Category Archives: EMSL Projects

New EggBot Software Version

We are pleased to announce a major revision for the EggBot software with several significant improvements. It is now updated to support Inkscape 0.92. We have also streamlined the EggBot menu within Inkscape and updated the example set.

We have a new SVG reordering utility, written from scratch. In addition we have improved the Hatch Fill extension, which can now provide neat connections between the endpoints of the hatching, for fast, efficient filling.

We also have a brand new version of Hershey Text, which converts full blocks of text rather than just single lines.

The EggBot documentation has been improved and updated to reflect these changes.

Linkdump: June 2019

School of fossilized fish

Stroke fonts from Quantum Enterprises

One of the features in our new Hershey Text v 3.0 software is the ability to extend it with new fonts.

One company, Quantum Enterprises, is already selling high quality stroke fonts that are compatible with the new Hershey Text, and ideal for use with the AxiDraw.

Their fonts are available in matched pairs: A TrueType (outline) font and a single-stroke SVG stroke font. The TrueType font works as a regular computer font, which you can use to lay out and edit text on your page. Hershey Text then performs automatic font substitution replacing the text in place with the matching stroke font.

Here is a sample of what one of their regular (TrueType) handwriting-like fonts looks like, as laid out on the page within Inkscape:

And, here is how that same text looks once rendered with Hershey Text into its single-stroke SVG font version:

The single-stroke text comprises a set of paths ideally suited to be traced with a pen. And finally, here is how that stroke text looks as plotted with the AxiDraw:

These new stroke font pairs, as well as custom fonts, are available to purchase directly from Quantum Enterprises.

The AxiDraw CLI and Python API

Following the release of our new AxiDraw software this week, we are pleased to announce the release of two additional software components that greatly extend the capability of the machine.

The AxiDraw software is now available in two alternate versions that may be helpful for developers or for anyone who would like to control the machine programmatically rather than through Inkscape: A stand-alone command-line interface (CLI) tool, as well as a full-featured Python library.

The AxiDraw CLI

The first new tool is the AxiDraw CLI,  a command-line API to drive the AxiDraw outside of Inkscape. Like the Inkscape-based software, its primary function is to plot SVG files. However, it is a stand-alone utility that can be driven from within shell scripts and other environments that make use of shell commands.

Once installed, plotting a file can be as simple as executing the following command:

axicli filename.svg

There are, of course, a breadth of different modes and configuration parameters available. We have written detailed descriptions of each of these options in our comprehensive API documentation. The CLI also supports the use of configuration files to quickly switch between different sets of parameters.

Since most common scripting and programming environments allow one to call shell commands like this, that allows the AxiDraw to be used directly within a wide variety of frameworks.

 

The Python API

The second new tool is the AxiDraw Python API. The AxiDraw CLI is written within Python, and we have both exposed and expanded upon that nucleus to create a flexible and powerful Python module, complete with its own comprehensive documentation.

Just like the CLI, the Python API can plot SVG documents; it can both read SVG files and accept strings containing SVG data.

It also has features that are not available within Inkscape or the CLI: It supports direct interactive XY control. You can use absolute or relative moveto/lineto type commands to control the AxiDraw from within your own programs. This is particularly useful for a wide variety of potential AxiDraw applications that are not writing or drawing, but otherwise making use of the AxiDraw as a low-cost motion control platform.

Hershey Text v 3.0

Some years ago we wrote a neat little Inkscape extension called Hershey Text. Hershey text could take a little bit of text that you would type and render it into stroke fonts, also known as engraving fonts.

We are very pleased this week to release an all-new version of Hershey Text, written from scratch, and far more useful, capable, and extensible. We have a comprehensive user guide for it as well.

Hershey Text v 3.0 will be bundled into future versions of Inkscape, but it’s also included with the new AxiDraw software and available on its own for download today.

Continue reading Hershey Text v 3.0

New AxiDraw Software v 2.5

We’re pleased to announce the release of the latest version of the AxiDraw software, 2.5. which includes a number of frequently-requested features that we’ve been working on over the last year.

An expanded user guide

Perhaps foremost, we have updated and greatly expanded the PDF AxiDraw user guide, which covers how to use the AxiDraw, including every part of the software. In addition to sections that go over the new features, we have thoroughly revised the rest, including a larger and clearer section on getting started.

