Android Blue or iOS Purple? Update on the OOMA project

The Object Of My Affection Lamp   I thought I would jump in and blog on my current progress at the Makerspace with a lamp called OOMA, or The Object Of My Affection. It’s a lamp that is shaped like a GPS Navigation pin that rotates to always points toward the one you love… as long as they allow you access to their Google Latitude account :). I am finalizing hardware designs and now moving into writing the software and how it talks to the Internet.

Initially I would have waived it off as using WiFi, or Ethernet, but work on another project (Marco) has illuminated several obstacles over multiple use cases (configuring Wi-Fi, closed networks, IP addresses); instead I think the approach will be to opt over USB (via Arduino Leonardo). I figure, if people will load up a coffee cup heater or foam missile launcher to USB, than there is no issue with port scarcity.

It’s not a lamp without light, and at some point OOMA will light up in either Android Blue, or iPhone Purple. Lighting the lamp will, however, have to relegated to a v.2 build, due to some complexity in the diffusion of light in such a cramped space. Additionally, I’d like to investigate EL panels to light it up.

Finally, I am coming up on the decision to be a DIY offering, or to design it to be marketable - do I build as a one off and just offer the blueprints to others or build an end-to-end consumer solution complete with potentially an NFC tag to tap and pair a user and their lamp.

MegaMax 3D Printer

MegaMax 3D Printer

MegaMax 3D printer based on MendelMax but bigger and minus plastic parts.

This is my on-going project at the Milwaukee Makerspace.  It is a 3D extruded plastic printer with about 1 cuft build envelope.  I want to print life-size human skulls (among other things) from CT scan data.  The printer is made mostly from salvaged parts and materials so the cost has been very low.  When it’s finished it will have a heated 12″x12″ bed (13″x13″ if I can find an aluminum plate that big) and dual extruder so it can print in two colors.

I have learned a lot on this project- some things that work and others that don’t work so well, and how to use a milling machine to drill holes precisely and square the ends of the 8020 extrusion pieces used to build up the frame of the machine.

I could not have done any of this without access to the people, materials, and tools at Milwaukee Makerspace.  Every time I go there to do some work on this project someone says something that gives me new ideas for improvements to the design.   I frequently find materials and parts left for me on the machine’s cart by other members who know what I’m trying to do.  If you have a project idea find your local Makerspace and get busy- there is nothing that will get your creative juices flowing like being around a bunch of people with similar interests and different skills and experience!

MMS Eclipse watching party

Although poorly attended (only one full and one future member) everyone had a great time observing the 98% solar Eclipse.

Using the official MMS pinhole card:





Too bad the eclipse image is so poor, what a minute – whats that on the building next door?


Openings between the leaves of trees are acting as pin hole cameras and giving hundreds of images of the eclipse, we felt a little silly looking at the tiny ones the card was making for the first half hour :-)

You can also see some on the leaf in the foreground (I’m writing this on an old netbook so I can’t tell how the pictures are coming out, so I didn’t clip or tweak them)

And just so you don’t think its some other effect, here’s a shot at the max we witnessed, notice the arc is at the top instead of the side:

I’m still not sure why we had such a poor turnout, after all its only a 36 hour drive to San Francisco!



Makers, assemble!

Yeah.  Having access to a laser cutter is pretty boss.  I’m planning to wear this to the premiere of a certain movie this weekend.  Four layers of acrylic; two diffuse, two opaque.  11 LEDs, 11 100 Ohm resistors, some phone cord, some solder, and a 9V battery.  There’s no lack of great pages on Instructables about how to make your own.

Toddler Swing from a 5-Gallon Bucket!

So how exactly DO you make an 18-month-old girl happy? Well, it doesn’t take any money or a trip to Wal-Mart. In fact, some rope and an old 5-gallon bucket are more than enough for a fun springtime afternoon!

