RepRap Morgan was recently awarded the Gada prize, which was the first time I had seen a “SCARA arm”1 robot.2Reading Hackaday lead me to read about RepRap Wally, another SCARA based robot.3 Anyhow, My favorite part about this robot is that it boasts it can print parts for larger versions of itself.
While building more 3D printers is, perhaps, a noble goal – democratizing production and all that – actually working to churn out parts is a dull business. On the other hand, the idea of a robot capable of building increasingly larger iterations of itself is incredibly amusing. As is the idea that a robot could build smaller and smaller versions of itself.4
Of course, this then makes me think of a chain of robots – one set making ever larger and another set making ever smaller robots… robots all the way down.
Outside a MintDuino, a book is a man’s best friend
It was hard for a beginner like me to imagine that an Arduino actually requires a whole lot less than all the stuff you would see on an Arduino Uno. Assembling a MintDuino – and slowly pulling parts out to see what was really necessary – helped me understand what was truly critical to its operation.
Inside a MintDuino, it’s too dark to read…
I found it useful to know what the (near) minimum necessary components of an Arduino were so that I could build a small project directly around just the chip and whatever critical parts were absolutely required to run the circuit.1 I wanted to build the circuit as small as possible – not to save on parts or cost, but to make sure everything could fit into an Altoids tin.23
As a side note, there is a very definite monetary benefit to figuring out how to build a minimal Arduino compatible device. A brand new Arduino will run you about $30 – whereas soldering a chip into perfboard with the least amount of parts required would probably only cost you about $9 or less if you source the pieces carefully. While an actual Arduino form factor makes a lot of sense when you’re using off-the-shelf shields, it’s not nearly as important when you’re building a very simple or completely custom project that you don’t intend to take apart. And, when you’re talking about leaving a chunk of electronics in a project, it’s a lot easier to leave $9 in parts inside rather than a $30 Arduino board.
Here’s what I found to be the (near) least number of parts and (basically) the smallest configuration for the programming MintDuino:
The (almost) minimum you need to upload an Arduino sketch
This is the “almost” minimum since the configuration above includes (1) a red power indicator LED and a 220 Ohm resistor and (2) a red wire, another red LED, and another 220 Ohm resistor for running the “Blink” sketch. Once you remove those parts, you could still upload a sketch to the Arduino – but it wouldn’t be able to do anything. You’ll notice that this configuration doesn’t even include the usual reset button for the Arduino.4 It’s not pictured, but you’d also need a way to communicate with the Arduino, such as a USB cable plus FTDI Friend or FTDI cable.
Here’s what I found to be the (near) least number of parts and (basically) the smallest configuration for running a sketch on the MintDuino:
The (almost) minimum you need to run an Arduino sketch
Again, I’m qualifying the statement with an “almost.” This nearly minimum configuration above again includes a red wire, another red LED, and another 220 Ohm resistor for running the “Blink” sketch. You could remove all of these parts and connect whatever else you wish the Arduino to do for you. While the power LED indicator is useful to know that your project has power, I could see some situations where you wouldn’t want it – such as for a project that needs to work in the dark without drawing undue attention to itself.
Besides fiddling around yanking parts out of my MintDuino to see what would happen, I also found some interesting tidbits about building a minimum possible Arduino. If your project is tight on space or you are tight on parts or budget, you might find some of the following useful:
This tutorial points out that you don’t really need the crystal/clock and two capacitors for your Arduino if you use its internal clock. To use the Arduino’s internal clock, you would have to accept two important compromises. First, you would have to accept that the internal clock is not as accurate as the external clock from these additional components. If timing is important for your project – perhaps something that deals with communicating with another device in some fashion or is otherwise time-critical – you don’t want to do this. Secondly, you would have to use a different bootloader other than the Arduino bootloader for your project. The author of the Instructable suggests the Lilypad environment would be reasonably compatible with an Arduino project, but would make use of the chip’s internal clock. (He also suggests you may or may not have to disable your board’s auto-reset feature).
I’m still very new to this whole Arduino thing, so if you notice something wrong here, please let me know so I can fix it.
My very next Arduino project is going to be something that fiddles with my television’s IR (infrared) control codes. You can expect some definite wackiness soon…
Default Series Title
Since I wanted to include a picture of the MintDuino inside and out, I couldn’t help putting a spin on this classic Groucho Marx quote. [↩]
I ended up using the Mintduino tin – and actually recycling some of its packaging into the project as well [↩]
I discuss this more below, but I don’t think you need the crystal and two capacitors for the “external clock” functions of the Arduino if all you’re doing is uploading a sketch. [↩]
My first real foray into tinkering with an Arduino began a few weeks ago with a MintDuino. About two years ago I contemplated trying one out, but I never pulled the trigger. This was due to a combination of decision paralysis, a very short attention span1 , and a plethora of other projects that were always vying for my2 attention.
