Freeside Atlanta

A Winner Is Us!

2013-05-07T08:43:00.000-07:00

We just got the news we won a LulzBot AO-100 3D printer as part of their giveaway contest!

Our submission landed us a spot in the 8 finalists out of over 200 submissions. We even got a shout-out about Dr. Glass' original medical research!

Check out the announcement!

This Week at Freeside, April 15-21

2013-04-14T16:38:00.000-07:00

Tuesday [7:30p]: CNC Build Project, Public, Free.

Freeside veterans, Preston and Eldon, will be leading this project to assemble and tune a smaller CNC for high-precision work, then design and build a full-size 4' x 4' CNC mill for the space as well.

http://www.meetup.com/Freeside-Atlanta/events/113727692

Tuesday [7:30p]: Open House, Public, Free.

We host this meeting every Tuesday so that people can check out the space, chat with members of the organization, and get together to plan projects, events, and classes.

http://www.meetup.com/Freeside-Atlanta/events/113155422/

Tuesday [8:30p]: Introduction to Basic Electronics, Public, Free.

Chris Moore and Wayne Salhany explain basic electricity and electronics concepts that you can use in your next project.

http://www.meetup.com/Freeside-Atlanta/events/113583832/

Friday [8a-6p]: Telecommute from Freeside, Members-Only.

Members, come join your other telecommuters at Freeside and “work” remotely.

Sunday [3p]: Burners Without Borders, Public, Free.

Freeside turns the auditorium space over once a month to Burners Without Borders for their monthly meetup, where they plan fundraisers, community outreach, and reconstruction/beautification projects.

http://www.meetup.com/Freeside-Atlanta/events/114326022/

What Freeside Needs this Month, April Edition

2013-04-02T09:28:00.001-07:00

Have you been itching to donate things to Freeside, but you’re not sure what we need? Have you been looking for volunteer opportunities to use your awesome skills? This monthly post shall be your guide, henceforth!

Look for all these things in our up-to-date Wishlist, the next time you're out and about and wondering what extras you could throw in the cart to bring on down!

We're always looking for new opportunities to facilitate projects/education in the space. New equipment can help us do that, so we decided to make a wishlist of some of the things that we need for the space.

Volunteer Opportunities:

Electrical wiring: running new outlets, and...other activities...
Woodworking, construction: help with shelf/hutch building for electronics, help with member storage build-out
Mural Art: artists, pick a spot on the wall and make it yours! We also want input on designing logos for each of our zones

Consumables:

ABS: Our 3D printers need more spools in a variety of colors
Batteries: 9V
Paint (dark, black, matte): for shrouding the stage in the darkness
Paint (brighter colors especially, not black/grey/white): we are painting an internet meme explosion mural in the front bathroom, and Carrie needs more paint
Printer ink for the HP L7680

Software:

Recording and mastering software/hardware
Valid Windows licenses
VOIP solution for linking our Google Voice number (or similar service) to the space

Hardware:

Good, functional computers
Audio/lighting/DJ equipment
Interesting Human Interface Devices
Arduinos, other automation controllers or kits
Raspberry Pis: for use with the access control project, or with the informational kiosks like we have in the welcome zone
4+ port NIC card for rack system, or full system: we are trying to build a router to create subnets, see Alan or any IT staff person for details
Mounts for rack systems: stacking the pizza boxen on top of each other just won’t do
Larger LCD monitors, flat screen TVs: we want to put up informational kiosk displays around the space
Breadboards: some members have asked and are unclear if some “projects” could be reclaimed or if there are extra breadboards to go around
Folding chairs: for when we host large talks or events
Door and ceiling: for the classroom, to cut down on the noise
Door/Steel/Mesh: for the server room door, for peace of mind
Help with getting the existing phone system up and running, for being able to dial other phones in the space, and linking that to VOIP

Storage:

Member storage bins: We are getting new members! Let’s have a few bins at the ready to get them on-board
Small to Medium plastic bins: We can start subdividing or replacing cardboard boxes storing things in the parts storage

Materials:

Lumber: ask about specifics, but the two main projects that could use some lumber are for the electronics lab benches and for improvements to member storage
Engraving plastic: for creating signage with Randy’s CNC!

Equipment:

Pallet jack
Pottery wheel
Welding supplies
UV Curtain Material
Welding Gloves

Tools:

Hammer drill
Concrete bits
Painting supplies
Magnetic Sweeper/Pickup tool for the floor
1/4" Allen wrench (for the lathe)

This Week at Freeside, April 1-7

2013-03-31T06:06:00.000-07:00

This Week at Freeside

Tuesday [7:30p]: Open House, Public, Free.

We host this meeting every Tuesday so that people can check out the space, chat with members of the organization, and get together to plan projects, events, and classes.

http://www.meetup.com/Freeside-Atlanta/events/111247782/

Tuesday [8:30p]: Introduction to Basic Electronics, Public, Free.

Chris Moore and Wayne Salhany explain basic electricity and electronics concepts that you can use in your next project.

http://www.meetup.com/Freeside-Atlanta/events/111334442/

Friday [8a-6p]: Telecommute from Freeside, Members-Only.

Members, come join your other telecommuters at Freeside and “work” remotely.

Coming Up Next at Freeside

Please note that Analog Game Night moved, due to a schedule conflict! Analog Game Night will resume to its regular schedule of first Wednesday of the month starting in May.

2013-APR-10, Wednesday [8p-11p]: Analog Game Night, Public, Free.

Come get your board and/or card game on!

http://www.meetup.com/Freeside-Atlanta/events/111593912/

Super-Cheap and Effective Off Road Wheelchair Hack

2013-03-27T16:13:00.001-07:00

Last year for Alchemy, we decided to launch a really ambitious art project on a really short timeline. It almost didn't get done, but we were able to get it out just in time... and it worked!

Ferris, Abigail, and Robin playing with the
bubble generator

Our project was to build a different kind of art car. Alan got the idea to build an Off Road Wheelchair for our friend Robin, who is an anthropologist and a disability advocate, so that she could get around these outdoor festivals to enjoy all of the crazy awesome stuff that happens there. We did the first round of fundraising at the Alchemy Art Fundraiser (FB event link here) and afterwards Alan, Joy, and Robin set up a second fundraiser at Freeside. Once they raised the money (which still had us on a razor-thin budget), I picked up the project from there and managed the planning and build. As it turned out, I was in way over my head.