Last weekend, my wife, young daughter and I went over to my parent’s house. My Dad had recently been over to the store to get chicken wire for the next chicken coop he’s working on, and looked at some playground equipment while there. (They have EVERYTHING at the farm store!) He mentioned how the toddler swing-set they had seemed “too-safe”. That is that it was all blow-molded plastic, had straps and safety belts in all directions, and looked like it would take longer to get the child in and out of the swing then she would actually spend playing in it!

It seemed like it would be simpler just to build something ourselves. We had a 5-gallon bucket and some rope, along with a drill and a jig-saw. Thus, the 5-GALLON BUCKET SWING was born!

Construction was pretty simple. We just pulled off the bucket handle, and then cut two “mouse-holes” for the legs in the front of the bucket. Matching cut-outs were made in the BOTTOM of the bucket, because toddlers legs are so short. We cut down the total height of the bucket, and made it swoop very low in front, high on the two sides, low again, and then high for a back-rest. Four holes were drilled (3/4″) to pass the rope through. Rope goes down from the top, loops through the holes, then back up and out the other side. That way, we only needed one piece of rope, instead of two, and it makes it a little easier to adjust for height.

We didn’t even have a good tree to hang the swing on, but there were two great pines (which provide shade.) We ran a length of sturdy steel pipe between the trees as a cross-member to hang the swing from. Once tied in place, the swing was ready to go.

She swung on it for nearly an hour and a half – this from a little girl who usually spends no more than ten minutes on the swing at the public park. Unfortunately, I didn’t have my camera with me, nor could I really document building the swing, as we were making it up as we went. However, my brother had his cell-phone camera with and grabbed a pair of photos of the first use of the swing.

Being made from plastic, the bucket swing is weather resistant and should last a long time. It wasn’t made in China. It didn’t have any packaging, and it was plenty of fun to make and use. Not bad for a weekend afternoon.

But what’s that? YOU want to make your own 5-gallon bucket swing? Sounds great! Go for it. Here’s some general directions for you.

First, get a bucket. You probably already have one around, but if not, you can buy one at the home improvement store. Better yet, just ask for one at your favorite local restaurant. Pickles and all sorts of industrial-sized food goods often come in 5-gallon buckets.

Next, remove the handle.

You don’t HAVE to take it off, but it will just get in your way otherwise while you are working on the project. Look where the handle connects to the bucket and you will be able to see which way you have to bend the handle to be able to just pull it out by hand.

Next step is to cut a pair of “mouse-holes” for the child’s legs. In these photos, I’m using a black marker to show where I’ll being cutting. When you do this, either cut around the OUTSIDE of your black markings, so there’s no marks done on your finished swing, or just eye-ball it. The leg holes are cut in both the front AND the bottom of the bucket, so the child’s thighs sit on the bottom of the bucket, but from the knee on down hangs straight downward through the bucket.

You can cut the bucket with almost anything, a handsaw, a Dremel tool, a jigsaw, or reciprocating saw. I think a jigsaw is the easiest and most straight-forward for this.

Try to make all the cuts on the project nice swooping curves. Once all the cuts are made, you can sand the edges as well.

Next thing to do is mark the lines for the main cut. Essentially, you are cutting really low across the front, above the leg holes, and then high on either side, near where the bucket handle originally connect, swoop low again for where the kid’s armpits are going to be, and high on the back for a back-rest. That may sound complicated, but a couple pictures are worth a few thousand words.

You’ll also need to drill four holes. Two are the main “hanging holes” which will be located directly below the original bailing handle connection points. The other two are roughly below where the child’s armpits will be, and allow for the rope to go through to the back of the swing, around the outside of the bucket. That way, the rope acts as part of the back-rest, and prevents backward tipping, but is not between the child and the back-rest. You probably want to drill the holes BEFORE cutting the bucket in half, as it will have more strength and is easier to handle in its original bucket form.

Once those holes are drilled, cut that swooping line to make the bucket into two halves.

Frankly, I’m not sure what to do with the top half of the bucket that got cut off. If you have a good idea of how to make use of this “waste”, please let me know!

By now, the bottom half of the bucket should be starting to look like something you might see at the park.

