DIY electronics, 3D printing and else

Much of the feedback I received on my introductory post revolved around how I didn’t really introduce or explain anything. This was intentional, and for good reason. You see, trying to plan out 5 weeks of cohesive blog posts seemed hard. So I didn’t do it. Besides, if I had explained the idea behind how all my posts fit together up front, then what would this conclusion be? A past tense reiteration of the introduction? Meh to that.
Furthermore, some of the projects used in the blog are still in somewhat active development. Any progress on something could change its importance and position in the overall blog. For example, half my post on 3D design was tentatively going to be about the planned v3 of my arc reactor. It’s going to be 3D printed with channels and grooves for pressing wire and other components into, creating a solder-free pseudo circuit board. You know, if it works. Either way it seemed like a cool potential post, but as predicted, I made no progress on it this quarter. So I’m sure glad I didn’t promise to write about it.

Anyway, now that I’ve justified all that, I’ll explain the loose vision behind my blog that ties it all together. Not counting the introduction, the first post is about the rather large wooden boombox I built in high school, along with some of my complaints on how it could have been better. The main issues are that I didn’t have sufficient manufacturing ability or electronics knowledge to build what I wanted. The next few posts are stories about smaller projects where I learn about 3D printing and solder blinky lights to coffee cans. Post 5, about the MLP BoomBox, serves as the current culmination of my progress since the high school boombox. Alternatively, you could just call it a bunch of stuff that I’ve done and group it together that way.
Although I wasn’t always sure what style I was going for, and it varied wildly between informative and jokes-only, I had fun writing it. Hopefully it wasn’t too bad to read.

 

That’s pretty much it. Our entire organization thanks you for your patronage. The end is NOW!

 

Coming next week: nada! But you can check me out Thingiverse to see more dumb stuff I’ve made. New designs posted occasionally! 

 

ps- It feels weird to make a post without pictures of colorful doodads and whatnot, so here’s one of my current 3d print station!

note: This post was originally titled 5 Years on the Back Burner: Why Your Project Should Replace Pop Culture References with Bluetooth. If you’re looking for that, this is it. We apologize for any confusion.

2011

During my senior year of High School  I built a boombox. It’s huge, heavy, and the exact stretch of ‘portable music player’ I envisioned it to be. However,  due to the costs associated with building a 60 pound boombox , still incomplete. For starters, it needs more buttons, less hanging wires, and a new coat of paint. But the real issue is power. Lead-acid batteries, while somewhat effective, would nearly double the total weight. I actually tried running it off of D-cells as an experiment; they lasted 8 minutes. Lithiums would probably have done it, but were far out of my budget. I realized that even if battery tech improved and prices dropped considerably, I still wouldn’t be able to afford it for many, many years. The only thing to do was shelve the project and wait until I had the means to complete it. 

“But then again,” I thought to myself, “mayhaps this wait could be lessened if the damned thing were more smaller!” Happy with my somewhat eloquent deduction, I started keeping an eye out for suitable parts.

2012

In what was probably 2012 (but possibly 2013 because I don’t really remember) the make-a-smaller-boombox plan made notable progress. I had acquired a decent set of small speakers at a thrift shop, as well as a new smart phone. This is significant because it marked the official retirement of my old clickwheel iPod, and with it, the death of the iPod dock. At least within my personal boombox designs.
Perhaps even more important was the current pop culture. None of the hipster (I think that’s the correct terminology…?) I knew would shut up about Doctor Who, Minecraft or My little Pony. I had a notion to try and harness some of this trendiness for my boomboxes. The plan was to build a few extras, slap a creeper sticker on the side, and try to sell them to cover my costs.

Anyway, one day I’m stranded in a toysRus and run across this thing:

A cheap metal lunchbox, about the right size, featuring perfect MLP graphics. Perfect as in it literally has the music themed horse on it. I believe its name is Skrillex Pony. There was just one problem: the walls of the lunchbox could never withstand the weight of the speakers. It would need some sort of internal structure, with the lunchbox as a wrapper. Of course I had no way to build a perfectly fitted internal structure for this purpose, so on the shelf it went.

February 19th, 2016

Here we are at present day. I now have an adorable 3D printer, and enough DIY electronics experience to probably not catch anything on fire. A pair of 18650 lithium batteries is only 14 dollars on amazon. As proved by my UE Boom, Bluetooth audio can now have passable quality. The My little Pony fad has fizzled out, at least to my knowledge. Maybe I’m just getting old. At any rate, I have tentatively decided to drop the MLP lunchbox from my design, add a bluetooth module, and hope I get this thing built before yet another wave of culture and technology passes me by.