Overall, I think this was a good place for me to start learning about Arduinos.3 The nifty thing about the assembly tutorial for the MintDuino is that it takes you slowly through the creation of an Arduino. I learned a surprising amount from assembling this little breadboard Arduino – more so than I ever did by just making an LED blink on a regular Arduino Uno.
The first thing the tutorial does is show you how it converts the power from a 9 volt battery into the 5 volts that an Arduino would use. I found this incredibly useful. Even if I had stopped reading the tutorial at Step 7, I would have learned that with some capacitors and a “voltage regulator,” I could create a system for converting power from a 9 volt battery into something I could use in a different project. Sure, I didn’t learn how these parts made that happen, but this was something I could put to use immediately, if I so chose.
The second thing the tutorial takes you through, at step 9, is adding a “crystal.”45 This wasn’t particularly useful to me – except that now I know how the Arduino is able to keep time. While doing some ‘net research on what constitutes a bare-bones minimal Arduino, I discovered that it is possible to omit the crystal and two capacitors in favor of the chip’s internal clock.
The third thing I learned from this tutorial, at Step 12, is what appeared to be the bare minimum MintDuino setup required to run a program that was loaded onto the Arduino’s chip.6 Now, it’s possible to remove several more pieces and still have a working Arduino. If you just had to have an Arduino with an absolute minimum of parts (I’ll get to why later) you could pull the red LED, the 220 Ohm resistor, the black wire going to the red LED. The result would be a pretty minimal Arduino that didn’t have a status/power LED, but could blink a single green LED. Remove the green LED, the red wire going to it, and the 220 Ohm resistor going to the green LED, and you have a really stripped down Arduino – that can’t do anything. But, if you were to design your own Arduino project, you could build this minimalistic Arduino, add connections to whatever additional parts you needed, and solder it all together.
By the time I got to Step 17, I learned the connections to the ATmega328 necessary to program the chip with an Arduino program.7 This was interesting to me because it meant that any circuit that I wanted to design, but still have the capability of reprogramming at a later date, would have to have these connections. However, it would probably easier to add a 28-pin socket or 28-pin ZIF socket to your project so you can remove the chip, reprogram it, and replace it without much fuss. ((I mean, why add a bunch of wires you only need for reprogramming to a project when you can add a little socket?))
Overall, tinkering with a MintDuino taught me quite a lot about Arduinos. Staring at an Arduino for the first time out of a box, it’s a little daunting. There are a ton of little surface mount parts and pins and I had no idea where to start. I had made an LED blink – but that didn’t seem to do much for me.
Having assembled a MintDuino, I already knew what a bunch of the parts already did – so I could focus on building on my knowledge from there. Having the breadboard handy meant it was easy to connect more wires and try out other sketches and configurations. Lastly, I went back over my work from the first time I built the MintDuino and rewired it so that the little red, black and green wires didn’t have any slack. This let me see better which wires when where – which meant I could concentrate on working with the other pins.
I mentioned earlier why I was interested in finding out the absolute minimum amount of parts necessary to operate an Arduino. Well, more on this in the very next post…
I say “start” because my prior experience with Arduinos consisted of just putting shields on Arduinos and uploading sketches. [↩]
I don’t know why they call it a crystal – it just looks like a little bit of metal with two wires sticking out [↩]
I’m just kidding. I’m guessing they’re using a quartz crystal – similar to quartz watches – as a timer/clock. For those of you who aren’t familiar with quartz watches – they keep time by applying a little bit of electricity to a piece of quartz and counting the vibrations of the crystal. [↩]
A few weeks ago I started fiddling with an Arduino in earnest.1 I’ve built things using Arduinos before, but each time all I did was slavishly follow a tutorial as it took me step by step through a process.
Just as a child memorizes the Pledge of Allegiance, committing to memory the right sounds in the right order, I had a grasp of the assembly – but not the underlying meaning. Sure, I built a MakerBot Cupcake CNC (“Bender”), a MakerBot Thing-O-Matic (“Flexo”), an Egg-Bot, a Polargraph/PlotterBot, and an IoT Printer. ((FYI, my MakerBot Replicator 1 is named “HedonismBot“)) However, I have only the dimmest understanding of how the things I did actually created the things I ended up building.
However, I want more – there are several ideas I would like to create using electronics. One is a sonic screwdriver flashlight. Another is device for … shall we say…2 interfering with television infrared codes.3
My goal for this series of posts4 is to document my triumphs and failures playing with an Arduino. I think it’s time to get started on that next post now…
My daughter and I have been working on a project to create paper mache fairies and fairy furniture.1
Photographic Background Stand, ready for shooting!