The idea was this - Robin had a really hard time getting around at these events and spent most of her time at her camp. She has partial paralysis on her right side, making it really difficult for her to get around, especially on uneven terrain. There's sooo much to see there, so we wanted to help her out. But we didn't just want to help her get around, we wanted make her the most intimidating and crazy-powerful vehicle out there so that nothing would stand in her way! It was our way of making a statement and drawing attention to the idea that Radical Inclusion means that not only should everyone be welcome, but everyone should be able to join in. The way we saw it, if we had the ability to make that happen, then we should.

A rugged, human-powered wheelchair can cost between $2,500 and $8,000. An electric or gas-powered wheelchair can cost upwards of $10,000. Our chair had to take steep inclines (including "effigy hill") and rough terrain on its own power, run reliably for 3-4 day events with spotty access to infrastructure, and have similar accessibility, controls, and behavior to a normal wheelchair.

This was a huge dilemma, which we discussed in detail in our first blog post on the project. The only reasonable solution for our budget was to modify a high-torque zero-turn lawn mower to turn it into a super-powerful, ruggedized wheelchair. It's not ideal, but it's a surprisingly effective solution... especially with a 2 month, $2,300 project.

Humble beginnings for a crazily ambitious project.

So we found a crap zero-turn mower and bought it without the deck for $1,400. It was ugly, had structural damage, electrical problems, body damage, rust, no lights, and was really heavy. However, it also has a 20HP motor and working hydrostatic transmissions that distribute huge amounts of torque to the off road tires independently, meaning that the machine can pivot in place similarly to a regular wheelchair. It was a substance-over-style decision.

After that was a massive series of builds. We had over 30 people work on the project on and off. As the project wore on, we hit bottlenecks and people lost enthusiasm. There were a lot of challenges.

We had a huge number of things to get done to get the project ready. We needed to repair mechanical damage, do some structural welding, remove rust, reduce noise, repair the electrical system, add running lights, and give it style. We added a trailer hitch as well, but couldn't get the right kind of winch to attach to it in time. We'll have to take care of that on the next round.

Kate was one of the leaders on the project and did a lot of
mechanical work, as well as getting the new seat done.

Even with as many people as we had working on it, the project took every bit of the 2 months that we were allotted, including an almost sleepless 72-hour burn to wrap things up at the end.

Safety was the major concern. Everything we did was weighed, checked, and re-checked. We wanted to push the limits of the system, but we wanted to guarantee Robin's safety in the process. So we developed a testing program for the machine and a training program for operators. We watched some safety videos from zero-turn manufacturers together and built a training course behind the shop to practice circles, reverse circles, figure-eights, reverse figure-eights, and 5- 10- and 15-degree inclines from all angles of approach. It was a full day of work even after all of the planning we did.

Originally, Albert from Carbon Age Designs had designed a front clip to attach to the chair to reduce the likelihood of the chair tipping forward. However, we decided that the attachment could bottom our and cause the chair to roll forward, so it was too dangerous to use. Instead, we opted to include an inclinometer on the chair and train Robin on how to use it to keep the chair under 15 degrees for the initial test run. We have time to refine it later.

Igor and Smitty's last minute work to get the project ready

For style we looked to Ferris, one of the Directors at Freeside, who came up with the idea of setting up LED strips on the chair that robin could remote-control. He hacked together a battery power and IR receiver system for it that would be waterproof and set it up. He also added a bubble generator on it so that it will leave a trail of bubbles wherever it goes. We'll try blacklight bubbles on the next iteration.

Finally the day(s) of reckoning came and surprisingly... everything went better than expected! It worked the entire 4 days, though we did have to change the battery out at the end. It worked exactly the way we wanted it to and Robin even got to see the effigy burn up close for the first time. In fact, there was no camp at the event that she wasn't able to make it to including Area 51.

Of course, I wasn't totally satisfied. It was too noisy and I had really high expectations of the final result. The hacker in me wanted to build it from scratch, but the project manager in me was pretty satisfied with the short turnaround and low budget. We've got plenty of time to make it quieter, prettier, and more sleek. In the mean time, it gets the job done really effectively. When it comes down to it, that's really all the project was about in the first place.

Special thanks to Robin for her support and patience, and everyone that put your hard work into this project! We're going to keep developing it for this year's burns and push this idea as far as we can to develop a cost-effective, safe, and outrageous powered off road wheelchair.

Robin, looking stunning on her chariot of torque and ready to rock on any terrain.

Surface Mount Reflow Soldering At Home

2013-03-17T16:17:00.000-07:00

This Week at Freeside, March 18-24

2013-03-17T12:46:00.002-07:00

Tuesday [5:30p]: CNC Build Project, Public, Free.

Freeside veterans, Preston and Eldon, will be leading this project to assemble and tune a smaller CNC for high-precision work, then design and build a full-size 4' x 4' CNC mill for the space as well.http://www.meetup.com/Freeside-Atlanta/events/109131302/

Tuesday [7:30p]: Open House, Public, Free.

We host this meeting every Tuesday so people can check out the space, chat with members of the organization, and get together to plan projects, events, and classes.

http://www.meetup.com/Freeside-Atlanta/events/109154682/

Tuesday [8:30p]: Introduction to Basic Electronics, Public, Free.

Chris Moore and Wayne Salhany explain basic electricity and electronics concepts that you can use in your next project.
http://www.meetup.com/Freeside-Atlanta/events/109104052/

Thursday [7:30-9p]: Building Interfaces between Computers, $10. Free for Members.

Chris Moore and Wayne Salhany help you design and build a "stack" that will bridge the gap between a laptop computer and a 110V 100W light bulb or fractional horsepower electrical motor.
http://www.meetup.com/Freeside-Atlanta/events/109485762/

Friday [8a-6p]: Telecommute from Freeside, Members-Only.

Members, come join your other telecommuters at Freeside and “work” remotely.