And that possibility is closer than ever! As of 2 weeks ago, I have all the internal components I need. All that’s left is making enough free time to 3D model and print the casing. Easier said than done! As usual, let’s close out with a gallery.

 

In a prior post I described the not at all long or harrowing process of getting my 3D printer up and running. With that out of the way, it’s time to move on to the hard part of owning a 3D printer: Figuring out how to make use of the thing. Having that level of manufacturing potential just sitting around creates a pressure to utilize it. It’s like this nagging feeling that a stopped printer is time wasted. Shouldn’t this thing be constantly churning out organizational and life hack tools that are a brilliant blend of form and function? Yes it should. But coming up with ideas is hard, and sitting around trying to brainstorm inventions is a waste of time. At least for me it is. Trying to notice solvable problems as they annoy you in everyday life is more effective. Once you get that mindset, all your problems are solved! Need a place to store your laptop so you stop almost stepping on it? Just hop on Thingiverse, download some wall mount brackets, and enjoy harnessing that vertical storage space. Smartwatch dock? Spare appliance knob? A weirdly large number of egg holders? No problem. A bracket to hang your bathroom squeegee* from the mirror? Nope. Thanks for nothing, internet.

Designing the Ultimate (aka only) ikea Bathroom Squeegee Mirror Clip

I whipped out the calipers (a must have tool for 3D printing!) and designed this in about fifteen minutes with Sketchup. I was aiming for a very high value to effort ratio, so while I did at least make things symmetrical, it’s not the prettiest design. You may notice the giant triangle cut out in the middle. This is a very lazy way to shave down on material. Proper designers utilize fancy bubble patterns or other fun tricks that reduce material and look appealing, but I guarantee that sort of thing takes at least several minutes longer. 

Take a look at the cut off corners that are highlighted in yellow. Originally those corners were fully intact. When designing this I had only ensured that the squeegee would fit, but did not all account for how much accuracy it takes to guide something into a slot like that. It took an hour and forty minutes to print that piece out, and it was unusable. I saved myself having to reprint by clipping off the corners with wire cutters. This is fine, but the moral of the story is that even after you have the means, and the idea, it can still be hard to execute it well. “Measure twice, cut once.” comes to mind, although “Measure twice, and try not to overlook obvious design problems” might be more appropriate. 

See below for a picture of the real thing, and come back next week for  TBD  5 Years on the Back Burner: Why Your Project Should Replace Pop Culture References with Bluetooth

 

 

*Do you suffer from moderate to severe mirror fog? Get a bathroom squeegee. They make towels look like idiots.

If you were here last week, you might recall that I made the following claim:

“Coming next week: LEDs, Microcontrollers, and How to Build your Halloween Costume in a Cave from a Box of Scraps”

That was a lie. But, regrettably, my replacement article “Box Cats: Putting Cats in Boxes” did not pan out. So today I actually will be talking about some stuff I did for Halloween.

2013

Halloween was fast approaching, and I had no costume or money. But I DID have the following:

• a soldering iron
• kitchen scissors
• a packet of LEDs from some project I never got around to
• wire and connectors
• 1 paper plate
• Folgers coffee 
• one of those clear plastic dummy CDs that comes with packs of blank discs
• 17 different colors of duct tape
• the change in my pocket
• AA batteries

 

Alright! Time to build…(did you catch it?) an Arc Reactor! Since this has apparently become a How-To article (note: It is not), feel free to build your own as you follow along!*

 

Step 1: Brew and drink all of the coffee. This will take a while. Also, we need the lid off the coffee can.

Step 2: Cut the CD down to the size of the coffee lid. If your scissors aren’t working, persist for many hours. 

Step 3: Line the inside of the coffee lid with duct tape

Step 4: Draw a wagon wheel on the paper plate and cut it out. Cut it down to the size of the coffee lid. You may actually want to do this before ruining your scissors cutting up the CD.

Step 5: Solder 3 LEDs together end to end, with a power connector completing the loop. If you do not have wires or connectors, but own a desktop computer, try opening it up. Most of the stuff in there is extraneous, so just take what you need. A small cutting or grinding tool may help with this.

Step 6: Get 2 wires, one for positive and one for negative. Put a connector on one end, and solder the the loose ends to your shiniest pennies. 

 

At this point, you should have something like this:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Did you end up with that? Great! For the last step, tape a bunch of AA batteries together into a pack. Try connecting different numbers of them to your LEDs to adjust for brightness. If the pack gets hot, don’t worry! It will be very cold out on Halloween, and since the pack will be close to your body, this heat will be beneficial.

