Fail

One of the rites of passage for the Power Racing Series is to use the cheap Harbor Freight wheels on your car. When you can get the whole thing, tire on a rim with a hub and bearings, it’s quite appealing. Also, the tires can be as cheap as $5.00, and that’s before you use a coupon. (I should mention the bearings are crap, and those should probably be replace. Still, you can easily start with them!)

In case you can’t tell from the photo above, they are sort of terrible. Cartastrophe used them their first race and got to experience what it’s like when your car goes one direction and your wheel goes another direction. This is a (somewhat) common occurrence, and it’s always hilarious (when it happens to someone else.)

Harbor Fright!

But! Hacker and Makers and Those Who Scrounge and are Cheap often enjoy the challenge of modifying things to do what they were not supposed to do. Like making wagon wheels handle the lateral forces of sharp turns at 20 miles per hour.

Over the years team have added in gussets, reinforced the rims with steel plates that have been drilled out for the axle and bolts, some teams have 3D printed pieces to strengthen the rims (which actually worked!) and at least one person mentioned how they use a piece of “laser cut steel” and I’m like… wut? Yeah, hackers…

So there are options, and there are always options. I mean, check out the crazy hub story from Tom at Milwaukee Makerspace!

A Better Rim Job

While thinking about an easy and cheap way to strengthen the rims I was wandering around the hardware store and found the flange you see above, which was less than $4.00. Now, it doesn’t quite fit properly. I mean, I’ll need a larger hole for the axle. With a 1″ axle I’m hoping a 1″ pipe flange hole will work, though we may have to file down or drill out the threads. The bolt holes do not match, but drilling out the holes on the rim might be the solution to that, and maybe switching to 1/4″-20 bolts…

There are also PVC flanges that may work. Those might prove easier to drill out, though the iron flanges are still less than $5.00 and can be found locally.

If you’ve got an idea how to easily and cheaply use a COTS part to solve this problem, let us know! It should require minimal modifications, hopefully just drilling and filing, and not involve laser cut steel. ;)

Claw Machine

Dr. Prodoehl was telling me about a colleague of hers that collects animal parts, and mentioned a claw from a pheasant, and I (sort of jokingly) said “Hey, I want a pheasant claw!” and then forgot about it until she brought one home for me! She also brought home a baculum, which is a raccoon penis bone, and while I haven’t found a use for that (yet) I did manage to use the pheasant claw. Obviously I built a Claw Machine.

Claw Machine

I often find weird little motors at Milwaukee Makerspace and keep them around for projects. This one had a strange gearbox and spring and belt. It also had some weird angles which made it difficult to mount, so I 3D printed a mount that worked well enough with it that I could screw it down into a piece of wood. There might also be some hot glue involved.

Claw Machine

I also ended up 3D printing a gear and some arms. Those are the sorts of parts that it makes a lot of sense to laser cut, but I wasn’t around a laser cutter at the time, so I just 3D printed them. I really do enjoy digital fabrication…

Claw Machine

There’s a few extra holes in the wood because I seemed to have a hard time finding the right position for the pivot point of the arm. I managed to find one that worked and left all the previous holes as a reminder than you don’t always get things right the first time. There’s also an abundance of nuts on bolts, because spacing is an issue best solved with washers, or nuts, or whatever is lying around.

Claw Machine

Speaking of first times, besides wood, I tend to not include natural materials (like, animal parts) into the things I make, so that was interesting. I attached the claw with the simplest of methods… zip ties. Also, this is called “Claw Machine Version 1″ because I intend(ed) to make some improvements, but I might never follow through with that idea.

Claw Machine

The claw is really interesting to look at. Is this piece some sort of cyborgian statement about the future where animals and machines are combined into some sort of terrifying nightmare? Probably not.

Claw Machine

claw-machine-6323

Claw Machine

PCB

Hey, it’s only been six months since my last post about motor controllers and the Power Racing Series so I guess it’s time for an update! If you missed it, I’m working on a tiny electric vehicle that can serve as a reference for teams of beginners to build their own.

Controller

In the last post I talked about a cheap motor controller that required an expensive throttle and alluded to a method of using a cheaper throttle… here is that method.

I started by asking questions on the Power Racing Series Google Group, and people much smarter than myself offered advice, and that’s where I learned about digital potentiometers. I ended up testing my idea with help from this tutorial and eventually got an MCP4131-104E/P-ND digital potentiometer (for less than $1.00) and paired it with an Arduino Nano that was less than $2.50 to create a converter that allows a cheap throttle to be used with a cheap controller.

If at any point you feel like saying “Hey dummy! You should have done it this way!” feel free to leave a comment. Most of my crazy pursuits involve me learning a lot along the way, and this is no exception, so I’ll keep going.

Controller

After I had a working prototype on a protoboard I decided to design a PCB because I’ve been working on getting better at PCB design for the last two years now, and it’s sort of fun (and challenging!) This is the most complex board I’ve worked on so far, and of course, mistake were made…

First of all, see those wires coming off the board? There should be screw terminals there, but I was unaware that the holes were the wrong size and the pins of the screw terminals did not fit. Argh… wires will do for now.

Controller

Everything wired up and ready to go! Except, it didn’t go… Seems I managed to not quite route everything the right way. Back to the drawing, and tracing all the connections with a meter, and I discovered a connection that shouldn’t be there…

Controller

…but that’s what Dremels are for! I was able to cut the trace and get it working. Back to the computer to make a few changes to the PCB. (And yes, I am still using Fritzing. I’ve gotten used to it, and know how it works, so… okay then.)

Controller

A few weeks later I got a new version from our friends at OSH Park and this one fixed the issues and worked! I should still get similar screw terminals but hey, it does what it should do, so that’s something.

You might notice some of the analog pins and some ground connections broken out at the front edge of the board. There are for future enhancements. It would be fairly easy to add in “cruise control” (for parades) or a speed limiter, perhaps with a keyed switch, to allow kids to drive the vehicle safely. (Again, people smarter than me.)

Controller

Whomp! Here’s my “breadboard” showing everything. Batteries to power the motor, and a buck converter to drop the voltage to 12v for the Arduino and a cooling fan. The throttle connected to the converter and then to the motor controller to control things. We’ve also got a DPDT (double-pole, double-throw) switch in there to allow for forward and reverse to the vehicle, and a kill switch, fuse, and voltage meter. Basically all this will need to be jammed into the vehicle to control it. (Don’t worry, we’ll be using larger batteries, thicker wire, and a larger motor.)

Controller

Here’s the controller with a cooling fan mounted to it. I’ll provide files to laser cut or 3D print the mounting pieces, or templates to cut by hand, which is totally doable. (I learned the hard way last year that if not properly cooled the capacitors on these controllers can blow.)

Controller

I also added a bright blue LED to the board (you can choose another color) to indicate when it’s receiving power. Another suggestion I got from someone. I’m sure there is still room for improvement (like, you know, diodes) but hey, it works and I look forward to testing it.

You may remember version 1.3 of my Teensy Breakout Board, and some of the planned improvements I mentioned. Well, it’s a year later, so I should probably get around to actually talking about it.

I finished v1.4 last year, and I even had a bunch of them made via Seeed Studio’s Fusion PCB service, and they turned out great. We’ve been using them for numerous projects, and just recently I finally got around to the protective fix I added in v1.4.

Teensy USB Protector

I modeled this tiny part and 3D printed it. It’s got a hole for a screw, and two slots for zip ties. The photos below show the rest.

Teensy BOB v1.4

Teensy BOB v1.4

Teensy BOB v1.4

Teensy BOB v1.4

Okay then, the chance of the Micro USB connection getting ripped loose from the Teensy has been reduced quite a bit! The zip ties hold the cable end in place to the plastic piece which attaches to the fifth hole on the PCB. I’m looking forward to never have to see another Micro USB jack ripped loose.

Teensy BOB v1.4

Oh, and one more thing… I ran into Jasmine during Maker Faire and we talked about Tindie, and somehow she convinced me to start putting things up there, so now the Teensy BOB v1.4 is available on Tindie in case you want or need one.

The Noisy 85s

I posted just a bit about the ATtinyNoisy boards I had made from OSH Park, but there’s plenty more to tell.

My original plan was to use CR2032 batteries with these, but I found it just didn’t have enough juice to make noise, so I tried using two CR2032 batteries and that didn’t work much better. I ended up grabbing a nearby 9 volt battery to test with, and that worked well, and since I had a bunch of 9 bolt battery connectors, I chose to use those ordered a bunch of new 9 volt batteries from Amazon.

When it came time to program and assemble all the boards, some of them worked, and some didn’t. I wondered if it was because some of the chips I got were from different vendors, including some on eBay that were probably counterfeit. I spent way too much time chasing the wrong problems until I figured it out. (Maybe you’ve already figured it out!)

When I originally tested with a 9 volt battery in the shop, it was an old 9 volt battery that was down around 7 volts. Do you know what the voltage rating for the ATtiny85 is? Well, it’s 2.7 V ~ 5.5 V. Yeah, I was trying to feed it too much voltage!

At this point I had soldered on the battery connectors and was staring at a dozen brand new 9 volt batteries. The board didn’t have room for a LM7805 voltage regulator and I didn’t have time to get new boards made. I ended up taking the 9 volt batteries and shorting them with jumper wires until the voltage dropped to about 7 volts, at which point they worked fine. Yeah, I just wasted lots of electricity to get them working properly. NBD.

Below is an example of what they sounded like.

The idea was to make a bunch of these, and put them in a space, and then interact with the space and experience the sound coming from different directions. You can’t really experience it through a video, as you need to be in the space and move through it to participate in the piece.

The code is dead simple, and just does an analogWrite to a PWM pin on the ATtiny to generate some noise.

// ATtinyNoisy

int piezoPin = 0;
int randomPin = 1;
int randomValLow = 0;
int randomValHigh = 255;
int interValLow = 1;
int interValHigh = 3000;

void setup() {
  pinMode(piezoPin, OUTPUT);
}

void loop() {
  randomSeed(analogRead(randomPin));
  analogWrite(piezoPin, random(randomValLow, randomValHigh));
  delay(random(interValLow, interValHigh));
}

The Noisy 85s

Each ATtinyNoisy unit was placed in a paper bag, and hung from a piece of monofilament fishing line with a binder clip. (I had plenty of binder clips around!)

Here’s a few more photos from the installation that I did at UWM’s Kenilworth facility during SHiN|DiG on Friday, December 16, 2016. With many of my installations (and work in general) I focus on cheap things, often simply presented. I tend to go with the theory that if you can’t make something large, make a lot of little things.

The Noisy 85s

The Noisy 85s

The Noisy 85s

The Noisy 85s

The Noisy 85s

Big thanks to (former) student Maks for helping with the install and uninstall of this piece.

Maks

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