This Week at Freeside, March 10-17

2013-03-11T05:24:00.003-07:00

Tuesday [5:30p]: CNC Build Project, Public, Free.

Tuesday [7:30p]: Open House, Public, Free.

We host this meeting every Tuesday so people can check out the space, chat with members of the organization, and get together to plan projects, events, and classes.
http://www.meetup.com/Freeside-Atlanta/events/106718942/

Tuesday [8:30p]: Introduction to Basic Electronics, Public, Free.

Chris Moore and Wayne Salhany explain basic electricity and electronics concepts that you can use in your next project.
http://www.meetup.com/Freeside-Atlanta/events/106481602/

Thursday [7:30-9p]: Building Interfaces between Computers, $10. Free for Members.

Friday [8a-6p]: Telecommute from Freeside, Members-Only.

Members, come join your other telecommuters at Freeside and “work” remotely.

Sunday [3p]: Burners Without Borders Monthly Meeting, Public, Free.

Freeside turns the auditorium space over once a month to Burners Without Borders for their monthly meetup, where they plan fundraisers, community outreach, and reconstruction/beautification projects.
http://www.meetup.com/Freeside-Atlanta/events/107004372/

What Freeside Needs this Month, March Edition

2013-03-04T11:34:00.000-08:00

Paint (brighter colors especially, not black/grey/white): we are painting an internet meme explosion mural in the front bathroom, and Carrie needs more paint.
Paint (dark, black, matte): for shrouding the stage in the darkness.
Printer ink for the HP L7680
4+ port NIC card for rack system, or full system: we are trying to build a router to create subnets, see Alan or any IT staff person for details.
Mounts for rack systems: stacking the pizza boxen on top of each other just won’t do.
Lumber and other build-out materials: ask about specifics, but the two main projects that could use some lumber are for the electronics lab benches and for improvements to member storage.
Small to Medium plastic bins: We can start subdividing or replacing cardboard boxes storing things in the parts storage.
Member storage bins: We are getting new members! Let’s have a few bins at the ready to get them on-board.
Folding chairs: for when we host large talks or events.
Breadboards: some members have asked and are unclear if some “projects” could be reclaimed or if there are extra breadboards to go around.
ABS: Our 3D printers need more spools in a variety of colors.
Larger LCD monitors, flat screen TVs: we want to put up informational kiosk displays around the space.
Raspberry Pis: for use with the access control project, or with the informational kiosks like we have in the welcome zone.
Engraving plastic: for creating signage with Randy’s CNC!

Volunteers are needed with the following skills:

Electrical wiring: running new outlets, and...other activities... (certification required)

Woodworking, construction: help with shelf/hutch building for electronics, help with member storage build-out.

Mural Art: artists, pick a spot on the wall and make it yours! We also want input on designing logos for each of our zones.

Set a bookmark for our up-to-date Wishlist.

This Week at Freeside, March 4-9

2013-03-03T12:57:00.002-08:00

Tuesday [5:30p]: CNC Build Project, Public, Free.

Tuesday [7:30p]: Open House, Public, Free.

Tuesday [8:30p]: Introduction to Basic Electronics, Public, Free.

Chris Moore and Wayne Salhany explain basic electricity and electronics concepts that you can use in your next project.
http://www.meetup.com/Freeside-Atlanta/events/106481602/

Wednesday [8p-11p]: Analog Game Night, Public, Free.

Come get your board and/or card game on!
http://www.meetup.com/Freeside-Atlanta/events/106083922/

Friday [8a-6p]: Telecommute from Freeside, Members-Only.

Members, come join your other telecommuters at Freeside and “work” remotely.

Saturday [12p-?]: Members Meeting, Members-Only.

Our regular member’s meeting, to discuss Freeside matters and impact the space.

Craftycoder's Automotive PDU - Update

2013-03-02T13:28:00.000-08:00

I've been busy working on this project since I last wrote about it. I have a new PCB designed and built up and another that has since been designed but not yet built. Designing electronics is a process. The first design I had built had an analog mux on it that I was using to push all the current sense signaling to a few ADCs on the board. Later designs needed those pins on the MCU for other purposes so I added an 8 channel ADC to the design and removed the mux all together. I then found that the ADC was too fast to measure the current in a useful way because the PWM I use to adjust the current would give the ADC values that were either 0% or 100% instead of a working average. I knew this going in, but assumed I'd be able to get a reliable average in a reasonable amount of time. For whatever reason though, it took about 300 samples per channel to get an reliable average value. Multiply that by 8 channels and then assume a single byte to store the value and you can see that it consumes at least 2400 bytes (I only have about 500 to work with). It also took about a 12ms to get a value (there was a lot of overhead in the serial communication layer I had not accounted for). Multiple that by 2400 and it would take almost 30 seconds to get reliable current values from all the channels. That was a total epic fail. So, I went back to the drafting table and drew up a circuit that did all the averaging in the analog domain which operates WAY FASTER than any digital circuit can. What I drew up is a three stage low-pass filter for each channel. Image below.

Blue: PWM
Green: 1st Stage
Red: 2nd Stage
Celeste: 3rd Stage

As you can see, the circuit is not exactly trivial (especially if you consider I needed 8 of these added to an already crowded board; 56 more components). The PWM input signal is turned into a low impedance DC voltage source (with the help of an op amp) that is proportional to the duty cycle of the PWM signal and whose DC offset is proportional to the current draw. The second part of that is done with another op-amp and a very large but low impedance resistor and then I do a differential measurement to get the voltage drop across the resistor. I multiply that drop so that the upward bound is just below the top DC rail of the ADC so I get the most bits of resolution. Look up high side current measurement for more details on this. I used LTSpice to help select the values for the RC filter network. The values have a lot to do with the frequency of the PWM input and the speed at which you want it to settle. You can see from the above graphic that I settled on a filter that gives me a decently flat, DC like, signal that settles within 50ms of a current change. This is plenty fast for the purposes of a circuit breaker and should provide excellent user feedback as well. When they turn up a circuit they should see the current like move very fast. This is in fact the case and the video below will show that.

