lawnmower engine shaped elephant that’s been sitting in the corner since the project started… I don’t think it’s ever been cleaned based on the amount of built up grass, dirt, oil, and unidentifiable gunge on most surfaces.

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This is after about 30 minutes of gunge removal. This and the next few pics were taken to increase the odds of getting it back together again.

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Two hours of rags, brushes and petrol though gave the following result, quite an improvement.

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I’m now waiting on some gaskets to arrive before further re-assembly, when I got the motor there was a two stroke leak from somewhere and I figure whilst it’s mostly apart the gaskets may as well be replaced to hopefully stem that. More to come when that happens.

Something else that I’ve been looking into recently is home automation / smart home systems. It seems that there is a lot that is coming out in this area now with the ease of access to smart LED bulbs and wireless door locks etc but at the same time not anything that is reasonably priced to implement and able to cover both a wide range of input methods (sensors, human control…) and outputs (lights, TV, blinds, arcade machine…) I suppose because any system would need to be fairly bespoke and therefore pricy. Since the interface between a micro-controller and whatever its controlling would seem to be the easy part (and also the part that would require customization depending on the output) I figured a good place to start would be with the network (I also decided that I wanted something wireless and reasonable easy to retrofit).

Looking around the internet I found a blog about how to network together a whole lot of Arduino nodes with the nRF24l01+ radios. http://maniacbug.wordpress.com/2012/03/30/rf24network/ This method ticked most of the boxes that I had, low-cost per node, low power consumption, easily expandable and versatile in regards to inputs and outputs.

To that end, after making a tweak to the design I sent the board off to iTead Studio to have a number of the boards produced, the bonus was that I was able to fit 4 of the nodes on the 10 x 10 area ordered from iTead resulting in 40 individual boards (once cut up…). These arrived on Friday.

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A couple of days before the boards arrived I had received new toys (the components) from Digikey so no time was wasted soldering one up to test before putting together another 6.

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Bootloader burned thanks to Arduino ISP sketch.

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I’m still waiting on some headers to arrive from China and then Ill plug the radios onto the boards and have a play with the network layer that maniacbug has put together before tweaking it for my own purposes.

On the lathe front, re-assembly has now commenced on the bed. Over the next couple of days as parts dry they’ll be fitted back on.

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It seems that the parts that were sprayed don’t have the same level of gloss as the brush painted parts but aside from that the color of the two seems to be a pretty good match.

Arcade machine has not been plastered and after sanding tonight or tomorrow painting can commence!

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Electrolytic Rust Removal

Whilst stripping and spraying the lathe I’ve had the need to remove oil, grease and paint from a number of parts. Most of these have been small and made from some form of alloy and so have had to have either been bead blasted (none with bearing surfaces) or chemically stripped using a product called “Tergo Strip”. This stuff is amazing, brush it on and then watch the paint flake off. Spray with a waterblaster, dry, scrub with detergent, dry and then paint.

The Lathe bed however has proved to be a different mission however with the paint on this part proving to be a lot more of a pain to remove. The ways mean that bead blasting is out of the question and the requirement to wash Tergo strip off with water opens the door to flash rusting in all sorts of places (this part is not made of alloy). Combine that with the fact that the thing weighs at least a good 40 kg and there’s a problem.

The solution proved to be electrolytic rust removal, a process that seems to be so simple and so effective that I’m still slightly suspicious of it. Basically you suspend the rusty part in a container of water + washing flakes (sodium carbonate), hang a piece of iron in there as well, connect a battery charger to the rusty part and the chunk of iron and watch the rust disappear.

My implementation of this process started with a 160L plastic drum purchased off Trademe, some rebar and a computer power supply. The rebar was cut into 6 lengths, had the ends ground clear of any rust and dirt and then hung around the perimeter of the drum.

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Copper wire was then would around the ends of the rebar and taped to stay in place.

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Four Square provided a box of 44% soap flakes which was then dissolved in 10L of hot water before being poured into the drum with cold water from a hose.

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The Lathe bed was hung from the roof initially with a ratchet tie-down and then using a spare boat winch to facilitate easy removal for inspection. Car jumper leads then provided the connection between the computer power supply GND and +12v1 rail and the lathe bed and copper / rebar ring.

Powering the power supply on results in a slight fizzing sound and bubbles on both the lathe and the rebar (hydrogen and oxygen apparently). 5 minutes of bubbling results in rust scum such as this,

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with a further hour resulting in this cocktail

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Initially the current through the system was higher than was preferable so some of the solution was siphoned off and replaced with fresh water.

Already the paint has started to flake off and any areas that had developed slight rusting have come clean which is very promising. I plan to remove the lathe later tonight after soaking for most of the day and give it a good scrub before replacing it for another soak.