Next, get yourself some rope that’s at least twice as long from your favorite tree-branch to the ground. Thread one end of the rope DOWN through the outside of one of the ears, out through the next hole, around the outside of the back-rest, back IN the next hole, the up and out the other ear. Again, it makes more sense if you look at the photos.

Also, please note that on this particular bucket swing, the back-rest is a little low. It should really come up nearly as tall as the side ears. When we worked on the first one at my Dad’s the little girl was right there. She cooperated well in that she was happy to sit in the bucket while we marked the positions and distances of the various parts of the swing. (The little girl was not around while I was working on this particular bucket. I highly suggest using your toddler as a template for your project!)

Next, you just have to hang it. Tie one end of the rope to the tree branch. Make sure the swing is facing the direction you would like it to face. Slide the swing on the rope until it is at the height you would like it to be at. That’s usually between the height of an adult’s waist and knee – a good pushing height once the swing is drawn back.

Most likely, you will want to use an outdoor-rated, UV-resistant, artificial fiber rope. Otherwise, you could also chain or cable, but rope is simple, easy to work with, and doesn’t pinch little fingers.

The proof is in the pudding. After checking that the swing is tied securely, at the right height and level, put your little darling in there and give him or her a push!

If all has gone well, you have a smiling child swinging away on your aren’t-you-proud-you-made-it-yourself swing-set!

Once the tot is in there, you might want to confirm that the leg holes are the right size, and that there’s no chafing or rubbing. In the photo above, it looks like the left leg hole (her right leg) could be a little bigger.

If you, like me, enjoy irony, you might want to design your bucket so that it keeps the “THIS IS NOT A TOY” warning on the side.

Here’s a couple of views of the back. In these photos her shirt is covering part of the back-rest, but it’s still a little low. In the next bucket swing, I am going to make sure the back-rest is higher, nearly as tall as the side ears. Make sure that there are still the downward swoops for the armpit area. This allows the child to have comfortable arm position, NOT rubbing on the bucket, and still easily reaching up to grab the rope.

That’s about it! It’s a simple project, inexpensive, fun to make, and fun for the kids to use!

Here’s a video quickly showing all the steps as well!

Do you have any ideas for improving this design? Have you made one? Let me know! Leave a comment or post a photo!

One last treat for you – I created a one-page PDF file for you that has step-by-step directions for how to build the swing. Click the link , then print out the file and take it to your workshop with you!

Lastly, HAVE FUN!

DIY Slide Scanner

DIY Slide Scanner

I have a confession to make: I’m about 80% done with my own device to photograph slides and convert them to digital form. I’m pretty sure I will abandon all of my efforts and attempt to replicate this DIY Slide Scanner I saw from the Metrix Create:Space folks.

And yeah, I’ve already got a working slide projector. It may be the same model you see in the photo above. (I picked it up at a WCTC auction for $5.00 years ago.) I’ve already got code to trigger my Nikon via an IR LED, so the main thing I need to do is wire up the remote to advanced the slides, and fit it all together. I’ll probably just build a wooden platform to hold it all.

And then it’ll be time to… DIGITIZE ALL THE SLIDES!

Unexpected Detour

When I arrived at the space Sunday, I had planned to work on a circuit board design in DipTrace.  After I left, I had spent six hours rewiring a golf cart.  Allow me to explain…

It all started when I went to take the trash out.  I used the golf cart with the flatbed to ferry the cans out to the dumpster.  After emptying the cans, I rode back and decided to charge the cart’s batteries.  Tom and Rich had just returned from lunch and Tom suggested we swap out batteries instead.  While swapping them out, we decided to also rewire them.  While rewiring them, part of the cart broke.  There’s a small white plate under the driver’s seat.  It’s about 4″ x 6″, likely made of asbestos, and holds a series of copper contacts that a lever attached to the gas pedal slides over to select the speed of the cart.  And it broke in two when we tried to tighten fix a wire on it.