I had another exciting and problematic feature that has been a challenge to create. Market feedback suggested that some constant current capability would be appreciated. At first I thought I may be able to shoehorn this in with a software fix. It turned out to be just too slow to work. When you require constant current you really don't want to overshoot too far or you can fry your load before the circuit has a chance to moderate the current. On the latest iteration of the I added some pretty clever hardware constant current stuff by taking advantage of some features on the MOSFET driver that were for another purpose but could support a constant current function with a little external help. I thought about it for a while and drew up a circuit and had boards built but I never bothered to do ALL the math required to fully understand the circuit I designed. It turned out when it was finished that I didn't understand all the variables that controlled the timing of the circuit. I ended up with a perfectly adequate constant current source, but it oscillated at 20Hz instead of the 200Hz I expected. At first I thought I just dropped a decimal when I was doing the math because 20Hz and 200Hz look suspiciously similar. I redid the math and I had not screwed that up so I had to look more closely to see what was happening. I put it on the scope and then it became quite clear. Remember that 50ms number I mentioned about the settling speed of the 3 stage RC filter I created? Well, if you do the math, you will find that 20Hz is a synonym for 50ms. That was the problem. My filter was too slow to support the constant current feature I wanted to offer. I needed another 10x increase in performance. I knew this was going to be a big challenge and I also knew that my LMV324 op-amps (that were part of the circuit) were not going to be up to the task of moving so fast. I completely redesigned the constant current circuit with high performance op amps and much faster filter. I then went ahead and used LTSpice to model the circuit to confirm the design. This is a somewhat time consuming process, but these 4 layer boards and accompanying stainless steel stencils I am buying cost $200 and take about two weeks to get so its worth the effort to prove out the design before wasting all that time and money.

LTSpice is an incredibly useful tool for these sorts of electrical engineering problems. You can see that I am able to get reasonably fast PWM signal that is at a constant current over a roughly 100Hz time frame. The 100Hz speed is a compromise between the slow speed of the former version and fast speed that I desire. My secret sauce here is that I am using only 2 stages of the filter for this instead of 3 and I am adjusting the the first stages a bit. This is the compromise. I could other wise pretty easily get any speed I wanted but I'd have to have even more passive components on the board and its already packed with parts.
I suppose I"ll leave with a couple videos showing the circuit in action.

3D Printer Meetup, Program Line-Up - 02/09/2013

2013-02-06T11:32:00.003-08:00

Freeside Atlanta and My Inventor Club will be teaming up on Saturday, February 9th to bring you a daylong hackathon in 3D Modeling, Design, Marketing, Theory and more. This is a free, educational meet and greet event which will be hosted in Freeside Atlanta and My Inventor Club's space.

This is the (draft) speaker line-up and schedule of events! Like so many of these things, this is subject to change. Watch this blog or follow us on Twitter for updates and other announcements.

Cost: Free
Location: Freeside Atlanta, 675 Metropolitan Parkway Suite 6066, Atlanta, GA 30310
Directions, Parking, and other Information
Date: February 9th, 2013
Time: 1200-1700 EST
Contact: pr@freesideatlanta.org or info@myinventorclub.com

Speakers Track 1100~1500 Eastern Time (UTC−05:00)

This will be a Google Hangout invitation on the day of the event.

Nicholas Giovinco, Moderator - Freeside Atlanta
Greetings and Introductions: Welcome to Freeside
Time/Length: 30 mins 1100-1130 (UTC−05:00)

Shane Mathews - My Inventor Club
Topic: Prototyping Management: Strengths, Weaknesses, and Expectations
Time/Length: 30 mins 1130-1200 (UTC−05:00)

Shane Matthews, product development guru and founder of My Inventor Club will talk about the professional use of 3d printers, the difference between hobby and professional grade 3D printers and how 3D printers, MakerBot Industries, have impacted the professional community. In addition Shane will have sample prints from some of these printers to show the difference between the prints as well as prototypes casted from 3D printed part. Come see first hand some of the differences in 3d printers, ask questions and learn.
http://myinventorclub.com

Colleen Jordan - @colleeniebikini
Topic: 3D Designer Wearables and More!
Time/Length: 15 mins 1200-1215 (UTC−05:00)
http://www.colleenjordan.com

Clint Rinehart
Topic: 3D Scanning with Open Source Software and Microsoft Kinect
Time/Length: 30 mins 1215-1245 (UTC−05:00)

3D scanning is a common practice among 3D printing enthusiasts. This technology is no longer a limited modality with research or corporate funding, but now a practically attainable practice with a VERY low cost of entry. This talk will feature the use of a Microsoft Kinect device with ReconstructME software.

Chris Caswell - [carrythewhat?]
Topic: Replications: a case study on the basic economics of Distributed Manufacturing of Free & Open Source Hardware.
Time/Length: 15 mins 1245-1300 (UTC−05:00)

For 18 months now, our desktop 3D printers have been producing commodity prints and sold on the market. With 3 printers now, we are approaching viability as a self-sustaining business. But we have shown there is this small repertoire of digital goods, capable of desktop replication, and valued by the market -- set only to expand as replication technology advances and the software catches up. Along with our experiences so far, I will share my thinking on free & open source hardware, distributed manufacturing, and an open economy.
http://carrythewhat.com

Jason Webb - Graduate student, creative technologist, OSHW engineer
Topic: DIY mold-making with 3D printing
Time/Length: 30 mins 1300-1330 (UTC−05:00)

Learn how to design and 3D-print your very own low-cost molds, which you can fill with Jell-O, chocolate, silicone, resin, wax and more!
http://jason-webb.info

Emmett Lalish - Engineer or an Artist?
Topic: Designing 3D-printed mechanisms
Time/Length: 30 mins 1330-1400 (UTC−05:00)

I'll give some pointers on using OpenSCAD to design complex, printable mechanisms. I avoid using support at all cost and in my book, the order of coolness for mechanisms goes: bolt together, snap together, preassembled. The beauty of 3D printers is that they make preassembled mechanisms possible for the first time, but designing them requires thinking about shapes in a whole new way.
http://www.thingiverse.com/emmett

Mark Ganter - The Solheim lab Open3DP
Topic: AM in the early morning hours...
Time/Length: 30 mins 1400-1430 (UTC−05:00)

The Mechanical Engineering Department at the University of Washington is host to the Solheim Additive Manufacturing Laboratory. This lab hosts the Open3DP website. Open3DP's mission:to disseminate information and foster a community of people interested in an open sharing of 3D printing information. We hope that you find useful information on this site and that you will feel free to comment and share your expertise.
http://open3dp.me.washington.edu

Henry Thomas - “Wingcommander” WPThomas
Topic: General experiences getting my Replicator 2 to print reliably
Time/Length: 30 mins 1800-1830 (UTC−05:00)

Breakout Workshops 1500-1800 Eastern Time (UTC−05:00)

These courses will be held at both Freeside and My Inventor Club’s physical spaces.

Scanning with Microsoft Kinect
Instructor: Clint Rinehart
Location: Freeside Atlanta Worktable
Requirements: Self

A demonstration of Microsoft Kinect Scanning and Reconstruction with ReconstructME.

CAD, CAM, Print!!: Module 1
Instructor: Nicholas Giovinco
Location: Freeside Atlanta Classroom Zone
Requirements: Laptop and Creativity

This is part 1 of a two part workshop, centered on Computer Aided Design (CAD). In this, we will walk through a very simple design process in Google Sketchup of creating your very own Keychain. Choose a word or name and lets begin!

CAD, CAM, Print!!: Module 2
Instructor: Nicholas Giovinco
Location: Freeside Atlanta Classroom Zone
Requirements: Laptop and Creativity

This is part 2 of a two part workshop, centered on Computer Aided Manufacturing (CAM), where we work our brains around physical creation of our idea. In this, we will discuss the best methods for printing our designed keychain in a MakerBot Replicator 2.

zCorp 3D Printing via Cold Sintering
Instructors: Buddy Smith & Patch Trowell
Location: Freeside Atlanta Woodshop Zone
Requirements: Protective Eyewear is supplied and must be worn at all times

Additive manufacturing has many, MANY, applications and modalities. Hobbyist machines such as Makerbot and other Repraps utilize a derivative of Fused Deposition Modeling (FDM), but a lesser known modality is Sintering. The zCorp technologies found at My Inventor Club and Freeside Atlanta are capable of just such methods. In this workshop you will see and experience the basics of this technique applied.

Startup Your Prototyping Idea
Instructor: Shane Mathews
Location: My Inventor Club
Requirements: Interest in how to develop an idea

Discuss the first steps in taking an idea to a physical prototype, deciding on the best process to make a prototype including materials, fit, finish, number of evolutions, and other details of prototyping before moving to the next step.

CNC Milling Station #1
Instructor: Eldon
Location: Freeside Atlanta

CNC Milling Station #2
Instructor: Brian Cribbs
Location: Freeside Atlanta

Craftycoder's 8 channel automotive PDU

2013-01-11T14:56:00.000-08:00

I have been working a Bluetooth 4 automotive power distribution unit for a couple months now. Here are some videos showing the capabilities.

The goal is to have a device about the size of a deck of cards that can distribute up to 100A @ 13.8V for automotive applications. 8 individual circuits can be controlled. Control will include constant current, circuit breaker at specific currents, and PWM duty cycle. You will be able to program dedicated functions to external buttons. Lastly, you will be able to get real time feedback from the system on a Bluetooth 4 device. This data will include total current, current by channel, and system voltage among other things. There are a lot of features on the drawing board still.

This is going to have application in show cars, jeeps, motorcycles, and boats I believe. It's been a really fun project so far. I'm going to need about $120,000 to bring it to market so I want it to be pretty perfect before I write that check. I do hope I get that far.

3D Printing & Design workshop February 9th, 2013 @ Freeside Atlanta

2013-01-10T19:41:00.002-08:00

Come one; come all!

Freeside Atlanta and My Inventor Club will be teaming up on Saturday, February 9th to bring you

a daylong hackathon in 3D Modeling, Design, Marketing, Theory and

more. This is a free, educational meet and greet event which will be hosted

in Freeside Atlanta and My inventor Club's space.

What to Expect:

-Several Machine Technologies on display with instructional demonstrations

-Show and Tell examples of select prints and design prototypes

-Lectures ranging from Design Theory, Modeling Techniques, Printing Strategies, Troubleshooting & Community Experiences

-3D printing workshops and Hands on immersion

-Special Guest Speakers

Cost: Free

Location: 675 Metropolitan Parkway Suite 6066, Atlanta, GA 30310

Date: February 9th, 2013

Time: 1200-1700

Contact: pr@freesideatlanta.org or info@myinventorclub.com

-Nick

3D Printer Meetup recap

2012-11-26T19:49:00.003-08:00

We've had two really great 3D printing meetups lately, one to talk about and demo 3D printers, and another to help people build and debug them. Here's some of the stuff we saw -

Jorge brought in his Rostock Prisma to show it off and debug a few extruder issues. It's a really cool and fairly robust design. Plus, it's a lot of fun to watch! You can also check out the Thingyverse page that Jorge has put together for it.

We also had Ant's 3D printer and the Thing-o-Matic going, so people could benchmark or run off a few parts. James Stephens also brought in his RepRap Mendel to debug some extruder issues.

Randy did some work on his CNC, building a cabinet with removable side-walls for it, while Van continued working on his 3D Printer, the same variant as Ant's and the one that I am building for the space. I made slow progress on that, too, and it "only needs to be wired up" now.

That's all for now! Watch our Meetup page for more great events like these!

Precision Low Current A/C Measurement

2012-09-29T08:36:00.000-07:00

I got an interesting question on my YouTube channel yesterday asking if my transimpendance ammeter can measure A/C in addition to D/C and if the output of the instrument is A/C. The answer is yes to all of the above. Good question and a fun little thing to test on the bench on a Saturday morning.

Full power tests of motorcycle PDU

2012-09-19T20:04:00.000-07:00

I pushed 185 watts through my custom DC relays last night. They ate up that power like a champ. Likewise, I've also been testing it in the off condition to measure its steady off power consumption. The cards burn 150 nano amps or 1.8uW when off. That's means it's about 80 mega ohms which is OUTSTANDING. This project is really moving along nicely. I have some serious burn in testing to do and then it's time to get the main board encapsulated and do some real life testing. That's going to be fun!