After that it will be a case of cleaning it off and displacing the water in a manner that will allow me to repaint (not sure on this one yet) before masking and getting a base coat on it.

On the arcade front the woodwork is pretty much finished, just waiting on the door that needs to be installed in one side before painting.

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The LCD mount ended up a bit different to that in the plans, basically the screen sits on the mount below with the help of a 3D printed VESA mount. The bolts allow the screen to be screwed up and down whilst the threaded rod allows for positioning on one axis.

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Tabletops, Vases, Voltmeters and Guitar Pedals

Prepare for another multifaceted update

1) Tabletops

Much searching around Auckland for the required 25mm sheet of plywood took a week of unanswered emails, unhelpful sales staff and staff who claim to have stock until you turn up to find that they’re completely out. When calling one store to ask if they had the product in stock one really “helpful” sales guy even replied “If my staff spent all their time running around the store seeing if we have stuff in stock they wouldn’t have time to do their proper jobs”. Considering that the store solely sold plywood and if they had it in stock I would have brought it I’m not exactly sure what the staff was doing that was more important than making a sale. Thanks non named plywood merchant located in Penrose…

All that aside eventually a sheet of plywood was located and then cut into three sections with a blunt handsaw to fit in the back of the car. This then had the outline of the table top drawn and cut out of it. Next step will be cutting out the hole for the LCD and mounting it to the cabinet. Aside from that the control panel braces and a couple of air / speaker vents are all that will be left on the wood working front. After that a final bog and sand before painting.

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2) Vases

I’ve also started to experiment recently with thin wall 3D printed objects to see how well the printer did printing large single extrusion objects. The main concerns that I had were related to the piece glooping down because it didn’t have time to cool or the layers not lining up, which when printing with a .35mm nozzle is quite important. Aside from a few artifacts on one corner the parts printed quite well however, I’m happy enough with the result at the moment although ill probably fiddle with the density of the walls at some point to make them more solid.

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One interesting discovery I did make however was a strange translucent goopy liquid that started leaking out of the hot end after a while of printing. It’s possible to wipe this off before a print and even after 2.5 hours of solid printing it’s not really an issue but I’d still like to work out what is happening. Seeing as it looks similar to the stuff that ends up inside the V2 nozzle between hot end services I’m inclined to believe that it’s either a result of the temperature settings not being quite right and so the filament is doing something weird when melted and separating somehow or the filament has absorbed too much moisture and that is what is separating out when it is heated. As near as I can figure this is leaking out of the hot end where the nozzle threads on and is then oozing out between the nozzle and the heater block.

3) Voltmeters

Over these next two weeks ill need to spend some time preparing the shopping trolley for Eastercamp. Thus far I’ve replaced a button mount that has snapped off with a beefier version and finished off the Lo-Jack code on the GSM and Comms Nanos. Now sending the correct string to a cellphone number will cause the trolley to TXT you back a Google maps link to its position as determined by GPS. At the moment the number to reply to is hard-coded to one cellphone number but the long-term intention is to have it reply to the number that queries it.

Additionally I’ve added a couple of voltmeters in a printed enclosure to the front of the trolley. These are completely separate from all of the rest of the trolley electronics, connected directly to the batteries via a toggle switch to power them on and off. Testing with a multimeter confirms that their reading are accurate.

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(Mount in the middle without screens)

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(and Screens)

Still remaining on the to do list is an investigation in to the throttle code (sometimes the trolley takes off on its own) which I suspect will require the addition / modification of a greater dead spot for All Stop. Sometime next week one final yet to be unveiled cosmetic change specifically for Easter Camp will also be completed.

4) Guitar Pedals

Recently a friend asked me to look into making a cheap copy of a midi controller / guitar pedal to control a Strymon Timeline “some-sort-of-multi-effect-/-looper-pedal?”. The original controller pedal can be brought online for approx $150 US but that is before shipping from the States and any import taxes etc. I’m afraid I don’t have any photos of this project as it was completed in two days but the concept is as follows.

On the top of the pedal there are three foot switches evenly spaced across its width with an LED above each. The left and right LEDs light up with the switch below is pressed whilst the center LED is an RGB one that changes color to indicate the mode that the pedal is in. Pressing the center foot switch cycles through the modes changing the function of the left and right buttons. In each different mode a press and/or hold and/or release of the button sends a MIDI message out the 5 pin DIN port on the back. Pressing and holding the center switch sends a particular message independent of the mode. An Arduino Nano inside is the brains of the lot

The most “fun” part of the project was fiddling around with the differentiation between a press and hold especially considering the foot switches had a lot of bounce that needed to be programmatically taken care of. The basic functions presented by the controller pedal include scrolling through the Strymon presets, controlling the looper record and playback functions, bypassing (something) and controlling the “Tap” input and “Infinite Repeats”. In the end the project was a success however coming in at around half the price (before shipping) of the pedal available online.