We had a few options: try to mend the old, brittle plate, replace it with something new, rewire the whole thing, or scrap everything out for a solid state motor controller.  Not wanting to adopt a new project or sacrifice a motor controller that could be better used elsewhere, I volunteered to try and fabricate a replacement for the broken part.

First I documented everything just the way it was.  I labeled wires, took photos, scribbled down notes, etc.  Next I went about removing the broken plate.  There was probably more rust than metal on those bolts.  Then I took a pair of digital calipers and a ruler and measured the locations and sizes of holes for each component.  I considered using the CNC router or drilling a plate by hand, but the laser cutter seemed to be a much faster and precise approach.  I drew up my replacement plate in CorelDraw and found a scrap of 1/4″ acrylic that matched the size and thickness of the old plate.  After some tinkering with the printer driver and a dozen passes with the laser, I had a copy of the original in plastic form.

The next few hours were spent migrating the old parts over to the new one and wiring it back in.  Right around 7:00 PM, I tied some batteries together and the thing leaped forward.  A few more tests and it should be as good as new.  Someone suggested that maybe the plate was asbestos to avoid heating issues so we’ll keep an eye on that too.

My neverending quest for quick turnaround prototype PCBs

For years I have dreamed of a fast way to prototype PCB for projects I am designing.

20 years ago I was using rub on drafting tape and stencils – slow and spotty results.

I tried to modify a plotter to plot resist directly to a PCB – no luck.

Magic markers – I’m no artist.

5 years ago I hacked a laminate router by tapping into the stepper controllers and adding a better Z axis – It can rout boards ok, but takes some tweaking.  It only does fairly wide traces.  But its great at drilling holes!

2 years ago I tried the inkjet printing systems – lots of smeared wet ink and poor registration, not very effective.

I opened up a laser printer and tried to get a board to go through it – almost worked, but the fuser was to narrow to take the board.

Although I haven’t found a fast system yet, I get by with the PNP Blue material and a good laminator.  Although I am regularly disappointed when dust, not quite clean boards, minor wrinkles and other issues leave gaps in traces that need touching up.

Which brings us to the latest attempt:

Now that the maker space has a small laser cutter I am trying to find something I can coat a board with and either burn away or melt onto the board to act as an etch resist.

Early attempts with paint had moderate results – our laser cutters on only 25W so it didn’t burn it cleanly.  I have heard that using flat black paint and a more powerful laser works.

Paste wax and markup fluid weren’t dark enough for the laser to vaporize (thinking of trying black crayons)

The latest attempt uses laser printer toner (just like the PNP only skipping the printing and iron on steps.)

The problem is how to get an even coat on a board without it blowing around.  Static electricity has potential (just like what they do inside a laser printer) but I don’t like the idea of a 5KV power supply exposed and handling powered toner is an automatic mess.

So for the first attempt I mixed the toner with rubbing alcohol (30% water).

Messy stuff!

I painted it on with the tongue depressor but it seemed to coat evenly and took only a few minutes to dry:

It mixes well and paints on fairly easily, here are some sample prints I did at various power and speed settings.  I cleaned the board fairly aggressively with paper towel and rubbing alcohol.

None are quite clean enough to become PCBs but they are getting close.

Although the toner paint looked dry, it may still have had some water in it.  I plan on trying a batch with denatured alcohol (100% – no water) and see if it works better.



Updated progress

I have been trying a number of materials and methods to make my fast turn circuit boards.

I’ve decided that last toner is too messy and there are too many variables to create a repeatable process.  So now I’m trying various other masking materials:


Black and white spray paint – it works ok, but the ash left behind by the laser resists the etchant and leaves you with a poor etch.

I also tried tape:  Painters tape, electrical tape, clear and brown box tape.  The masking tape worked ok until the etch was slow and the tape started to dissolve.

I held a few of the boards up to the light so you can see how it etched:







One of the other members of the space found someone who had made the black paint work.  The process is to do 2 passes with the laser – the first burns off the paint, the second burns off the ash!  Then you wipe the board down with rubbing alcohol to clean off any residue.   Here is a set of 3 projects I lasered and etched at once:

This board turned out rather well, I had some trouble with the etchant taking for ever so lost some of the detail on the lettering, but the boards came out nicely.  I should get even better results on the next project.