Reflow Oven Demonstration

2012-09-18T09:39:00.001-07:00

Arduino Compatible Mini USB Host Board

2012-09-05T14:09:00.000-07:00

Well, its time to finally get this project "out there". I've been sitting on it for months putting together a bunch of cool little projects for this board and the video above shows off some of the cooler ones. Check out the Kickstarter page for more details as well.

Ever since I saw Kickstarter the first time I've been wanting to give this a shot so I could learn the ins and outs of doing small scale manufacturing from home. Because this is not a product, but a platform or hacker tool I am not super confident there is a substantial enough market for it but I cannot know if I don't try.

The plan if this succeeds is to give all the boards a final value engineering assessment and put the project out to bid. I've already done this with a Florida shop called Tropical Assemblies as well as with Seeedstudio. I'm not super excited with Seeeds PCB quality so I think I'll skip them but the good news is that the local fab shop had similar prices so at least I'll know that I can call and complain if anything goes wrong.

An issue has already cropped up with the Joystick shield. A part I used in the BOM is no longer available anywhere. I'll contact the vendor and verify its availability or lack thereof and reevaluate. I've already got a backup plan but it will require a two sided board which is going to kill the bottom line. No matter, this is more about learning this home manufacturing process then about any profit motivation so we are just going to drive it hard and fix what breaks.

Many thanks to Freeside for all the support and camaraderie.

Offroad Wheelchair Update 1 - To Retrofit or Reinvent?

2012-08-28T15:37:00.002-07:00

Recently, we at Freeside Atlanta teamed up with the Alchemical Arts Alliance and My Inventor Club to design and build an Offroad Wheelchair so that our friend Robin can get around their events. Together, we've raised about $2,000 for the project.

The design phase is usually the most difficult part of the projects, and it is often the most expensive place to make a mistake. Committing the resources to a poorly-designed project can cause the entire thing to be wasted, so we designed the Offroad Wheelchair project very carefully.

We started with the constraints – We need ease of maneuverability, an ability to overcome obstacles and take fairly steep inclines, longevity to make it through events up to a week long, and recoverability in case it gets stuck. Also, biggest two constraints – Budget (~$2000) and time to prototype (2 months)

From that, we landed on 3 design options –

1 – Electric motors with onboard generator for periodic battery charge

2 – Modifying an existing lawnmower or outdoor vehicle with hydraulic controls and automation

3 – Modifying a zero-turn lawnmower to suit our purpose

After weighing the options, we chose option one for its low noise and high efficiency. Next step - simulate the design. I used the website Study Physics to figure out the torque requirement to pull a simulated wheelchair + passenger up a given slope. Then I simulated it in a spreadsheet starting with the worst-case scenario so I could play with the numbers. The inputs are in orange and the rest are calculations.

In other words, the force required to take a vehicle up a 15 degree slope is a bit more than half of the force required to lift it all the way off the ground. To find the torque requirement, the force needs to be distributed around the wheel, since the wheel radius affects the leverage exerted by the motor.

Therefore, the minimum torque of the motors is about 200 pound feet. Is that feasible for an electric motor? Let’s look at the best motor example I could find -

This means that the system required two very powerful electric motors, running near peak torque continuously, and geared down 60x. They exist, but they are about $600 each and don’t usually match each other’s output exactly. Plus, the motor controllers are $200-$400 each! That means that this project is neither feasible nor practical, as the entire budget could be spent on 2 motors with their respective transmissions and controllers. It won’t work. But, this is why we simulate. It’s time to drop back and try again.

The hydraulic modification of an existing vehicle seems interesting, but also time-consuming. Plus, it wouldn’t be able to pivot in place like the other two design options, which is important to delivering the rider to exactly their target. Not to mention that the drive of the wheels will probably be locked together, so there is nothing stopping the thing from sliding down a slope. It also requires the modification of a ~$1000 platform with up to $800 in hydraulics and most options aren’t configured for somebody to easily get into from a wheelchair.

Then, Shane from My Inventor Club sent me an email about a zero-turn mower that was available in our price range. Zero-turn mowers use hydrostatic transmissions to convert the high-rpm, low-torque energy from an engine into low-speed, high-torque power with hydraulics. The mower we chose is a Grasshopper 725k. The actual torque isn’t listed in any of the data sheets, but the horsepower (25) and wheel diameter (22in) are. So now we just need to find the torque and update our simulation to see if it will work.

If we know how to find torque then we just need to find the rpm at the wheels at the top speed, discount it by about 30% for conversion losses, and that will be near our actual torque.

First, get the top speed to feet per minute –

Then, turn that to rpm using (the diameter of the tire) * (pi) to get the ground it covers per revolution.

Finally, you can do the torque conversion –

The zero-turn mower is 800lbs, so it is much heavier. The torque required to haul it up a 15 degree slope is 530 pound-feet, so it might be able to crawl along if it can keep traction. However, rolling over would be a concern at that angle anyway. Therefore, the zero-turn is feasible and reasonably meets the requirements of the project.

We can look into supplementing the power of the motors with a winch if the vehicle gets stuck somewhere that the torque/traction can’t overcome and reduce engine noise, but we're in the ballpark now. So, we’ve settled on a design – a retrofit of a zero-turn mower with a winch. It will be faster and more cost-effective to retrofit a used device that has been engineered to a similar task than to design and build something new from scratch. However, this platform could serve as a prototype for some future design, so we can work out the issues through iterative prototyping.

Until then, we’ll do the most effective and cost-effective Offroad Wheelchair that our constraints allow and document it so others can duplicate and improve the idea.

Check in on the Offroad Wheelchair page for links and info, including the simulation spreadsheet that I used (you get to point out my mistakes!) and the first video of the mower that we selected.