Link

4The gap between my last post and now has been filled with sporadic bursts of activity curbed mostly by the amount of time that can reasonably be spent on projects and whether I’m in the right frame of mind to focus on something that requires a degree of patience and accuracy. All that aside the intervening time has been spent on three particular projects.

1) Arcade machine.

I’ve wanted to build one of these for a while and with the I3 finished and most of the parts already collected it seemed like an ideal opportunity to tackle this one once and for all. A flurry of jigsawing, gluing, screwing, bogging and sanding quickly turned this

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into this

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For anyone interested the plans can be found for free here.

At the moment the base of the table is pretty much finished, all that is needed wood wise is the table top and the braces for the control panels. The top of the cabinet only needs a quarter sheet of 25mm thick plywood but no one seems to sell sheets that small and the people who assure you vehemently that they regularly have offcuts of that size in that thickness never seem to … If anyone knows a good source for less than full sheets or somewhere with a price so good that I could buy a full sheet then I’d be greatly appreciative.

On the control panel front the diagram for the plans was sent off (and then sent off again because everyone bar one source seem to be too lazy to convert 3 measurements from imperial to metric) to 6 places that do sheet metal fabrication so I could get a couple of blanks knocked up. Eventually the quotes started trickling back with prices ranging from $48 for two to a whopping $160 +GST. In the end I settled on the supplier that could be bothered tacking the imperial conversions (even though I later sent them the plans in metric). They responded quickly, had a good price and did a good job. Thanks Classic Sheet Metals in Henderson.

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These blanks were then drilled to a template cobbled together from various other arcade panels and the buttons and joystick were then test fitted

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and given several coats of satin black spray paint before the buttons and joystick were refitted

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2) ARCredit

Turns out that two player machines need two coin slots. Guess that makes sense. This caused a problem as the coin slot thingy that I had only had one slot and the supplier no longer sold identical units. Average.

Anyway coins are on the way out, contactless payments are where it’s at so introducing ARCredit.

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Arduino Nano with RC522 RFID reader and the obligatory JY-MCU Bluetooth Module.

This particular reader was chosen due to its low-cost and eBay availability, this came at the cost of having a less than ideal method of communication with the MCU namely SPI. The even more annoying this is that the IC that the reader is based around also has a serial connection, it’s just not broken out. Instead then of issuing simple strings out a software serial port I had to resort to using a specific library created to communicate with this reader, but unfortunately at some point written in Italian? with not much basic documentation. After spending a couple of days trawling through the code and trying different things I managed to get the code working well enough for my specific application and another couple of days of fiddling around had the turd fully coated in glitter.

Basically the reader works with the Mifare chips which you can get in token or card form. Using a custom access key the reader pulls the factory serial number and a 16 byte string from two different places on the chip and makes sure that they both match the strings written into the code. A third location is read with a single byte retrieved which represents the number of “credits” remaining on the token. In practice a player would hold down their “coin insert” button on the arcade machine and swipe their tag. The Arduino would check that the tag is valid and then trigger an output pin to send the coin insert signal to the arcade emulator. Each successive swipe deducts one coins worth of credit from the tag and then triggers another coin insert signal. The software has a customizable pricing structure in which you can define the number of credits that are taken off any particular tag each time the token is swiped.

The Bluetooth module is there for the purpose of adding credit to the tags. Connect a cellphone running the ARCredit software and send the appropriate string to the Arduino. The next tag that is swiped will then have its balance set to the value sent from the cellphone.

Once the rest of the arcade machine is finished the reader module will be mounted to the a perspex window in the side of the cabinet with the Arduino and Bluetooth mounted properly on a PCB elsewhere inside. As usual the code is up on Github, any misuse and token fraud will be met with severe repercussions.

3) Battery Charger

I think I’ve mentioned before that the battery charger in the Shopping Trolley is a little suspect. I’m sure that F&P make some good stuff and that the original charger is perfectly good for the stock batteries but ever since I put the new double capacity batteries in the charging light has always been on and the battery level indicator has been a bit suspect. The last thing that I want to do is over discharge the batteries and shorten their life

To remedy this and protect the investment made in the batteries I decided to fiddle around with the charging system, specifically setting it up to better balance and maintain the batteries when the trolley isn’t being used.

As a result 6 massive-key-switches-of-doom have been added to the foot well. Switching the three on the right connect the batteries in series to the rest of the system for riding around where is switching the three on the left connect them in parallel for charging.

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The string is there to make sure that only one side can be switched on at once and even though the switches each came with one key (making 6 in total) three have been destroyed in the fires of Mt Doom (hidden away where ill never be able to find them). This combined with a healthy dose of “NEVER EVER DO THIS [AGAIN]” to any potential operators should prevent potential 12v deep cycle battery short-circuit fun.