In an attempt to speed the entire process up I tried to drill holes with the laser cutter from the back of the board:

   Not very good results!  After about 6 passes it still didn’t cut through thin PCB material and stunk and smoked the whole time!







So instead, I used the laser to cut wholes in a small piece of acrylic to use as drill guide:




This gives you a pattern to follow using a Dremel and the holes wind up in the right places and nicely lined up.  I drilled 2 holes in opposite corners of the board and used the leads from resistor to line up the template and board and hold them together while drilling.




This image shows the template attached to the board and about half the holes drilled.  This worked very nicely!  The only problems was small disks of acrylic getting stuck to the drill bit (you can see little craters on the left side of the board where these came from)  I had to clean the drill bit twice to drill the whole thing.  Either bigger holes or a different plastic might fix this.


This is first of the 3 boards I put together and it works just fine.  It is a level translator for the encoder you see in the holder.  The encoder will be attached to the drive motor in my electric car and feed back motor position to the controller.  The encoder is 5V and the controller wants a 15V signal.  The test bed uses a 15V power supply and LEDs on the 4 quaderature outputs.

Encoder test video

PWM Disco Ball


At home, I have a small LED light that is designed for use under cabinets. I use it mostly to illuminate one side of my aquarium, and I occasionally pull it out to use it as a light for filming video.

The problem is that it is quite a bit brighter than the other LED light I have on my aquarium, and for video use, it would be nice to be able to adjust the brightness of the light as well.

However, LEDs just CAN NOT be dimmed with a regular old light switch dimmer the way an incandescent bulb can. I had heard that they can be dimmed through PWM – pulse width modulation. I was already familiar with the term, as that’s the same technique used to control the speed on the motor of my homebuilt electric car.

So, when I was in at the MILWAUKEE MAKERSPACE I asked Tom G if he had any suggestions for me to start learning electronics by building a simple PWM dimmer for my fish tank LED light. As a hobby, he has built a fair number of robots, and pointed me to the Dallas Personal Robotics Group web page, where they had a number of tutorials posted. Sure enough, they had atutorial on building a simple motor speed controller, using a 555 timer chip. It also included a very nice explanation of Pulse Width Modulation. It’s really a simple thing that is sometimes hard to describe. I don’t think I have ever heard it explained so clearly as in the DPRG tutorial.

Part of the fun of the Milwaukee Makerspace is just having lots of odds and ends around handy, instead of having to take a trip out to the hardware store or electronics warehouse. A 555 timer, a few resistors and capacitors, and a bread-board were I all right there, ready for me to prototype this simple circuit. Even with nearly no electronics experience, it was pretty easy for me to follow the tutorial and connect up the 555 and other components into a working circuit.

After some playing around with it, I found that this circuit could not only control the speed of a DC motor, or dim an LED light, but somebody else suggested I hook a speaker up to it. Sure enough, I could generate various frequencies of sound as well! (Although since it’s a square-wave, none of them sounded very nice!)

So, the next time I was going past Radio Shack, I stopped in and picked up some “Perf-Board”. It’s sort of the step between a breadboard and a custom circuit board – just a board with a bunch of holes in it, all evenly spaced, ready for you to insert electronic components and solder them together.

I then recreated my original breadboarded circuit on the perf-board and soldered it all together.

I also grabbed a used plastic case from the Makerspace parts pile to use as an enclosure for the circuit-board. A bit more scrounging meant that I had a power connector for it that matched the power supply for the LED light. I’d be able to use the same power supply whether I was using the LED with or without the dimmer.

A bit more soldering (only ONE soldering iron burn!) and installing the board in it’s case, and I now officially had a PWM Light Dimmer for my aquarium!