Precision Low Current Measurement w / Feedback Ammeter

2012-08-28T09:15:00.000-07:00

If you've been following along on my journey to learn electronics design, you'll know I've been working on a motorcycle power supply. It's getting pretty close to finished and its time to do testing. The last series of blogs were about a constant current load testing device. I needed that to test the power supply under different load conditions. This installment is about the opposite end of that spectrum, what happens when the circuit is "off". Because lots of motorcycles tend to be parked for months without being ridden I need to verify that my device does not contribute to early battery failure. To do that I need to measure the current consumed when it is plugged in but off. We are talking about very small currents though so very high precision measurements are required.

Normally, you can use a digital multimeter for this purpose but for measuring small currents this not as straightforward as it seems. Ammeters are connected in series with a circuit and while a perfect ammeter would neither add or subtract anything to the circuit, it would just observe, in the real world ammeters are not perfect. Standard multimeters use a current shunt, or a resistor in series, and measure the voltage drop across that resistor. These designs unfortunately introduce something called burden voltage. This is the voltage dropped across the resistor used for measurement. This can be kept at a minimum by using small resistors but it cannot be avoided with a shunt ammeter. When you try to measure small currents with a DMM you can sometimes get grossly under reported currents caused by the burden voltage of the measurement circuit. ¹

An alternate method is to use a feedback ammeter which measures the voltage dropped across the shunt and adds that much voltage back into the circuit. This sounds fancy but in fact is not that complicated once explained. That is my intention today.

Feedback Ammeter

The basic schematic above is the text book model of a feedback ammeter. A current goes into the inverting input (the current is represented here as a voltage in series with a resister which is the text book definition of a current) of an op amp and a voltage whose size is proportional to the input current comes out of the op amp's output as Vout. The burden voltage in this circuit would be the voltage difference between the inverting and non-inverting op amp inputs. Because of how op amps work though, this is almost zero.

This schematic makes it look so easy and I despite my best efforts to build it true to this diagram I failed to find success. The secret sauce is how you power the op amp. In order for me to make it work, I needed a floating power supply and I needed it referenced such that half of the floating power supply's potential was above GND and half was below GND. The wikipedia page ² offered the tidbit about the floating power supply. With that I was able to get a voltage measurement that was proportional to the current input but there was a DC offset that changed with the voltage applied to the op amps. Dave Jones' uCurrent device's schematic ³ offered the final missing piece which was the referencing the power supply to half the potential. Once I got that figure the circuit was a winner!

Useful resources:
www.keithley.com/data?asset=6169
http://www.ni.com/white-paper/5448/en

My schematic

Circuit on breadboad

Constant Current Dummy Load - Complete

2012-08-24T12:37:00.001-07:00

The project is finished. The units have been built and sent off for use. Much was learned. Here are some insights.

First, don't design a PCB for the lowest cost. That just increases your costs later. I made the the board narrower than was convenient to save $20 and I ended up wanting to put the entire thing a case so I could mount the banana adapters off the PCB where they could be farther apart. Not necessary but preferred for me.

Second, putting artwork in copper on your PCB not only works but looks great when you are finished. Take a look at the second photo below. That Freeside logo looks awesome!

Third, assembly of through hole components is NOT easier than surface mount parts. It was a bit of a pain to build them all. TH components don't stay in place when you flip it over to solder.

Final PCB I used.

Artwork in copper.

Queued up for soldering.

Delivered and installed.

My lab's version with voltmeter and case.

It includes a cooling fan.

Eagle Files
Code uploaded to the ATTINY85. It includes the RotaryEncoder lib I posted earlier.

#include <RotaryEncoder.h>;
int del=0; 
word outputValue = 0;
byte data = 0;
int val = 0;

int csPin = 0;
int sckPin = 1;
int siPin = 2;
int ENC_A = 3;
int ENC_B = 4;
RotaryEncoder encoder(ENC_A,ENC_B,5,6,1000);
void setup()
{
  pinMode(csPin, OUTPUT);
  pinMode(sckPin, OUTPUT);
  pinMode(siPin, OUTPUT);
  setDAC(val);
}
void loop()
{
  int enc = encoder.readEncoder();
  if(enc != 0) {
    val = val + (enc);   
    val = min(val,4095);
    val = max(val,0);
    setDAC(val);
  }
  delayMicroseconds(5);
}
void setDAC(int value) {
    outputValue = value;
    digitalWrite(csPin, LOW);
    data = highByte(outputValue);
    data = 0b00001111 & data;
    data = 0b00110000 | data;
    shiftOut(siPin, sckPin, MSBFIRST, data);
    data = lowByte(outputValue);
    shiftOut(siPin, sckPin, MSBFIRST, data); 
    digitalWrite(csPin, HIGH);
    delay(del);
}
void sinewave()
{
  for (int a=0; a<=4095; a++)
  {
    setDAC(a);
  }
  delay(del+25);
  for (int a=4095; a>=0; --a)
  {
    setDAC(a);
  }
  delay(del+25);
}

Raspberry Pi Headless Media Center

2012-08-18T11:13:00.000-07:00

Greetings fellow Raspberry Pi enthusiasts. I have something pretty cool to share with you today. I've been wanting to use the Raspberry Pi for a media center since I first heard about it. When Newark finally told me I could order the Pi I jumped at it chance and then promptly left town on a family vacation. My nephew Isaiah, who I met up with in Alaska while we were on vacation, discussed the media center project and how to implement it. Upon his suggestion we settled on running VLC. I had assumed we would have to get some webserver up and running and figure out how to slave VLC to our wishes but that is largely built in already. It is called the VLC Web Interface (or VLC http interface). That made this project all the more simple.

Below is the process to install it. This process assumes you have a freshly flashed Raspbian Wheezy (7/15) image that has NEVER BEEN BOOTED BEFORE. This made the most sense for us as we assumed you would plop this guy down somewhere and not use it for anything else.