A new SVG optimization tool

In normal use, the AxiDraw software plots elements in the same order that they occur in the file. However, depending on how your file was generated, that may not be the most efficient way to do things. If the order of the elements in the file is poor enough, the plot time can actually be dominated not by writing and drawing time, but by pen-up movements (illustrated here in red) between objects.

We’ve written a new SVG ordering utility, that can sorting of objects in an SVG document, re-ordering them as needed to reduce pen-up travel. It’s also a layer-aware and group-aware sorting tool, that can process a full document and reorder elements on each layer of the document and either respect or break apart other groups in your document. This tool is available in two versions: An individual Inkscape extension as well as an integrated version that you can use automatically within the AxiDraw software.

Better support for using multiple machines

The new AxiDraw software supports assigning names to individual AxiDraw units over USB, which you can use as semi-permanent labels when printing to a particular machine. You can also now plot to a specific AxiDraw, or simultaneously plot the same document to a number of connected machines.

A new version of Hershey Text

This release includes an all-new version of Hershey Text, our software for creating stroke-based text within Inkscape. You can about the new features in our blog post announcing it.

And more!

Amongst other improvements in the new software are the following:

  • Updated to use Inkscape 0.92
  • Paths in the document are now clipped gracefully and precisely at the boundaries of both the artboard (drawing canvas) and machine travel.
  • Supports more SVG object and layout types natively
  • Faster plotting on paths with very high vertex density
  • Online version check added
  • Improves behavior of Hatch Fill extension
  • Bug fixes galore

We recommend this new version to all AxiDraw users; you can download it for Mac, Windows, or Linux, following our guide here.

Looking back at Maker Faire

maker faire ribbons being displayed in a cabinet

It has been reported that Maker Media is shutting down and that Maker Faire is at its end. Evil Mad Scientist has its roots in Maker Faire, and has been presenting there from the very beginning, so it seems fitting to look back at our Maker Faire projects now.

For the very first event in April of 2006, we brought the Interactive LED Dining Table that we built when we moved to the bay area. The attendees were incredibly engaged by it and we had multiple people express interest in making one. In addition to bringing our table, Windell gave talks on atomic clocks and using POV-Ray. We were incredibly inspired by the amazing projects we saw. One exhibit that helped push us in the direction of our 2007 Maker Faire project was the incredible 3D printed sculptures by Bathsheba Grossman.

For the second Maker Faire, we brought the CandyFab 4000, a 3D printer that printed objects out of granulated sugar. We even printed one of Bathsheba’s designs with it. It was made from hacked together pen plotters and a car jack, and used woodworking, sewing, laser cutting and a variety of other fabrication methods.

For the Bay Area Maker Faire 2008, we brought a host of projects. We were working on a revision to the CandyFab project, and brought our work-in-progress for that. We also brought an assortment of our blog projects from the year. We hosted a BristleBot workshop in our booth: a table filled with motors, batteries, toothbrushes and tools. Our collaboration with Because We Can to make Interactive LED coffee tables was on display. By then we also had kits in the Maker Shed.

For the Austin Maker Faire 2008, we held workshops on making bat costumes from umbrellas and High-Tech pumpkins.

By the 2009 bay area event, we had the CandyFab 6000 completed: it was built from scratch with no scavenged parts, and produced food-safe output.

For Austin in 2009 we brought some simple solar circuits. The Austin event being close to Halloween made it perfect for projects like a microcontroller-driven, dark-detecting, solar-powered programmable pumpkin.

For Bay Area 2010, the Friday before Maker Faire was designated education day, and we did another Bristlebot workshop. For the Faire itself, we brought our Tabletop Pong game. We were also starting our collaboration with Bruce Shapiro on the EggBot which was there, too.

In 2010 both Detroit and New York were started. For Detroit, we exhibited the EggBot with Bruce next to an optical player piano roll reader which triggered car lock solenoids to play a digital piano.

In New York, we brought Interactive LED Panels in addition to EggBot, but EggBot was what caught the eye of the Martha Stewart show producers who were scouting Maker Faire for show ideas. They ended up doing a whole show featuring projects from Maker Faire, including the EggBot.

