Finally, CNC toast!

hello, world
One small slice of bread, one giant leap for toasters.

A few weeks ago, we rounded up a bunch of high tech toasters and wrote about about using a hot-air gun to draw designs, by hand, on fancy toast. We’ve now mounted the hot air gun to a computer-controlled X-Y control system so that we can use it to print arbitrary images on toast.

The hot air gun that we’ve used is actually intended to be the printing head of our 3D sugar printer, where it serves to selectively fuse the printing media together.
Recently we succeeded in mounting the hot air gun to the carriage of the printer. The next step was testing the XY motion control system without the Z axis installed.

It turns out that you can actually do some interesting things with just the print head and the X-Y gantry. Especially since, as one of our astute readers noted in a comment, “(3D printer – Z axis) + hot air rework station=completely digital toast imaging technology.” Our thoughts exactly.

We certainly aren’t the first ones to aim for true CNC toast– A group of students at Olin College apparently were working towards that goal a few years ago, but may have given up in favor of their laser cutter– which is (we think) cheating on building a CNC toaster. (Don’t get us wrong– We are of course very fond of laser cutters– they can be used to cut cake, or engrave matza, or just about anything else. Whether merely ablating away part of your bread with a high power CO2 laser should count as toasting is perhaps debatable, but it’s certainly an expensive way to make breakfast.)
H(ello) W(orld)   hello, world

Hello world!

To begin our 2D testing, we placed a cookie sheet where the Z axis of the printer would normally go. We had to stack a few pieces of bread on top of each other so that the top piece would be at the correct level to be printed on, just a few millimeters below the heat gun nozzle.

Our resolution for these tests was 10 dots per inch (2.5 mm pixel size).

Toast face (dark)Next, we tried out a photographic subject. When we thought about what face we’d expect to see staring out of a little rectangle, the clear choice was Ze Frank.

We pulled a great still from this article about small screen movies. (It is, of course, a still from The Show with zefrank.)

Toast face (light)
Getting an image to print correctly took several things going right: a good image, and adjusting the air flow rate, temperature, and the length of time spent on each pixel. Here is the actual image that we printed, 55 x 42 pixels:

Quite a bit of fine tuning was necessary to get the correct amount of darkening to show the image best.

We made a short movie of the toast-printing process, 1:18, no sound. You can watch the hot toasting action on YouTube or embedded here:


sunflower papad

One of the other cool things that toast visibly is a papadum. It’s a nice round canvas. I drew a sunflower in Inkscape and scaled it down to make a good test subject. I used large dots in the middle (not a grey or a set of small dots) so that when it reduced, the pattern in the middle was still visible.


It even shows up nicely on the papadum.

holding down with magnets
Unfortunately, while the papadums toast very easily, they get flexible when heated and tend to curl. To counteract this tendency, we held them down to the cookie sheet with magnets. This was tricky– the papadums are brittle!


Toast toastIf you perform a Google search on the terms CNC and Toast, one of the top hits is our friends at Because We Can. Not that they are making CNC toast, but they score high on those terms because they make things with a CNC routing table and one of the cofounders is Jeffrey “Toast” McGrew. I adapted this photo and printed it on bread, so we made a piece of CNC Toast toast for Toast. (And yes, we gave this piece of Toast toast to Toast).
Toast on the cooling rack

31 thoughts on “Finally, CNC toast!

  1. 1) Totally wonderful

    2)have you done a Virgin Mary yet? They go well on Ebay I hear.

  2. I’m reminded of a cut scene I saw in Game Sauce that featured MDK 2. A scientist was working on something and the viewer could see only his back. Moments later he turned around and cried "I made toast!" with the toast in his hand. Great work guys. Your penchance for evil never ceases to amaze me :D

    -Tim Ferriss-

    1. This could have happened in several TV shows as I remember it from Invader Zim.

      Dad: Not now son, I’m making TOAST!

      (with movements described similarly.)

      – Paul

  3. Ok, so CNC toast is a linear and logical extension of the work you’ve depicted so far. Seems to be well implemented and fun. I expect that you’ll be doing grayscale toast soon if you keep playing with it.

    But deciding that Ze Frank is the ideal subject for toast portraiture? Absolute unfettered genius. I applaud you and every person who has put you on your course in this world.

    1. And that was me. (And yes "this anonymous post is my post" posts annoy me too, but if I don’t claim it, I’ll read it in two years and think ‘hey, that is exactly what I would have said’.)

  4. I’m one of the Olin College students who worked on the project as part of our Sophomore Principles of Engineering course. It’s good to see someone else has picked up our noble cause. The laser cutter was actually just used as a proof of concept when testing a variety of heating elements, so it was really the beginning, rather than the end, of our project. That being said, it certainly produced the best looking toast. One of our chosen design goals was to have all the elements fit in a standard toaster, and to interface via USB. This would allow anyone to use the product and present a familiar user interface for those days when you just want regular toast. The project was ultimately unfinished, but we had a good time trying. Good luck with your printer.


  5. Dang. I wish I’d had some of *that* toast to offer at your wedding. =D

    I hesitate to think what might be done with Peeps.

    — Dave

  6. Great! Could you print menus on popodums for restaurants?
    Also, I’d like to try this but using an array of small heaters – a billboard but with heating elements instead of LEDs. Any ideas of what could be used as small heaters? I had a look at induction heaters and theses could be made very small



    1. Pappadums produce large bubbles when cooked, so it’s hard to imagine getting much better than 20 dots per inch (1.3 mm pitch). If your menu only has two or three items on it, that might be okay. Better would be to print the restaurant logo on it!

      I am also interested in an array of small heaters, but I have not yet found any (off the shelf) that look promising. Almost certainly, they would have to be custom-made elements, which would not be a problem if the volume were high enough.

      Windell H. Oskay

  7. Fortune Toast anyone? Or get your horoscope printed on your toast automatically each morning.

  8. Not now, son! I’m making….


    Sorry, I couldn’t resist an Invader Zim reference. It was just too damned appropriate.

  9. can a waffle printer available for public purchase be next? I would really love waffles with subliminal breakfast messages in them…

    from :
    a concerned citizen.
    p.s. you all have made my day a lot better. :)

  10. You mentioned that it took a little work to get the settings right for scorching it properly. Did you consider putting a colour sensor of some kind on to detect when it had been burnt to the appropriate colour? This could also allow for more complex images with more levels of colour to be made.

      1. Maybe you should pre-filter the input image. Surely a localized convolution filter could help to compensate for the fact that adjacent pixels become partially cooked.

  11. There must be a way to paint a design on the toast with something that will brown faster than the unpainted toast. But I can’t find any information about what to use.

  12. I want, one, and I want one now!!

    Instead of Post it notes, you could print messages on toast in the morning, to put in your top pocket. They wouldn’t be called post-it notes, but toast-it notes! After reading, eat them.
    p.s. Don’t butter them before inserting into top pocket.
    Still want one……sigh!…..

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