Category Archives: EMSL Projects

Two New Accessories for AxiDraw

We’ve just added two new accessories for the AxiDraw V3.

XL Pen Clip

The first of them, shown above, is the XL Pen Clip — something that we’ve had a number of requests for. The pen holder on the AxiDraw normally fits pens and other instruments up to 5/8″ (16 mm) in diameter. However, this new XL pen clip can hold instruments up to 1″ (25.4 mm) in diameter.

That is to say, it can hold things like this freaking huge marker:

huge pen

The second new accessory is a little more subtle: an Italic Pen Adapter that gives the AxiDraw a “right handed” grip on pens.

Italic Pen Adapter Italic Pen Adapter
Italic Pen Adapter Italic Pen Adapter

It’s a little bracket of anodized aluminum, with captured screws and threaded inserts, which rotates the AxiDraw pen clip 45° out from the X-axis of the AxiDraw. This angle can give a slightly more “natural” look to certain types of handwriting-like plotting.

Italic Pen Adapter

And of course, it’s ideal for use with various types of blunt-tipped pens, including chisel-point felt tip pens as well as pens with stub and italic nibs.

Both the XL Pen Clip and the Italic Pen Adapter are in stock at the Evil Mad Scientist shop. They join the Rigid End Effector and Tripod Mount on our AxiDraw Accessories page.

New Book: 10 LED Projects for Geeks

We just got our author copies of 10 LED Projects for Geeks! Our friend John Baichtal shepherded this book into the world as its editor, getting contributions from a great set of folks.

The book, published by No Starch Press, turned out beautifully. It has good pictures, clear drawings, and bright colors.

It brings a few of our classic projects onto the printed page, including LED-lit Sea Urchins, Electric Origami, the Dark Detecting LED, and Edge-lit Cards. Thank you, John, for letting us be a part of this!

Linkdump: May 2018

Linkdump: April 2018

Linkdump: March 2018

Lemon Ginger Marmalade

It is lemon season here yet again! Given the quantity of fruit my Meyer lemon tree produces, I have many opportunities to remake my marmalade recipes with little adjustments and changes. This time, I added ginger. Quite a bit of ginger. This jam has a bright cheerful flavor with a bit of zing to it which is perfect for the rainy weather we’ve been having.

Ingredients:

  • 8 cups (Meyer) lemon pieces
  • 1 cup lemon juice
  • 1 cup water
  • 3 Tbsp grated ginger
  • 2/3 cup ginger matchsticks
  • 6 cups sugar

First cut up the lemons into small pieces and remove any obvious seeds. After juicing lemons, we’ve found that straining it through a julep strainer holds back the seeds but allows most of the pulp through.

Our favorite tool for grating ginger is a fine microplane. For making matchsticks, a mandoline slicer makes short work of it.

Put the lemon pieces, lemon juice, water, grated ginger, and ginger matchsticks in a pot and simmer until the lemons start to soften. Add the sugar. Stir regularly and cook to the desired consistency. To test consistency, put a spoonful on a plate in the fridge. If it’s too runny after cooling for a few minutes, keep simmering and test again after a few minutes.

Makes about four pints. If you want to can it for longer storage, Ball has a nice introduction to canning on their website.


Other fruit preserves from the Play with your food archives:

Spaceship Cockpit with a Larson Scanner

Larson Scanner in panel with lights going back and forth

Lee at Sawdust and Solder is building a kids spaceship cockpit and used a Larson Scanner for one panel.

I wanted to spread out the LEDs over a large arc to simulate the sweep of a radar screen. The idea was to make it a scanner to look for other ships, class-M planets, or whatever is required. So I decided to mount the LEDs on the acrylic panel and wire them back to the board. I also decided to use my own switches mounted to the panel rather than the ones supplied with the kit. I used my Shapeoko CNC to cut out the acrylic panel.

Back of panel assembled with Kitt

After I painted and weathered the acrylic panel, I engraved the text (again, with the CNC and a v-carving bit) and then assembled everything.

CNC carved and weathered panel

There’s a ton of documentation and some good tips in the post. Check out the other parts of the cockpit project Lee has posted, too!

Evil Mad Scientist Valentines: 2018

2018 valentines

Today we are releasing our newest set of “Download and Print” cards for Valentine’s day. This is our sixth year, and sixth set of cards: The 2013 set had six equation-heavy cards, the 2014 set was a set of six symbol-heavy cards, and the 2015 set included love, hearts, and arrows. The 2016 set featured Pluto’s cold heart, and the perfect card for your robotic expression of love, and last year’s set featured atomic orbitals, exponential growth, and an epsilon delta declaration of love.

This year’s set features parallel lines, friction, and activation energy:

My love for you is at a stable equilibrium and therefore resistant to external perturbations

What could be more romantic than telling someone that the second derivative of your potential energy is at its minimum when you’re around them?

I'll Never be NP Complete Without You

The perfect card to give to any computer scientist when you want them to both (A) appreciate being given a valentine and (B) secretly wonder whether you don’t quite understand what np completeness means, or whether you do but thought it was funny.

Parallel lines never meet. But we should.

Parallel lines never meet. But we should.

It takes a special person to overcome my activation energy to send this card to you and ask if you will be my  valentine.

For when you have chemistry with someone.

Let's  measure our coefficient of kinetic friction

Why measure? Because it’s generally considered impolite to ask someone what their normal force is.


2018 valentines

You can download the full set here, which includes all 36 designs from all six years (a 1.6 MB PDF document).

As usual, print them out on (or otherwise affix to) card stock, personalize, and [some steps omitted] enjoy the resulting lifelong romance.

Using the WaterColorBot to teach programming

Water color painting titled Ocean Woman
JR has been volunteering in a high school programming class and wrote up a thoughtful post about his experiences using the WaterColorBot in the classroom. He wrote a Python library that allows users to directly control a WaterColorBot by writing Python code.

To be honest, this library is a pretty insane way to control the bot. It’s needlessly low-level: you’re manually controlling the brush’s position, you’ve got to remember to wash and re-ink the brush every so often, etc. If your main goal is to just get the bot to paint a pretty picture, there are lots of better ways to go about it.

As a teaching aid, though, it’s been a total success, because it lets students flex their burgeoning Python skills and actually make a real thing in the process! We’ve been blown away by the stuff our students have created.

He has also documented and shared his code on github.