But here’s where it gets more interesting. I really built this not so much out of need for a dimmer, but as a learning experience to find out where theory and practice come crashing together in the real world. After assembly, I already noticed a few ways to improve the final version of the device. (I’m still thinking of this as a proto-type or first run!)

Ideas for future improvements include:
1) A power indicator light. If the PWM is turned all the way down, it’s hard to tell if the device plugged into the dimmer is even on or not.
2) A volt-meter display. It’s pretty neat to be able to see that the perceived output voltage of the dimmer is. I have several 12V devices that I would like to run from a large 14.4V battery. With a volt-meter built in, I could set the dimmer to send exactly the correct output.
3) Battery Operation. The surplus case that I used as an enclosure already has a removable cover. It shouldn’t be tough to fit some AA batteries in there to make the whole thing run without requiring a power cord to the wall.

Recently, we through a birthday party for a friend of ours. She requested a Disco Ball at the party. My sister found a disco ball at the clearance table at a store, but no matching disco ball motor.

Aha! Here’s my chance to not only save a few bucks by not PURCHASING one, but also learn about motors and gear reduction! Next time I was in at the Makerspace, I dug through the bin of scrap motors on the “Hack Rack”. An AC motor? No that’s no good, it has to run on batteries.. Stepper motor? I have no idea how to run one of those…. Hmmm. What’s this? I eventually found not one, but two motors, both connected to to some gearing and a pair of tiny square drive axles. The motors were marked as 24V DC, and I knew that if I drove them at a lower voltage, they would still work, but not spin as fast. I tested them both with a benchtop power supply and saw that they worked. The one was geared to a much faster speed than the other.

I later tried running both directly from a 9V battery, as it is the simplest power supply I could think of. The one motor, through the gear reduction, would spin the driveshaft at exactly 2 revolutions per minute at nine volts. That’s almost PERFECT disco ball rotation speed!

I bent a paper clip through a connector on the end of the drive shaft to hold the ball, and added a carbineer to hold the motor to the ceiling. POW – top-notch disco ball rotation!

For the party, I let it run on just the 9V battery. It got left on overnight, and was still running the next afternoon. What a nice, efficient motor!

But what if I wanted to spin that ball a bit faster or slower? Either motor was designed to run up to 24 volts. My PWM “dimmer” was really a motor controller anyways after all. That was all set up for 12V. I connected the dimmer to the more quickly geared motor, hung it up, and strung the disco ball from it. Sure enough, by varying the potentiometer on the dimmer, I could make the ball spin from way too slow to nausea-inducing quick!

I even noticed that at very slow speeds, the motor made a little bit of a high-pitched whine. Remember how I said an audio speaker could be hooked up to generate a tone? At slow speeds, the pulses of the motor controller can actually be heard – the frequency is within the range of human hearing. The first time I ever heard a Chevy Volt, I noticed that it made a quiet, yet distinct noise right as it accelerated away from a dead stop. That’s the sound of the car’s electric motor controller picking up frequency as the car increases speed.

So there you have it. From dimming a light, to spinning a ball, to driving an electric car, Pulse Width Modulation is a simple, yet useful, trick that’s all around us. If you would like to build your own basic light dimmer/motor controller, check out the info at:

But why stop there? Once you have some mad soldering skills, what’s to stop you from building a bigger version of a motor controller, maybe something that can push a full size car around? Check out the Open Revolt controller – a motor controller anyone is welcome to build!

If you are anything like me, you like to learn new things, and find it fascinating how various areas of industry and science are all related. It’s far more fun to build and design something yourself then it is to just purchase somebody else’s.


Laser Cutter Venting System Progress

The laser cutter is now connected to the new vacuum pump!  I’d still like to do some endurance testing on it to fully put it through it’s paces, and we need to finish the last leg of the vent pipes up in the loft, but otherwise you can use it to cut wood and such just as you did before.  I wouldn’t suggest cutting any plastic just yet as the vent pipe is just discharging over the hallway by the bathrooms.  There’s an instruction sheet on how to turn the vacuum pump on and off taped to the machine and my contact number if you run into problems.

You can see pictures here: