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.

1 comment:

  1. Excellent post - thank you for taking the time to document this!