Today’s post is about something that is flat-out easy and in addition somehow actually works. Specifically, we have some good news: You can create color 3D designs in Tinkercad and import them directly into the XYZ da Vinci Color 3D printer for printing! I know, that sounds obvious, but in general color printing is hard and even getting the right kinds of files exported can be a tricky business. This is one case where somehow the stars align and life is easy…
Here’s an example of a very simple design we made in Tinkercad, and the same design opened in XYZmaker and ready to 3D print in color:
XYZmaker is both a slicer and a rudimentary design program. Like any 3D printer’s slicer/software, you can use it to scale, place, translate, and rotate an imported design. But in addition, you can add geometric shapes, text, and symbols to the build platform, and combine them to make simple designs. It works a lot like Tinkercad, sort of like an alternate-universe version of Tinkercad. In XYZmaker it is easy to assign colors to each imported design and each element you build from scratch, and those colors will actually be printed when you send your design to the XYZ da Vinci Color Printer.
On the other hand, lots of people are already Tinkercad masters. For those people, the easiest way to create and print a color object would be to create and color something in Tinkercad, export it from Tinkercad, import it into XYZmaker with colors still intact, and then slice and print the design. Is this possible? Amazingly, YES! You can export any color design from Tinkercad into an .obj file, and have your design colors preserved and printable when you bring them into the XYZmaker software.
For people totally new to 3D printing, here is the basic process:
Will it blend? Well, with the Tinkercad technique outlined above, the answer is no; if you export from Tinkercad, then you’re going to get discrete areas of color, with only 36 possible colors. You won’t be able to blend the colors together to make new colors or smooth transitions. You can print in full blended color on the da Vinci Color printer, but you will have to use a different design program like Meshmixer or Blender to create the files.
Of course, the color of a 3D design on your screen may or may not faithfully represent the color of the resulting 3D-printed object, even if you’re using a full-color printer. To get a preview of what the Tinkercad colors look like printed on our XYZ printer, we created the Tinkercad color palette in Tinkercad (meta!):
Then we printed this color palette on the da Vanci Color printer:
You can create multi-color prints with dual-nozzle printers like the Ultimaker 3, or with filament-splicing add-ons like Mosaic Manufacturing’s Palette, but with those types of solutions you are still restricted to a small number of colors determined by the colors of plastic that you load into your machine. The XYZ da Vinci Color is just one example of a 3D printer that prints material that is then colored with ink. For example, the Mcor ARKe colors and cuts layers of paper to create 3D designs. If you have access to an ink-based color 3D printer, then you can test the colors on your printer by downloading and printing our Tinkercad Color Palette design from Thingiverse:
At Shapeways, you can upload a digital color design and have it printed on a fancy 3D printer in Full Color Sandstone, with layers of gypsum powder sprayed with a binding material and ink. Unfortunately, you can’t currently export Shapeways-friendly files from Tinkercad, at least not with Beta/current design files. If you have been using Tinkercad long enough to have a Legacy Tinkercad design in your collection, then you can create models in that file and export them in VRML format as .wrl files, which can be printed directly in Full Color Sandstone at Shapeways. To test out the colors, you can order our Tinkercad Color Palette from our geekhaus Shapeways shop:
Today we 3D printed some cylinder coins for students and classrooms to experiment with after watching Matt Parker’s video How thick is a three-sided coin:
These “fat coins” can land on their edges as well as their faces. Try out different thickness-to-diameter ratios and search for the fairest three-sided cylinder coin!
We made coins for five popular ratios with Tinkercad: the two ratios tried in the video, plus three inbetween:
We also made a parametrized version in OpenSCAD so you can try any ratio you like:
If you don’t have access to a 3D printer, you can purchase 3D printed sets of coins from our Shapeways shop, in the same ratios as shown in the Tinkercad photo above, or as a set of 10 coins that range in ratio evenly between the 1:2*sqrt(2) and 1:sqrt(3) ratios shown in Matt Parker’s video. To save on per-part costs, the 3D printed coins print in a cage which you can break open after shipping:
Here’s what the 10 variable-ratio coins look like after removal from their cage:
Students, educators, and experimenters: if you want to get involved and add data to Matt Parker’s collection, check out Matt Parker’s follow-up video Help me find the thickness of a three-sided coin!..
Today we’ll take a break from digital 3D design and do some good old-fashioned analog knitting. Here’s a stitch we’ve been working with recently, in progress as part of a simple scarf:
If you think there’s something weird about that stitch, you’re right: If you look across each row you’ll see that… there really aren’t any rows? The stitches kind of zig-zag up and down as you move from one side to the other.
The really cool thing about this stitch is that it is completely reversible, and in fact looks exactly the same on both sides:
So what is this crazy stitch, and where did it come from? We call it the Triple Check, and it’s a stitch we made up to solve a design problem. Maybe it’s new, maybe it isn’t; we aren’t sure yet, although we haven’t been able to find anything like it on the web or in our knitting books. If you’ve seen this stitch before, please let us know!
Our design problem was to find a simple knit stitch pattern for multicolor reversible scarves that we could knit during math talks and committee meetings. Specifically, we wanted a stitch that would satify all of the following conditions:
Of course the first thing we tried was finding such a stitch in the existing literature; no need to remake the wheel if there are already perfectly good wheels! However, in this case our literature search came up short, so we wondered… could we construct a suitable stitch pattern by deducing certain things from our list of desired conditions?
Somehow we did; here’s how the deduction process panned out:
Here’s the simple, reversible, three-color “Triple Check” stitch that resulted from our deductions:
All slipped stitches should be purlwise, whether the yarn is held in back (wyib) or in front (wyif); see the video Slip stitches wyib vs wyif for a demonstration.
Note that in each color we are only traveling along the knitting one time, in one direction; not going across the knitting and back again. At the end of the row just drop the color you are using and pick up the next color, which will be waiting for you.
So where is the carried yarn hiding under the slipped stitches? In the close-up image below we’re just done the s1wyif step, slipping a black stitch with the white yarn held in the front:
What happens next is that the white “yarn in front” strand needs to be wrapped over the black slipped stitch to the back of the work. Here’s the exciting part: When we wrap the white yarn over the black stitch, the carried yarn will make a white bump that lies exactly over an existing white bump from a previous perl stitch!
Every slipped stitch in the Triple Check pattern wraps over a bump of the same color in this way, either in front or in back of the work. The carried yarn under the slipped stitches is basically copying the “knit, purl” stitch of the 1×1 rib below it (which is luckily of the same color as the carried yarn), but without making any actual stitches. This color-matching on the slipped stitches is the secret sauce of the Triple Check pattern, since all of the slipped stitches end up invisible inside the work.
The Triple W variant below is actually the stitch we discovered first (originally we called it “The W”), but it makes more sense as a variant of the Triple Check. The stitch pattern is pretty much the same as for Triple Check but twice as wide, with pieces of 2×2 rib followed by four slipped stitches.
Triple Check and Triple W are good stitches for stash-busting projects that use up your random yarn scraps and leftovers, because you can change colors gradually as you knit. For a gradient/morphing look, change just one of the three colors at a time, leaving two of the colors alone for a while before changing again. Here’s a Triple W scarf-in-progress with a color-morphing rainbow look:
Again, if you’ve seen the Triple Check or the Triple W stitches before, then please let me know! These stitches are so simple that I feel like they have to exist somewhere, but I haven’t been able to find them. Or, maybe we found a piece of low-hanging fruit that everyone else somehow missed, stumbling on that rare combination of easy, interesting, and new? In any case, happy multicolor reversible multitask-knitting :)