But first, I can’t help showing off this nifty 3D printable photographic background stand I designed. Inspired by some other designs on Thingiverse, my first draft worked exactly as I was hoping it would. Okay, back to the paper mache.
Printed fairy mold (about 2″ long)
I designed two tiny human-ish figures in OpenSCAD, subtracted them from a block, and sliced the block in half to create a two-piece mold for what we were hoping would be tiny paper mache fairies. I was pretty sure the tiny figures wouldn’t come out well in the printed plastic mold and that the mold wouldn’t work well with the paper mache. However, my daughter really wanted to try to make fairies of this size (about 2″ tall) – so we gave it a shot.
Cast paper mache fairies
I squeezed the paper pulp so it wasn’t sopping wet, added a liberal amount of white glue, packed the printed mold with the mixture, and put a rubber band around it to keep it together. I gave it a few days, then pulled the mold apart. I wasn’t able to add much of the mixture into the upper half, so the reverse side didn’t seem to leave much of an impression. Once it was dry, the dried paper mache stuck to the bottom half of the mold so well it tore in several places as I got it out.
In any case, here are the lessons I’ve learned:
The fairy bodies are somewhat angular – which I think made them difficult to remove from the mold. I would have made them more rounded in the first place, but there were already a lot of spheres and cylinders in the design which were causing some pretty long OpenSCAD render times.
Larger molded objects would probably work better.
The mold would probably release the cast object if I made the interior smoother – either with sanding or acetone.
A release agent would probably help. Maybe petroleum jelly on the inside, perhaps plastic wrap?
I should have sanded the tops of the mold halves – so they would mesh better. This might have allowed the paper mache to be pressed better into the top part of the mold.
It may help to add something to the paper mache mixture to make it stronger. My thought is pieces of frayed yarn or pieces of a cotton ball. This may give it more strength and flexibility.
It’s hard to tell if it would matter, but more glue might have helped.
Very nearly four years ago I had a vision of a totally DIY chess set. In the year 2000 I designed a bag for holding chess pieces – that could be turned inside out and used as a chess board itself. I filled the bag with some cheap1 plastic chess pieces… and then lost it after we moved in 2006.
Fast forward nine years after I made this bag to the year 2009 when I bought my very first 3D printer – my trusty MakerBot Cupcake CNC #465, “Bender.” In preparation for Botacon 0 in the winter of 2010, I was furiously dialing in my printer to create a set of non-black chess pieces so that I could bring a full set of printed chess pieces to New York. I was able to print the pieces – but I still could not find the chess bag.
Today, I found my chess bag – and I’d love to share it with you. I’m not a tailor and I’ve had no formal training with a sewing machine. When I was in college I wanted a very specific kind of carrying bag – so I made it.2 What I know about sewing I learned from my dad when he showed me the basics of the machine operation and turned me loose on my mom’s sewing machine. In any case, I no longer have the designs for this chess bag, but I’m quite sure a clever person, such as yourself gentle reader, would be able to figure out how to put one together from the pictures you shall find within.
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If this is the sort of thing you feel like embarking on building yourself, I have some suggestions:3
Find the fabric first. I’d recommend canvas for the outside, obviously a simple black and white checkered square for the board itself, and a nice pleasant deep color for the border around the checkered board.
Get a cool cord. The bag as designed incorporates a pretty nifty looking shiny cord.
Consider how you’ll put it together carefully. As best as I can recall and piece together from its appearance, this is the rough process I used:
Prepare the checkered fabric. I remember that I had to find a good piece of the checkered pattern that was more square than other parts. I then ironed it so it would hold it’s shape. Then, cut to size, leaving about 1/2″ all the way around the checkered board.
Prepare the cool border. The next step I recall is ironing the cool border, then sewing the checkered square to it. I think my border is about an inch thick – maybe an inch and a half.
Create the bag. I am pretty sure the next thing I did was sewed the border fabric to some of the canvas (but I’m not certain). Once that was done, it looks like I folded the pieces of canvas so that it was trapping the cool red cord, and then I sewed that together. Once I had the two sides individually assembled, I then sewed them with the board-side-out. This had the effect of putting all the seams on the outside edges of the bag, making them visible when the bag was laid out for play. The reason I sewed the bag in this fashion, rather than leaving it so the seams were on the inside of the bag when it was laid out for play, is that it would have caused too much fabric to be inside the bag making it uneven during play.
I simply cannot tell you how happy I am to have united these pieces I printed in 2010 with the bag I made them to be contained within in 2000.
If you and I happen to see one another, and I hope this is soon, please remind me to bring this bag with me and maybe we’ll share a cup of coffee or a beer over a friendly game and a bit of conversation.
One of the best things about modern browsers, the tab, is also the most destructive to my productivity.1 While I wouldn’t want to give up my tabs, I’ve found an awesome productivity hack to help me manage them.
