Laser Money

Very quick post here because I'm about to leave for China in an hour, but I had to show y'all this because it's so neat. My new laser cutter, as it happens, accepts exactly the same DST files as the quilting machine. So what happens if you give it Nina's $1000 bill pattern?

Well, it works. This thing is fast!

Here's the final result:

More later.

6-Cylinder Radial Engine

Boy is this fun! Today's model is a 6-cylinder radial engine:

It's made with two layers of 1.44mm (rather thin) and one layer of 5.28mm (about 1/4" thick) acrylic. The pistons, link arms, and star-plate in the center are all cut in-place in operational arrangement (as in the CAD file above). In other words, you can simply slide it out of the laser cutter (being careful not to let any of the parts drop) and it works. Here is the main layer in raw form, with the protective film still on:

Getting the top and bottom plates screwed on is a bit tricky, but here it is all assembled:

The disk in the center is basically the crank shaft bearing. It's the rotation of the big disk within the cutout circle that keeps the crank shaft rotating about its center. The offset hole then caries the star plate around its orbit, operating the six pistons in order. (A certain wag who shall remain nameless complained that there were no operating valves, so I declared it to be a 2-stroke engine whose valves are just holes (not shown) in the cylinder walls.)

What blows me away is how smoothly this thing operates. I did not trim, sand, polish, or in any way manipulate any of the operating parts: everything is exactly how the laser cutter left it. All I did was add the nuts and bolts to hold it all together. Watch this!

Who needs a fidget spinner when you have a 6-cylinder spinner?

Although I had always been planning to make some engine models, I admit that the details of this one were inspired by this really cool cardboard version. Which reminds me that I need to add some engraved details around the cylinders.

Meanwhile, my cotton field is doing nicely. I weeded it this afternoon and it's looking good. A transparent cotton gin is next in the list of projects for the laser cutter.

Visible Lock

My purpose in getting a laser cutter was to make visible mechanisms, in order to make their operation clear. Here's the second example I've been working on: A visible pin-tumbler lock. With the key out, pins block the "core" from moving. But when the key is put in, the pins are all lifted to just the right height so that their tops line up along a "shear line". In a typical padlock, the core is then free to rotate, but in this version (as in some bike locks, for example), the core can instead slide out far enough to free a latch previously held in piece. Watch the video and it will all make sense (which is of course the whole point of making these things).

What the video doesn't show is that you can also pick this lock in the traditional way, by tensioning it (pulling gently on the core) and then using a thin tool to lift the pins one at a time until you find the one that is binding, then repeating until they all clear.

By the way, notice that the "springs" are completely bogus. In a real lock, springs push the pins down, but in this one the springs just act like small weights. The lock has to be held vertically so gravity can act in place of springs. Why did I do it that way? Because I haven't yet been able to figure out how to make acrylic springs that are weak enough to work for this situation. Everything I've tried has pushed way too hard, making it impossible to insert the key without a lot of wrangling. Acrylic is a terrible material to make springs out of, though I did get some extension springs to work pretty well in my previous mechanism.

Playing With The Laser Cutter

In my last blog post I reported on the arrival of my new laser cutter.... Today some videos of the first day and a half of playing with it. First let me say, this machine is AWESOME. I was expecting at least a week of frustration before it did anything sensible, but it basically just started up and ran right out of the box. I have not even had to touch the laser alignment despite its having been shipped across the country, tipped on its side, etc, since it was first put together.

It was a good call putting this thing in our side-building (a former drive-through bank, basically a bunker with bullet proof glass and a completely separate ventilation system from the main office building). It came with a powerful blower to extract fumes, and this turns out to be really quite important. Burning plastic smells terrible! I'm paranoid about setting things on fire, so I replaced the supplied plastic ducts with metal ones. The box in the middle is a water cooling unit that circulates cold water through the laser tube. (The shelf above it is the former money drawer, for passing things to customers outside in their cars. Sadly it doesn't work anymore.)

There is a lot of stupidity with file formats trying to get patterns into the machine, but that's not the fault of the machine, it would be the same with any model. Remarkably, in some cases I have had to resort to using the DST file format to transfer a design from Mathematica into the software that operates the machine. Why? Because bugs in Mathematica's DXF export make that not work, and I happen to have an elaborate body of code for exporting DST files, developed for use with our quilting robot. Why is this silly? Because DST is a decades-old format originally implemented on punched tape. It's limited to 0.1mm resolution, which is not good enough, so I have to expand the pattern by a factor of 10, then shrink it back down again. Oh well, I'll get some workarounds in place eventually.

Anyway, here is a video of the first real thing I tried to cut, a model of a spring-dial scale:

The version being cut here didn't work, but after several iterations I got a working device.

Making springs out of acrylic is sketchy, because the stuff is very brittle. But with enough zig-zags, I got springs that are able to stretch as far as they need to without danger of breaking. The scale is not "calibrated" in any sense of the word, and is super inaccurate, but that's not the point. The purpose it to let you understand how the mechanism works with a simplified, cross-sectional sort of mechanism. (When placed side-by-side with photos/videos of a real spring-dial scale, everything will make sense, I promise.)

After making the model scale, I started cutting and engraving transparent replacement dials to go on a pair of real scales (one spring scale, and one huge no-springs Toledo scale). My idea is to replace as many as possible of the cover plates and the dial face with clear acrylic, so that we can photograph the scales in operation, but you can see how they work inside. Creating the pattern for this involved spending a couple of hours carefully measuring the original dial, and writing Mathematica code to recreate the tick marks and letters as closely as possible. (Toledo uses a very strange font, and they are currently looking to see if they can get me a version of their old corporate font to make the numbers closer to the original.)

This scale dial is huge! 60cm, or nearly 24 inches, in diameter. Interesting, I think, that all the dimensions of the dial are clearly in metric units, even though it was made in Toledo probably in the 1950s. How did that happen? I have a book on the history of the Toledo scale company that will hopefully explain things to me.

Here's a picture of the smaller spring scale with its transparent replacement dial temporarily in place. Sorry for the mess, it's my garage. We will clean up and repaint (the scale) before taking the real pictures. Notice how the mechanism inside mirrors the acrylic model from above, except it's harder to see how it works. In both cases there are a pair of springs, and a rack-and-pinion gear system to turn linear movement into rotation of the dial pointer.

Next I'm working on a lock mechanism, which isn't working very well yet.

Meanwhile, Connor is having fun not cutting all the way through a piece of 1/2" acrylic. This is a time lapse of his depth test, varying the laser power level. I'm surprised how consistent the depth is. I didn't think you could do this with a laser cutter:

It's HERE!

It's Here!

It has parts!

It's huge!

It fit through the door!

It has a nice big working area!

It has a laser!

And a cutting head!

Yes, you guessed it, I just got a laser cutter! I'm so excited! I have no clue how to make it work!

This is a GU Eagle Advanced Automation model BF-1309 laser cutter, basically the small end of large-style laser cutters (it is, in fact, the smallest model offered by GU Eagle). It has a 130W CO2 laser tube, a water chilling unit to keep the tube cool, and a big blower fan to suck away the smoke and fumes from cutting whatever you're cutting. (I got a good deal on it from meeting the CEO on a recent trip to China.)

Why did I get a laser cutter? I'm starting on a new book project and I "need" it to make what I've decided to call "mechanical GIFs". It's too hard to explain what I mean by that, but hopefully pretty soon I'll have a couple that I can post images of (assuming the whole concept ends up working out as I hope it will).

Public Appearance at BookCon, NYC, June 4th, 2017

From time to time I get asked if I do public talks and the like. The answer is, yes, sometimes, but not a lot, and usually I forget to announce them in advance. This time I'm trying a new approach: Actually letting people know about it!

I will be appearing on a panel with two other authors at BookCon 2017 in New York this June 4th at 2:30PM at the Javits Center. Here's a page with the details:

Hope to see you there! (And if you ask nicely after the show, I'll probably let you look through a hand-printed copy of my new Reactions book. It won't be in stores until probably October, but I have laboriously printed and glued up one precious copy.)

Award-Winning Fan Mail

There's fan mail and there's award-winning fan mail....

As much as I appreciate receiving them, and as much as I have a fragile ego in need of constant stroking, I don't normally write a blog post when I get an email from someone who enjoyed my book. But this one is special.

Here's the email I got, followed by the text of said award-winning fan letter.

Dear Mr. Theodore Gray,

   In December of 2016, I had submitted a letter to contest, called the National Letters about Literature Contest. Letters submitted to the contest were about a book that had  changed your life, mine was your book The Elements. At the beginning of March I received an email stating that my letter had won for the state of Nebraska in the high school level. As of today (April 23, 2017) I have not received any notification regarding my letter's status on the national level. I have attached the letter, in the hopes that you would enjoy reading it.

Thank you,

Matthew P. Heaney

I course I immediately replied that, why yes, I did enjoy reading it, and would he mind if I put it on my blog! Here it is in all its state-level award-winning glory:

Dear Theodore Gray,

            Your every word, your every personal anecdote in your book The Elements: A Visual Exploration of Every Known Atom of the Universe was an atom of solder that created for me a connection to my own life goals. My life is like an incomplete calculator: there is a battery with a copper wire connected to it, and a silicon circuit board. All I needed was some tin solder to connect that wire to the circuit board. The solder I needed was your book. As I was reading I gradually started to make connections. Your book brought back pieces of my past and connected them to the present. Soon after making these connections I would understand my life goal.

            In our seventh grade yearly book fair, my science teacher came up to me and pointed at your book. I skimmed though some of the first few pages and then rashly bought the book. At home after I read your precaution to not drop the book on my foot, I became confused with the names of groups in the periodic table. Although too technical for me to understand quantum mechanics, it became something of a challenge and although I did not comprehend it the first few times, I kept at it. Unfortunately, I eventually had to give up and move on to the elements.

            Needless to say I was happy once I got to hydrogen, since I actually understood some parts of it. My grandfather used to print off astronomy pictures of the day and he would show them to me. I was reminded of these pictures by your choice to use the Eagle Nebula in your representation of hydrogen. My first practical application occurred when I was able to find boron samples around my house – Silly Putty and a boron carbide lock. Now every page became a new discovery to me. With carbon you mentioned that diamonds could make your lip feel cold since it was such a good conductor of heat. When my mom got home that night I told her I wanted to make sure her ring had a real diamond in it. I later assured her that it was. With that success I decided to melt objects to get their base components.

            Farther into the book I started picking up on low melting point metals and how you had melted zinc down on the kitchen stove as a child from scrap zinc roof flashings. However, as you well know in the 21st Century, not as many roofing products are made of zinc, and unfortunately there are no scrapyards near my house. I began to look for expendable (or so I thought) objects that were in my house. The only way I would find out if they were zinc was if I melted them in a pot over the stove. My first choice was a monopoly character piece because they sure looked like zinc, but to my disappointment they would not melt despite my best efforts. I tried to do some level of research as to find distinct characteristics of zinc versus other similar metals, and fortunately I also discovered that zinc, when molten and in contact with water, explodes. My mom is not fond of explosions so I read further, searching for some other metal that I could melt.

            I came across gallium, but its lack of applications in household items precluded further experimentation. Zinc and gallium were a depressing no but tin proved to be the experiment! I wanted to make a cast of something out of clay, similar to the tin soldier you made, so I used clay to make a rough cast of my finger. I placed solder in this basic cast, closed up the hole with some more clay so I could lay the cast on its side, waited for it to dry, and put it in a heated oven. It did not take long for the clay to start popping and shooting shrapnel all throughout the oven. I quickly turned off the oven, and was disappointed when the cast had cooled off only to find that none of the solder had melted. For the third attempt since I had determined that clay would pop and explode if it got hot, I used aluminum foil. I folded and shaped the aluminum around a pencil, and removed the pencil, then put a plastic funnel at the top. You probably know where this was headed. First the plastic funnel melted, and second, my completely exposed hand was right below the melting plastic. I immediately stopped, once I felt the really hot sensation in my hand. I was lucky that only molten plastic touched it, as the burn would have been far worse had metal touched it. My singed fingers and the mess in the oven dictated no more experiments.

            With that I came to the conclusion you had the resources that I did not, so I decided to observe things. With consistency and dedication I began to notice everyday objects differently. Sometimes on occasion when there was a sample picture in your book similar to something I had seen in my life, questions would start popping up, “Is that really vaseline glass containing uranium or is it just dye? Does this magnet have samarium in it or not?” These questions satisfied my ever growing curiosity. I began to love verbalizing these questions and was always intrigued to find the answers. In high school chemistry class I soon learned to love the experiments even more, and I realized how I could answer some of these questions by performing experiments safely.

