Monday, November 17, 2014

Release Notes: FlexMesh 2.1 Snap Together Flexible Chainmail Mesh

FlexMesh Dodecahedron – Bob Krause

FlexMesh is a set of compact 3D shapes that can snap together to create colorful, flexible and possibly very large 3D printed objects. FlexMesh 1.0 was released on Thingiverse this past August. This initial version was an exercise Cole, an instructor at a3D modeling camp I ran last summer, and I worked on to demonstrate ways we might overcome some of the limits of 3D printing today. The flexibility of FlexMesh 1.0 objects came from the use of pins. But I found that these pins and the slots they slide into are somewhat cumbersome to design and build with.
FlexMesh 2.0 was released last month and immediately became a featured design on the Thingiverse home page. FlexMesh 2.0 is much easier to work with and offers greater versatility. The pins have given way to nubs that snap into holes to form hinge-like joints that connected pieces can pivot around. Many interesting, colorful and large objects have already been built using FlexMesh 2.0 -- with more designs on the way.

This post contains the release notes for FlexMesh 2.1. If what you've read so far about FlexMesh doesn't interest you, then you might want to turn your attention elsewhere. But if you're interested in learning details about FlexMesh 2.1, then please read on.

If you have any experience playing with the 2.0 kit then you've likely noticed that it can sometimes be hard to snap pieces together, while other times you find that the fit of connectors to be so loose that some pieces come apart too readily. This becomes a real problem when you drop a bucket of FlexMesh in the center of a group of kids because they either can't snap the pieces together or become frustrated that their Minecraft creature keeps falling apart.

Octahedron – Bob Krause 
Getting The Best Connection

Experienced has shown that there's so much variability of printed pieces using different printer/material/slicer combinations that there's no single connector design that prints well in all situations. So the 2.1 release includes no fewer than 10 slightly different variations of connectors. The difference in each is the space between the nubs. The nubs of the shape named FlexMesh2.1Sub0.stl are the closest together, while the shape with the nubs furthest apart is FlexMesh2.1Sub9.stl. For reference, the shape named FlexMesh2.1Sub5.stl is pretty equivalent to FlexMesh2Sub.stl, and FlexMesh2.1Sub9 is the same as FlexMesh2SubWide.stl.

If you were happy with FlexMesh 2.0 connectors? Then just use the #5 sub shape in version 2.1. Otherwise do some test prints of various Sub shapes to find the one that works best for you.

Note: Here's how to distinguish which printed connector variation you're holding... The SubWide shape has a subtle 'W' on top. Each of the Sub's released in the 2.1 release has a number embossed on one side between nubs. If you don't see either of these markings then you probably have an original Sub.

Important: For best results, be aware of the printer, filament and slicer combination you use for fabricating each batch of Subs and Mains. Take written notes if you think that'll help. Which spool of filament you use seems to be the greatest factor. PLA produces pieces that are ever so slightly smaller than ABS. "Chewy" ABS filaments are less predictable than that of higher quality spools.

Grand Monopoly – Bob Krause 
A Consistent Length For Each Side
Perhaps the greatest flaw in the 2.0 design is that the length of 3-sided shapes, Tri's, and 4-sided Quads is different. This creates a noticeable bulge in objects built using both shapes because the Tri pieces stick out further than Quads.

This inconsistency has been corrected in FlexMesh 2.1. But doing so requires that the side length of 2.1 Tri's and Quad's be different than their 2.0 counterparts. Quads are 1mm wider, while Tri's are about 0.5mm thinner. Not to worry, FlexMesh 2.0 and 2.1 are still fairly compatible for most simple projects. That's why the version 2.1 is being released as an update to what was the original FlexMesh 2.0 Thingiverse design.

Cuboctahedron – Bob Krause
Filleted Inner Edges Of Main's
Some people have had problems with "blooming" of the first layer of printed FlexMesh pieces. As any 3D printing tutorial points out, the first layer of a print is the most important determinant of the success or failure of the print job. It's important that the filament laid down for the first layer be pressed down firmly on the build platform so that the piece adheres through to job completion. Bloom is the effect that occurs when the outer bead of material is pushed so far outwardly so as to deform the overall shape of that initial layer of the piece. This was identified as an issue for the inner edge of Main shapes because it can cause the full rotational range of connected Sub's to be reduced to the point that two adjacent Main pieces can't rotate the full 180 degrees.

This problem has been addressed in FlexMesh 2.1 by adding a fillet to this inner edge. Of course, the fillet was added to both top and bottom edges.

New Shapes
FlexMesh 2.1 includes new 5-sided Penta and 6-sided Hexa Main shapes, which have the same side lengths and filleted inner edges as the updated Tri and Quad shapes.

Cuboctahedron – Bob Krause
A New Shape Family
An entirely new family of FlexMesh Main shapes have been added as part of FlexMesh 2.1. These shapes, which can accept as few as 2 to as many as 6 connectors, are more rounded than those in the original family. Unlike the original family of Mains, the diameter of each rounded shape increases with the number of connectors it accepts. This lack of a standard side length makes sense as the new round shapes don't have sides. The profiles of rounded shapes are very different than the originals when both are viewed from above. Because of these differences, objects built using rounded shapes also have a different appearance. Some connection patterns result in a wide gap between pieces align in one direction. Other patterns result in fairly tight fits between Mains.

Print a batch of rounded pieces to play with. Early users of these shapes have found the 2-sided Duo to be a particularly interesting and useful element to build off of.

Note: People who've printed the rounded family of shapes report that platform adhesion of Duo pieces is more of a challenge than is the case with other FlexMesh shapes. To optimize success for printing Duo's be sure that the build platform is "fresh" and level, and that nozzle clearance is properly calibrated.

Duo Band – Bob Krause
Comments & Questions
The best place to submit FlexMesh 2.x comments or questions is here on Thingiverse.

Saturday, November 15, 2014

Tinkercad Alternatives?

Rascal The Dog – Lucie

A question was recently raised about whether there are any alternatives to Tinkercad as a classroom 3D modeling tool. This is a very good question.

The reality is that Tinkercad currently occupies a “footprint” in the market for 3D modeling software that addresses a significant piece of the requirements of makers, teachers and students. If Tinkercad weren’t available, didn’t occupy this footprint, then I’m quite certain that there would be some other product in the market today. Mind you, I don’t believe that Tinkercad’s presence entirely precludes competitive products, but the space that Tinkercad takes up incrementally reduces the size of the opportunity left for others in the market.

In my view, the key traits that make Tinkercad stand out as a uniquely well suited solution for makers and educators are:
  • Shapes add volume, holes subtract volume
  • The ability to group and ungroup shapes, holes and groups
  • An approachable stylesheet with minimal noise (Translated: a good look without too much information that confuses users)
  • A means to programmatically design and configure shapes (Though the current Shape Generator tool is fatally flawed in so many ways.)
The biggest hole in Tinkercad's current feature set is the inability to parametrically define and relate shapes.

I’m always on the lookout for applications to bring into classrooms as full or even partial replacements for Tinkercad. I’ve yet to find a viable alternative. All the other “mainstream” modeling applications are too noisy, don't support "ungrouping" or offer metaphors inappropriate for young students new to 3D modeling.

I’m sure Autodesk doesn’t want to hear this, but I think everyone would benefit from some real competition in these maker and educational markets. — Tinkercad included.

Wednesday, November 12, 2014


Tinkercad Is Down – Autodesk

This morning the following letter was sent to Autodesk CEO Carl Bass, CTO Jeff Kowalski and several leaders of the 123D applications teams who are responsible for the Tinkercad product and engineering efforts. Tinkercad is a central component in the toolchain of schools' 3D modeling and printing curriculum. I encourage everybody with an opinion about the state of the site to constructively discuss your requirements and expectations and the impact the disruptions have had on your classrooms and your long-term planning for 3D curriculum.

Voice your support for Autodesk improving Tinkercad reliability, responsiveness and feature set by using the #FixTinkercad Twitter hashtag.

I was a Tinkercad user a year or so before Autodesk picked up stewardship of the site in the spring of 2013. I’ve been an active user in my own work and as a 3D modeling instructor at various schools in the East Bay. Guillermo (Melantoni, 123D project Line Manager), I’ve brought you into my classrooms and into my lab early on to show you how my students are using the tool. I’ve been to your offices several times to meet with both product and engineering teams to discuss the product’s many strength and crippling weaknesses. 

It was around this time last year that the state of the site had deteriorated to such an extent that I publicly called out the Autodesk team proclaiming, Tinkercad is Dead, because the site was at that point for all intents and purposes completely unusable. I was a lone voice in that discussion because few teachers were using the site as centrally in their curriculum as I was. Sure enough, fully 2/3 of my students who were affected by those failures chose alternative activities and never returned to 3D modeling. It’s been relayed to me that however opinionated I was, this frank online discussion contributed to Autodesk committing some additional resources and to the decision to make some changes in the development team. This eventually led to the migration of the application stack over to a large public cloud. Responsiveness improved markedly in the spring as a result, though many significant usability issues have still never been addressed.

Now, 10 months later and smack in the middle of another academic semester in which 100’s, if not 1,000's, of classrooms are now reliant on the site as a central tool of their current curriculum, the site has once again been left completely unreliable for going on 3 weeks with no end of the troubles in sight. The students, teachers and districts now left to cobbler together replacement curriculum in real time are the same stakeholders Autodesk has actively pitched Tinkercad to during the past year as an ideal tool for classroom use. Many are us are Tinkercad users because Autodesk encouraged us to do so. 

If one were to not read user complaints and only focus on the hype and spin emanating from the 123D team that Tinkercad is managed by, it might sound like the site is virtually flawless and that users are all but dancing in the streets. Yet it’s my sense and the sense of other teachers and administrators I’ve talked to, that Autodesk doesn’t fully appreciate the full extent of people’s frustration with Autodesk’s stewardship of the site. Stating the obvious, a web application is a fundamentally different animal than a native application. Autodesk may not fully appreciate the significance of these differences or the reasonable expectations and requirements schools have for the site even though they don’t currently pay for students' use of the tool. 

I also don’t think Autodesk realizes the negative impact users' Tinkercad experiences are having on the company’s long-term objectives at the intersection of the maker and education markets and their impact on Autodesk's brand overall. Though I appreciate Autodesk’s strategy for expanding your presence in these markets, I think it prudent that you reassess your execution and adjust your tactical plan to take into account the impact ongoing conditions will have on your long-term prospects. As an aspiring stakeholder in these communities, I would also ask you to consider the impact your missteps are having on the makers, students and schools you serve. 

- Bob Krause
Berkeley, CA