Take a freshly flashed Raspbian Wheezy imaged SDCARD and put it in your Rπ
Make sure your WIFI adapter is NOT plugged in.
Plug in keyboard
Plug in Ethernet cable connected to the Internet
Plug in Rπ
Raspbian will boot up to the setup screen

expand_rootfs
configure_keyboard

Select keyboard that works for you (default is UK which is hard to use with a US keyboard) Images of this process are at the bottom of this post (its sort of long and tedious).

change_locale
change_timezone
ssh

enable SSH Server (not necessary but useful since its headless)

boot_behavior

So NO. You want to disable booting to the desktop

Reboot
Login as root. Type "root" at the login prompt.
Enter the commands below. (downloads and executes an installer script written by my nephew)
```
wget db.tt/rDy1S8Ga -O install.sh
source ./install.sh
```
It will prompt you the following things:
```
Press zero to set output to auto, press 1 to force headphone jack, press 2 to force HDMI.
```
I recommend you select 1 if you plan to use the headphone jack.
```
Would you like to setup the GPIO relay [y/n]?
```
Click Y if you want GPIO25 (pin 22) to go HIGH (3.3V) when VLC is playing. Pin 22 is positive and Pin 6 is GND. The numbering system is strange because it starts at 1. You want the third pins from the top and bottom on the outside. Refer to the photo below. SSR available at Amazon.com
```
Would you like to install rtl8188cus WIFI drivers [y/n]?
```
This is the driver for the WIFI adapter I selected. Available at Amazon.com
This driver installer was acquired from the Rπ forum and used with permission.
At this point the install actually begins. VLC takes a long time to download and install. Then, if you selected the WIFI drivers it will ask you a bunch of VERY IMPORTANT questions and PROMPT YOU WHEN IT IS SAFE TO INSERT YOUR WIFI ADAPTER. Please read and follow along. I found that if it pauses for a long time while it prompts you to wait for the adapter to blink and connect a quick re-plugging in of the adapter gets the system running again. The WIFI driver script ends asking you if you would like to upgrade your entire Rπ. I say no.
Unplug your ethernet cable (if you are using wifi).
Reboot.
Boot up screen will tell you what the new IP address is on Wifi. make a note of it. You can then use this address to talk to your Rπ from local devices on the network. You can setup a static IP if you desire by going to /etc/networks/interfaces and changing the
```
iface wlan0 inet dhcp
```
TO
```
iface wlan0 inet static
address *your ip*
netmask 255.255.255.0
gateway *your gateway ip*

wpa-ssid "*your SSID*"
wpa-psk "*your password*"
```

You can now find you VLC running at http://*ip address*/. If you want to see if from the actual Rπ you need to go to http://localhost:8080 but we went through the effort of updating the IPTABLES to forward port 80 to port 8080. The /home/pi folder is the default place it looks for music.

The GPIO stuff works by running a script that checks the VLC status stream and turns the pin on or off as necessary. I did this with one long shell command the executes every 300ms. There are no doubt many ways to do this, but I always liked AWK and | so that's how I did it (its below). You can find all scripts we wrote to make this work in the /root folder.

wget -qO- localhost:8080/requests/status.xml | awk '/<state>/ {if (index($0,"playing") > 0 || index($0,"paused") > 0) {print "echo "1" > /sys/class/gpio/gpio25/value"} else {print "echo "0" > /sys/class/gpio/gpio25/value"}}' | bash

One thing I should mention is that depending on your network speed, you may want to increase the buffering cache so you do not get skips during streaming playback. This is done by modifying the /etc/init.d/rc.local. Add the two caching arguments you see below (to the line starting vlc you'll find it in there somewhere)

su - vlc -c "vlc --intf http --daemon --disc-caching=20000 --network-caching=20000

These are some screen shots from the initial config. I found the keyboard part sort of confusing.

Roomba Wii Shield

2012-08-09T20:25:00.000-07:00

I've been working on an Arduino compatible Mini USB Host board. Well, I've had it done for a while now. I've slowly been compiling a bunch of projects for it so I can give it a cool Kickstarter one of these days. To that end, I designed a dedicated shield for controlling a Roomba vacuum with a Wii remote controller so that it might make the entirety of the project more compelling.

I'd already written the firmware and tested it with a chopped and spliced up cable a few months ago. It worked well for a while but one day the entire thing shot craps. My belief is that the on board voltage regulators could not handle the 16V the Roomba outputs (too much voltage to drop with an LDO without good cooling). So, for the dedicated board I decided to put a TO-220 7805 regulator with a heatsink on it. That should protect the main board from damage. I also had the idea of using optocouplers to isolate the Roomba signals from the shield. Optocouplers are ICs that contain an internal LED that turns on when a voltage is applied. That light shines on a photo detector which creates a voltage on the base of BJT opening a channel for current to run. This means two circuits can communicate without having any conductors between them. They isolate distinct circuits in effect. This seemed unnecessary but the board just had enough room and the datasheet gave the impression it would work (foreshadowing).

I built it up and put it together and I got nothing. The multimeter tests I conducted gave me no guidance either. I put voltage on one side of the optocoupler and I get a voltage out on the other side, or so I though. I put it on the oscilloscope and once again learned the value of good tools. The scope showed me that the clear problem was that the optocoupler is slow to respond. It can handle changes at human speeds but not a the speeds I was signalling. The initial speed was something like 300mS to drop off to 0V. That is glacial! The datasheet suggested 3µs was the expected value so I clear did something wrong. I read it closely and saw the RL needs to be 100Ω for that to work like that.

Time for a little rework.

I bodged up the board and got the voltage dropoff speeds into the 25µs range and was hopeful. I plugged it in and ended up with a Roomba that was, well, drunk. It moved slow and listed to one side. No dice.

I grabbed another board from the bag and built up a fresh one wiring around the optocoupler.

I bundled it up and gave it to my son Zev. Have fun son.

First flight of the Hexacopter!

2012-07-29T14:46:00.001-07:00

It's been a difficult journey, but we finally got the first flight of our DIY Drones Hexacopter. A special thank you goes out to the whole UAV team at Freeside Atlanta for donating their time, money, and resources to this project.

Slade, who did several hours of last-mile troubleshooting to get the UAV in the air, is flying it by hand. Check out the video on Youtube, which shows us testing the pitch, yaw, and roll of the unit and finally getting flight. We were pretty surprised at how smoothly it flies.

Stay tuned, as we'll be setting up and configuring the UAV controls so that it can follow GPS waypoint flight paths. We're also going to be posting another video that explains how everything works, how we did the troubleshooting on the initial flight, and some new in-flight footage.