The Problem
In short: cognitive clutter. Visiting Twitter, a favorite blog, or some RSS feeds I’ll end up accumulating tabs in my web browser. These tend to be things I know I may want to come back to later, but wasn’t ready to commit to bookmarking.
The problem with bookmarking a website is that either you have to spend a lot of time curating your bookmarks (into folders or hierarchies or you just bookmark things willy-nilly. What I needed was a way to save things I knew I wasn’t going to visit all the time – but which I might want to see again some day. Since I was pretty sure I didn’t need a bookmark of these tabs, I would just leave them open (I’ll get to them some day and then close the tab).
Those open tabs created what I’m going to term cognitive clutter. Whenever I looked at the top of the browser, all I saw were a line of icons – things I felt like I needed to read or do.2
I’m pretty sure this is exactly why Evernote has a business model – people want to save the things they see or think in a searchable fashion.
The Solution
The answer was e-mail. While I don’t need MORE e-mail, my e-mail is already a repository for information that I want to keep because I may some day need or want to look back on it, but not a place where I went to refer to something all the time.
Now I send myself an e-mail with the subject “bookmarks” and then dump any links I’m not going to get to immediately and don’t warrant a bookmark. To find something that I once saw, all I need to do is search for an e-mail with “bookmarks” in the subject line, from me, and then perhaps a word about the thing I’m trying to remember.
Really, I use this same system for a lot of other things as well. I e-mail myself “todo” lists, “song” lists, and other lists. Things I don’t need to remember, but don’t want to forget forever.
Anyhow, I hope this has been of some use to you. :)
Soaked 3 gallons of shredded paper in 1 gallon of water in a 5 gallon bucket for a week in a warm garage
Each day I stirred the mixture a little – to see if the paper was absorbing the water and disintegrating
We scooped the paper pulp out of the bucket, squeezed the water out, put the pulp into another bucket and added a liberal amount of glue – and then kneaded the glue into the pulp
We then formed the gluey pulp into simple shapes – and left them to dry
After four days, the sculptures (a fairy sized bed, bathtub, table, two chairs, and a footstool) are mostly dried. They all have a grayish brown look with a rough texture – as if they were carved badly from hard rock. It was difficult to mold the gluey paper pulp into shapes – and it didn’t want to keep complex forms. Nonetheless, for their intended purpose – fairy sized furniture and fixtures – I think they look really nice. Once they’re fully dry, we’ll sand and paint them with some acrylic paints (which will also help seal them up).
If they come out well or if there is enough interest, I’ll put together a tutorial on how to do this all yourself. But, in case you’re interested already, the process is pretty simple and there’s not much more than what I’ve described above and in the prior post.
A few days ago I realized that I might have an actual use for all of the shredded paper I’ve accumulated at home and at work.1 Basically, my thought is that I may be able to create a paper mache “clay” by soaking shredded paper in a bucket of water, draining it somewhat, mixing in some white glue (or flour), molding into some interesting form, and letting it dry into a hardened cardboard like form.
Today my daughter and I went out to the hardware store to pick up a bucket2 , masking tape, and a lot of glue. We dumped about three gallons of shredded paper into the bucket, added about a gallon of water, and mixed it up. I plan to let it sit out to let the paper disintegrate a little before we drain it and add some glue.
Just to see if it would work, we packed one of my daughter’s sand toys (a large fish mold) with some of the wet shredded paper and set it out to dry. I have no idea if it will hold together since we didn’t wait for the paper to disintegrate and didn’t add any glue. If it works, great. If not, I figure we can just toss it in the bucket again and let it disintegrate for good.
In the meantime, if you’re interested in learning some really great paper mache techniques, I can’t recommend enough Dan Reeder‘s books on paper and cloth mache. Here are the three Dan Reeder books I own:
Of the three, I think the second (Make Something Ugly) is probably the most comprehensive and interesting. However, the techniques in the others are also really great.
I’ve been working on a few different mechanical projects for a while now. On the one hand, I’m severely limited by my complete and utter lack of mechanical engineering knowledge. On the other hand, I’ve got a 3D printer so I can always arrive at a decent approximation through enough trial and error.
Of course, it’s not like it would kill me to actually learn something about the basics of mechanical engineering. With a bit of googling, I found a page named, “Kinematic Models for Design” which links to a large number of historical texts relating to mechanical engineering – including works from Charles Babbage and Leonardo da Vinci. I found two to be particularly useful – Mechanisms for Intermittent Motion, by John Bickford, 1972, and Five Hundred and Seven Mechanical Movements, by Henry Brown, 1871.
Last, but not least, I want to mention that a friend of mine, Rob Gisebert, told me about the website 507movements.com which is an online repository of the various movements from Brown’s book. Even more interesting, many of these complex movements are are accompanied by animated versions of the drawings in the book.