In 2011 we built a large scale recreation of the Digi-Comp II binary mechanical rolling ball computer from the 1960s. It was a huge hit. We taught so many people about binary math. We were working on it right up until the faire, with friends over to help us assemble it, and then disassemble it to fit it in pieces into our Prius to take it to the faire.

We took the prototype of our small scale Digi-Comp II recreation to New York.

The big Digi-Comp II was so much fun that we took it to bay area in 2012 as well. Our friend Schuyler spent much of the event running the machine and getting better at binary math.

In New York, we demonstrated our kits in the Maker Shed, giving talks about EggBot and showing many blinking LED things.

In 2013, we brought a new collaboration to the Bay Area Maker Faire: the WaterColorBot. Our friend Zeph, who had been coming to Maker Faire since being a baby, also took it to RoboGames and the White House Science Fair. (Aside: we’re super proud of Zeph, who just graduated from high school last week.) Part of what has been amazing about Maker Faire has been working with the young makers.

For New York, Atmel invited us to exhibit in their booth. We brought our Octolively modules, which use an ATmega164 microcontroller and is a descendent of our first maker faire project. We also brought along our then new Three Fives kits.

At Bay Area 2014, Windell gave a talk on Open Hardware Best Practices, and I hung out with the amazing Meredith Scheff-King with a bunch of soft circuit projects.

In New York that year, I was on AnnMarie Thomas‘s Making Makers panel, and Windell participated in the Let’s Make Robots booth.

For Bay Area 2015, Windell had just published The Annotated Build-it-Yourself Science Laboratory and gave author presentations about the book. I hosted a panel looking back at Ten years of Maker Faire with a bunch of the keystone figures from the event over the years, including Stephen and Fritz of Diet Coke and Mentos fame. The robotics team we were mentoring was also exhibiting that event with WRRF.

For the 2015 New York Maker Faire, Windell again gave author presentations, and I helped out with the MakerEd booth.

We brought perhaps our most elaborate collaboration to Maker Faire Bay Area in 2016. This was the debut event for the MOnSter 6502, a transistor-level recreation of the MOS 6502 processor, masterminded by Eric Schlaepfer. We were also at that time collaborating on the AYAB project, to provide modern interfaces to vintage knitting machines. It was on display in the booth for the Machine Knitters Guild of the San Francisco Bay Area. Windell also did another author talk.

In New York, Microchip invited us to exhibit in their booth, and we brought the AxiDraw, which runs on a Pic microcontroller.

For Bay Area 2017, AYAB returned with the machine knitters, and the MOnSter 6502 came out to play with a new, more capable machine to work in, along with demo programs to show it off.

2017 also featured the New York debut for the MOnSter 6502, and east coasters had their first chance to play with it.

For Bay Area 2018, we endeavored to make the small visible: we brought microscopes and decapped ICs for our Uncovering the Silicon project. Many people got to see inside of chips for the first time. We brought interesting looking chips as well as popular ones like the MOS 6502, the NE555 and the μA741. We also brought along large scale examples of some of the decapped chips, including the MOnSter 6502 and the Three Fives and XL741 kits.

At an earlier Maker Faire, our friend Matt Stultz hosted a Peanuts-style “Ask a Maker” booth. Inspired by that, but wanting to reach a larger audience, I hosted an Ask A Maker panel at Maker Faire New York 2018. I was privileged to host a great panel of folks, including Matt, Sophy Wong and Jimmy Diresta.

Last month at Bay Area Maker Faire 2019, we brought together a dream team of makers to hone the Uncovering the Silicon project into a beautiful tutorial of what is inside integrated circuits. Mike Szczys of Hackaday got a great video of Windell explaining it, and if you haven’t seen it yet, it’s well worth a watch.

This brief walk through of our Maker Faire projects is by no means a complete history of our Maker Faire experience. We’ve attended many mini-Maker Faires. We’ve written for and been written up in Makezine and other maker publications. Our Maker Faire projects have gone amazing places outside of Maker Faire. We’ve made more friends, connections, and collaborations than we can possibly list here. And those will go on.