 

 

 

 

 

 

 

 

2014

It was a month til Halloween 2014. I didn’t have another fun idea for a new costume. But I did have an $25 Amazon gift card. It was time to drop the jokes and various fire hazards. It was time for Arc Reactor v2!

v1 has a number of flaws:

• heavy, bulky battery pack
• no resistors to protect the LEDs (I didn’t know they needed this in 2013)
• the LEDs weren’t the quite the right shade of blue

I ordered myself some new parts to rectify these problems:

• RGB LEDs
• an ATtiny 85 microcontroller
• A 3 volt coin cell battery
• a cheap compact mirror

I already had an Arduino (brand new in the box!) and some old LEDs so I spent a little time with the Arduino blink tutorial https://www.arduino.cc/en/Tutorial/Blink while I waited on shipping. I wanted to blink my LEDs super fast so that they looked on, but with an occasional flutter, for added coolness. This might save on battery, since the LEDs are off some portion of the time, but I don’t know if it’s a meaningful amount. What’s cool is that depending on how you change the delays, you can create either a blinking or dimming effect, or a combination.

After my parts came, I used this guide http://highlowtech.org/?p=1229 to program my ATtiny with my Arduino. If you want to do your own ATtiny project, pay close attention to the pins! The order of all the pinouts change based on whether you’re using them in analog or digital mode.

My LEDs are common anode, meaning the ATtiny is wired to the ground wire of the LEDs. This is called current sinking, because the current is being sunk INTO the microcontroller. This means that in my program, setting a pin to LOW turns the LED on. (common cathodes wired in reverse of this, with power flowing from the microcontroller to the LED).

I also added a red mode, with a power button to switch between them. Here’s some picks of v2, and a link to the code if you want details.

https://drive.google.com/file/d/0B7eJ8-sLX8UCTl9taFhQS0dvZU0/view?usp=sharing

 

 

 

 

 

 

 

 

 

 

 

 

 

*Do not do this. This article is for entertainment purposes only.

If you are at all familiar with 3D printing, chances are you’ve heard of the MakerBot Replicator. It’s a $3000 beast featuring industry leading print quality and ease of use.

“But I’ve already heard about the Replicator! In fact, I know so much that reading about it would be boring!” Well then great news, hypothetical reader, for this is a DIY blog, and we shan’t be mentioning it again.

 

Instead, we’ll be discussing this:

The pile of assorted junk on my table the is in fact the Printrbot 1405, Simple Maker’s Edition. Weighing in at £245, or $350 dollars, it’s an affordable option if you want to get started in 3D printing and have lots of time on your hands. Lots and lots of time.
Today I’ll be detailing my quest to get high quality prints out of this little pile of scraps. The assembly process wasn’t particularly interesting, so here’s a stock photo of the finished product.

The First Print

See that shiny metal plate in the photo? That is the build plate, and it is made of aluminum with a smooth shimmering finish. What happens when you try to lay hot plastic onto this? The plastic doesn’t stick. And how important is that to 3D printing? A lot, apparently. I do not know why this is not mentioned in the build instructions or accounted for in the design process, but the solution is blue painters tape.

By the time of the right hand photo, I had calibrated my printer fairly well. These are all software adjustments. You tell the printer to move to a position or distance, and check if a 1 mm movement command translates to 1 mm movement in the real world. You have to do this for the the X, Y and Z axis, as well as on the filament feed. This ensures that plastic ends up in the right location, in the correct amount. If the printer thinks it is feeding in 10 mm of plastic, but instead gets 15, you end up with big globs of plastic dripping everywhere.

 

 

 

 

 

 

Z-wobble woes

Show of hands, what do you think would be more precise: a belt or a precision machined threaded rods? Personally, I’m inclined to bet against belts. Belts are for pants.  

 

Anyway, even after all my calibration, I still had weird imperfections in my prints. My sidewalls had weird ripples in them. I assumed they were caused by some sort of slop while the printer moved back and forth along the XY axis. So I tightened the belts. And then I tightened some more. And then I snapped one of the parts the belt was connected to. Did I mention how this thing is mostly made of wood?

Tightening the belts had no real impact. After some online research, I learn that this is called “z-wobble”, and is caused by imperfections in threaded rod. Common factors are how straight the rod is, and how it contacts the motor shaft that rotates it.

Upon inspection my threaded rod is obviously bowed. I drew up a new part to hold it straight, waited 3 hours for it to print, and did a test run. Results were negligible.