            Also in my chemistry class I started to reread your book. I started using your book for reference and answers to questions I had which developed skills to find the answers on my own. By my sophomore year I was asked the question what I wanted to be. In nothing short of an epiphany the skills I had developed, this mindset of asking questions, my constant longing for knowledge and an affinity to chemistry, all came together and my "calculator" gave me my answer: chemist. The word resonates in my head. The idea of working with elements, and compounds, finding out what makes them do the things they do, makes me elated.

            Now I could simply tell you that in that moment my brain released a good amount of dopamine and some oxytocin mixed in that made this feeling so amazing, but it probably has also a large amount of non-chemistry related reasons too. I am a junior, I love chemistry, and I plan to go to college and major in chemistry, and then work towards a doctorate. This accomplishment would make me the first person in my family with the title doctor to be in the research field. The book that I had bought 4 years ago is no longer in my possession as it had become so worn down that there was no binding left, and was just a pile of pages. I have since acquired two more copies of your book. Your book is iconic to me as it plays a constant role in my life. It consistently keeps me going and reminds me of what I want be every day. When I am a chemist your book will still be with me in my mind and in my hands, but not on my feet.


Matthew Heaney, Grade 11

NOVA Kickstarter: Want to See Me In (Another) NOVA Show?

Just launched a few days ago is an exciting new concept: Getting people to pay for a NOVA show in advance through the Kickstarter platform, instead of nagging people to pay for it after the fact, during annual pledge drives!


I really hope you'll consider contributing now to see a better future (i.e. one containing this show, rather than the alternate future in which this show doesn't exist because you didn't contribute).

I don't think I need to tell any of you what a great pedigree this show has. NOVA is the classic science show. It's been running longer than many of you reading this have been alive, but times are changing and people need to step up and really wrap their heads around the fact that a lot of good things in the world are going to stop existing unless people actually do something about it. This is something you can do.

OK, enough guilt tripping.

I also want the show to get made so I can be in it! I was in the predecessor NOVA show, Hunting the Elements, and, much as my books Molecules and soon Reactions are follow-ons to my book The Elements, this new show is a follow-on about...molecules and reactions.

Speaking of me in NOVA shows, I was also just briefly in another one about batteries, which aired last week. You can see it online now:


I feel kind of bad about it because I couldn't get the batteries to explode as well as they used to. A lot of lithium ion batteries are actually much safer than the older types. They went elsewhere to find the more dangerous kind. At least good old lithium put on a surprisingly lively show! 

Anyway, back to the point of this post: Go give some money to and then feel good about yourself for helping make the world a better place.

Last New Elements Finally Named!

If you follow elements news, you already know that elements 113, 115, 117, and 118 now finally have absolutely final approved (by IUPAC) names. There is really no scientific significance to this announcement: The elements were all discovered years ago, and anything to be learned from them has already been learned (or at least is not dependent on what they are named). It was only the names that people were still arguing about.

So the real significance of the recent announcement is that we all (by which I mean all people who are in the business of printing periodic tables) finally don't have to worry about printing a new version ever again! After 140+ years of annoyingly having new elements added to it every few years as they were discovered and named, it is now complete, filled-in, finished, done, and never going to be changed ever again, period.

Unless someone starts discovering elements beyond 118, which would require a whole new row to be added to the design, completely messing everything up in an unimaginably annoying way. Please, if you are a scientist working on post-118 elements, please just stop. Go home, hug your kids, and find a new line of work. Global warming is a big problem, maybe you could work on that instead?

I'm kidding, of course, feel free to keep discovered new elements, because there's no way anyone is going to add space for them in the periodic table's standard layout. We'll just add a footnote somewhere in small type. That's what happened last time (in the mid-1900s) when the first element in a new row was discovered. It wasn't until that row was half-full that people finally proposed to actually start printing the table with that row included (thanks Glen Seaborg).

There is virtually no chance of enough elements beyond 118 being discovered to justify a new row. My secret belief is that the only reason people try to create these supremely impractical elements is so that they will get to name them. Once the researchers realize that the printers aren't actually going to give them new slots in the periodic table, interest in the enterprise will fall off.

For those of you with now-obsolete periodic tables from me, you can either (1) ignore it since who really cares, (2) wait until I print new versions, or (3) use this page to download images of the new element tiles to print and paste onto your poster. The only product you can actually currently buy from me that's been updated is the wonderfully soft and up-to-date Periodic Table Quilt (which you should get someone for x-mas anyway). Others will get updated as I and/or my publisher do new print runs over the coming months.