Linkdump: May 2019

Lego turing machine

Uncovering the Silicon: μL914

At the 2018 Bay Area Maker Faire, our project Uncovering the Silicon showed off a number of simple and complex integrated circuits (with rather large feature size) under the microscope. We had a great time helping visitors look at the features and get a glimpse of what’s inside those black box integrated circuit packages. To take this to the next level for this year’s Maker Faire, we decided to try and close the loop; to take one simple integrated circuit and elucidate its workings well enough that visitors to our booth will be able to see every single component of the circuit, understand their function, and relate it to the macroscopic behavior of the chip. For this, we picked what turns out to be a rather obscure chip: the Fairchild μL914, which is a dual 2-input NOR gate. This chip belongs to the resistor–transistor logic (RTL) family.

uL914 IC closeup in circuit

Here’s what the chip looks like. It’s in a funny old “glob-top” can package with eight leads.

pinout

Here’s the pinout; there are two NOR gates in the chip, plus power and ground.

uL914 IC package circuit with switches and LEDs

Ken Shirriff built a circuit with the chip to demonstrate its functionality. When we push either of the two buttons for one of the gates, that LED will turn off.

Schematic

Here’s the schematic diagram, adapted from the original datasheet. If you look at the left side, if either of those inputs goes high, the transistor pulls the output low.

uL914 dual 2-input NOR gate die photo

John McMaster decapped a few of the chips and sent us a die photo. He made a video about the process — no small feat. We’ll be bringing one of these bare chips and a microscope (equipped with both eyepieces and a camera) to Maker Faire.

For the macroscopic scale, we approached visualizing this circuit from a couple of angles: the physical structure of the chip, and the electronic structure of the circuit.

uL914 die model render

Eric Schlaepfer used the die photo to model the structure of the chip in CAD.

uL914 PCB version

Simultaneously, Ken designed a printed circuit board version for use with discrete components that maintained the same structure as the IC.

Individual transistor acrylic model Individual transistor acrylic model

Working from Eric’s CAD model, we built a single NPN transistor model from layers of colored acrylic. If you lift it up, and look through the transparent middle layers, you can tell that the emitter (red) is embedded into the top of the base (yellow) and does not go all the down way through it. (Transistors like these are planar: The emitter is above the base, and the base is above the collector.)

The top layer of this little model has labels for the collector, emitter and base. It is removable so that the layers of the model can be more easily inspected.

The model of the chip die includes a transparent cover representing the oxide layer, and that supports the metal layer with the wire bond pads on the edges.

One of the reasons that this particular chip is educational to look at is that there are a few unused components on the die. There are two unused transistors: one of them is unconnected, and the other is shorted. There are also several unused resistors (resistors are the dogbone shapes). The unconnected and unused components are easier to see, and provide a visual example that is useful for understanding what the connected components look like under the metal layer.

It is also fun to imagine what other circuits could have been made with different connections.

We glued most of the layers together, but left the top two layers removable so that it is easier to see the internal structure when the top is removed.

(Aside: we left out most of the epitaxial pocket material, because even though we used transparent acrylic to represent it, the layers of the components are much more visible without it present.)

Acrylic chip model top with metal layer

There are cutouts in the oxide layer where the metal layer connects to the circuitry below.

Acrylic chip model with hot glue bond wire example

One of the most noticeable things you see when you look at this type of IC under the microscope is the bond wires. We’ve used silver glitter hot glue sticks to represent them.

bond wire closeup

The glob of melted glue represents where the wire is bonded to the pad.

Acrylic chip model with hot glue bond wires

When you look straight down on the model with its glitter bond wires, it looks very similar to what you’ll see in the microscope.

Acrylic model legend

To round things out for our acrylic model, we made a physical legend to make it easier to identify all of the parts of the model.

uL914 discrete version switch and LED circuit

Once Ken got his PCBs back from our friends at OSHPark, he built it up with the same example circuit.

discrete circuit closeup

The PCBs turned out beautifully, and it’s great to see the familiar discrete packages on the enlarged circuit. Ken has published the PCB design on Github.

We hope to see you at Maker Faire this weekend!

Bonus: Ken laid out some hypothetical alternate metal layers to use the same die to create different chips.