Fortunately, I later hit the wrong button while setting up a new print and crashed the whole Z carriage (meaning the whole top half of the printer) down into the print bed. I frantically switched off the power, but the motor had ground it down so tightly that I couldn’t easily release it. Since it seemed like the least damaging way to take the tension off, I disconnected the z-coupler. After putting it all back together, I now had nary a hint of z-wobble, and great looking prints. I had no idea why, nor how to replicate it. This was fine for about 6 months, until I had to make a repair that involved disconnecting the coupler again. Just as I feared, I was back to annoying z-wobble afterwards.

So what was the cause? Essentially just luck. Below is the diagram for how the coupler is supposed to be installed.

 

Despite what the diagram might lead you to believe, the best option is

number 2. But that on its own is not enough. What you need to have is the threaded rod rotated to the perfect spot relative to the motor shaft. After the print bed crash fiasco, I had accidentally achieved this.

So, for the happy ending, Yes- as of a few weeks ago I finally managed to replicate my initial success. The key was disconnecting the coupler, moving it just slightly, and trying a test print. About forty times.

Coming next week: LEDs, Microcontrollers, and How to Build your Halloween Costume in a Cave from a Box of Scraps

 

 

ps- this post is titled “whirrrrrrrrrr vwom vwom vwom” because of this:

All images are my own unless otherwise stated

Back in 2011, for reasons I can no longer recall, I decided to build a boombox. Here are some 3D mockups:

 

Even at this early stage in the design process I already had to start making compromises. The original plan called for an amplifier much more powerful than a car receiver, but after drawing my model I knew there was positively no way anything else would fit. Especially not in addition to a battery and power supply.

Changing to a car receiver created new design constraints and consequences. My old design was a basic 2 channel (Left/Right only) stereo, but car receivers are predominately a 4 channel (Left/Right and Front/Rear) affair. After some research I learned that connecting two channels to a single speaker will burn up most amplifiers, rather than double the output sent to the speaker. So it was either waste half my power or change to a 4 speaker design. Conveniently, my Dad had a pretty nice set of Infinity car speakers gathering dust in the garage (he had somewhat recently gotten a new car and wasn’t interested in tearing apart all the door panels), so I didn’t have to work that change into my budget.

Next I needed to pick out a receiver. Still aiming for a powerful system, I settled on the Kenwood KDC-X791. It’s capable of delivering a sustained 22 watts per channel, significantly better than the cheaper 15-17 watt commonly seen at Best Buy. It also has a large array of inputs and outputs, which is nice. I laid all my bare components out on a table and power them up.

I gathered from my research that a speaker enclosure was just as important as the speaker itself, but only then did I realize how much of a difference it actually makes. Removing a speaker from its enclosure essentially makes it no better than one of those singing greeting cards. I exaggerate but it’s really quite significant.

Designing a speaker enclosure can turn into a very complex engineering problem if you let it. Is the internal volume correct for your speaker? Did you get this volume with the correct ratio of width, length and depth? Is your material dense enough? Did you port your speakers to try and increase the bass? Then you better start from scratch because that changes everything. Or at least unreliable online sources say it does. After much time getting nowhere I reduced my considerations to 1, some random enclosure volume calculator I found online, and 2, the largest piece of plywood I had.

At this point I had recovered from the initial setbacks entailed with a near total redesign. Except I still had to build the thing. With zero woodworking experience. This resulted in many hours of me just sort of staring at sketches, hoping to be hit by inspiration on how to proceed. I don’t remember all the details, but the main difficulties were as follows:

• Finding ways to clamp or apply pressure to the the glue joints on something so large.
• Running the bench saw. I didn’t have much spare wood, and the stress over whether or not I was 100% sure I was cutting on the right side of the line. Having parts a saw blades width off is not fun.
• The bench saw again, but this time getting angles to fit.
• Wood is imperfect and bows and bends and cracks and splinters and other terrible things
• This thing weighs around 60 pounds and became hard to maneuver toward the end

If you want more details here are some photos:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

My boombox was a reasonable success, but there was a lot I was unable to achieve. It doesn’t have a handle. It doesn’t have a rechargeable battery, and it doesn’t have the paint finish I would like it to have. But these are mainly just small matters of money (5 more years and maybe the batteries will be affordable!).

I was happy with what I accomplished, but ultimately disappointed with the lack of blinking lights and that I had to use a car receiver. What I really wanted was a much more DIY approach. Custom lights, custom buttons, no silly commercial devices. But I lacked the electronics knowledge to create such a thing. Not to mention the construction limitations imposed by limited woodworking skill. What I truly needed was to vastly improve my manufacturing capabilities. But how could I possibly do that? It was time to shelve the project and give up.

 

 

Coming next week: What to Expect When Your 3D-Printer is Made of Zip Ties and Wood