Coffee Roasting for Fun

When we first started roasting coffee, we used the air popcorn popper method. We learned about it from Sweet Maria’s, which in addition to selling green coffee beans, has a wealth of resources for home coffee roasters. We gradually refined our method, even making a DIY coffee bean cooler. We also tried out a lot of different types of beans, buying samplers from Sweet Maria’s and making notes on which flavor profiles we enjoyed. Eventually we outgrew the batch size limitations of the popper method and we purchased what is the gold standard of home coffee roasting: a Behmor 1600.

The Behmor can roast up to a pound of coffee at a time, and does so reliably without fuss. Newer models are programmable, but this one has a few preset roasting profiles. I use the default one pound setting and normally roast about 0.9 pounds of coffee at a time. The canister I use for coffee weighs about 0.2 pounds, so when I put it on the scale (it’s handy having a shipping scale nearby) I aim for 1.1 pounds. This smaller quantity roasts a little faster than a full pound would, and I have a wider time window to stop the roast when it gets to the stage I like.

The green coffee beans (which smell grassy, a bit like fresh hay) go in the roasting cage which gets put into the motor socket so that it can be rotated to toss the beans around for even roasting. After putting in the chaff catching tray, I start the roasting process.

The chaff is the papery membrane around the bean that comes off during the roasting process. Roasting creates quite a bit of smoke, and even though the Behmor has a smoke-suppression afterburner to reduce the amount of smoke, I prefer to roast outside.

Roasting takes about 20 minutes and the cooling cycle takes another 12 minutes. Because this is basically a toaster oven and fire hazard, it should be monitored during the roast. I take advantage of this half an hour in the sun to call my dad or catch up with friends. It’s an enforced break in my usual routine when I get to listen to the local birds and enjoy the changes in the sky through the seasons. When the roaster is done, I pull out the chaff tray and it’s quite a mess.

Most of the chaff is collected in the tray, but there’s some still mixed in with the beans, and it gets pretty much everywhere when you bring the roasting cage out. This is another good reason to roast outside. The chaff will just blow away in the breeze and joins the leaf litter below the shrubs that line our little parking lot.

I shake the roasting cage repeatedly until the amount of chaff dwindles, and then I can put the roasted beans into the canister for storage until I need need them.

There’s still chaff in the roaster in spite of the chaff catching tray. I blow it out of the roaster and sweep it out with a small clean basting brush.

Once the roaster is cleared of chaff I put it away for the next time.

The coffee loses a lot of its moisture during the roasting process, and reduces in weight by about 10% or so. It also increases in volume.

We have two to three people drinking coffee and use about two to three pounds of coffee a week. The flavor of roasted coffee starts to deteriorate about six or seven days after roasting. Since I’m roasting as needed two to three times a week, it never gets past about four days old.

As our coffee bean usage increased, we started buying our coffee 20 pounds at a time, but eventually realized that even that was seeming to be a little frequent. We had settled on the flavor profiles we enjoyed most, so we started purchasing 50 pound bags from Sweet Maria’s wholesale site, the Coffee Shrub. Green coffee has a long shelf life when stored well, so this means we don’t have to think about it very often. When you buy for several months at a time, you need to be confident that you will be happy with it. When we first got started, we didn’t know what we liked well enough to commit to purchasing at that scale, but we’re pretty set in our ways now.

Occasionally someone will really enjoy a cup of coffee I make for them and will say that I should start a coffee shop. It’s a well-intended sentiment, and I take it as a compliment. However, starting a coffee roasting business or coffee shop would take away many of the things that I love about coffee roasting. I only roast the kind of beans that we like, and I only roast as much as we need. And I get to use roasting as an excuse to take a break from my other responsibilities and enjoy being outside in our beautiful weather here.

I still enjoy trying other coffees. I love going to my favorite coffee shops and having someone else make me coffee. I love trying new coffee shops. And I get a lot of satisfaction from the coffee that I roast, grind, and brew myself.

If you’re interested in home roasting, I highly recommend Sweet Maria’s resources. In addition to working with farmers around the world to source beans equitably, they share their deep knowledge freely. They have articles, tutorials, and videos. They hold workshops at their warehouse in Oakland, and will be presenting at Maker Faire as they often have in the past.