Saturday, June 30, 2018

Dungeons & Dragons dice in wood

One of my girls asked if I could make her a set of Dungeons & Dragons dice. Not knowing anything about them, I sent her shopping on Thingiverse and she settled on this set designed by JakeVav. I printed it in Hatchbox Wood PLA hybrid so I could make it look antique-y.

No, I didn't print them all at once, this is a reunion photo. I tried to print them in groups of 2 or 3 to save setup and print time, but I found that as the extruder jumped from one die to another the filament sagged out of the nozzle and left a little "worm" on the next die. Although I experimented with retraction, coast and wipe settings, the wood filament is just more prone to this side effect. So I reprinted the last few as singletons and they came out much cleaner.

After some cleanup I treated them all with wood stain (submerged for several hours) and added a couple very thin coats of Varathane. They came out pretty darn wood-like, especially the triangular one with some color variation that looks like grain.








Here's the whole set ready to give away.
There were a few problems. Lettering can fail to come out clearly if it is too small. And there were a few "slumps" especially in the overhanging faces (I did not use any support structures).

The 10 face was down to the bed, so the 90 was an overhang. You can see the edge between 90 and 40 came out kind of ragged. But in a project like this that is supposed to look ancient and magical and mysterious, I figured a little irregularity gives it character.



Same here, the 1 was on the bed and so the 7 was an overhang.

In many cases I had to clean the letters out with a very tiny Dremel bit.












Another issue is that the faces on the bed come out glassy-smooth. I sanded them in a single direction to give them some "grain" for the stain to penetrate. The 10 and the 1 above came out pretty well. I should have sanded his 1-2-4 face more deeply - it came out more smooth and yellow than all the rest.






At first I tried to use some GP3D wood filament I have on hand that is a bit lighter in color. But I could not get it to stick to the bed, even though I was using the wonderful Magigoo coating. I was trying to print one of the smaller dice, and it was just not enough surface area to stick to the glass. I gave up on that pretty quickly and switched to the Hatchbox. This is the second project in which I've given up on the GP3D - see my trophy base project. I don't think I'll try it again.

Evil thought: (only after it was all done)  I've been using Simplify3D software for the last 7 months. One of its features is the ability to print different levels of a model with different settings. I printed this with 20% infill. But it would be very easy to print the lower layers with a much denser infill, which would essentially make them "loaded" dice. The bottom face would be much much heavier, making it slightly more likely to land on the bottom, and making the opposite face more likely to come up. So... if you're playing D&D or any other dice game with 3D-printed dice, watch out!

Friday, June 22, 2018

Multicolored folding robot

I saw this video by 3D Printing Nerd and figured I'd give it a try because I'm interested in clever techniques. A single-extruder 3D printer like mine can only print in layers upward (with a few exceptions) and so color changes are limited to horizontal layers. Picture a layer cake with chocolate on the bottom and white on top and frosting in between. I've done a few projects with multiple colors or different filaments, like this trophy base.






These folks at Fab 365 have designed robot models which are opened up into boxes, the sides joined by living hinges. After printing it all flattened out you fold the body into a box, which wraps the colored layers onto all four sides.













By carefully choosing the layers at which to change colors you can highlight parts on each side of the body with contrasts that make them "pop". I chose to do four colors in seven layers.








Other parts that stick up like the arms and legs and head also get the multiple colors, and they end up mostly vertical.

The shoulder parts, the frame on the front, and the jet pack mount on the back are all the same height, so they all get the orange color. The little green controls on the front are just a few layers thick and contrast well with the white background.

The feet and the fingers are about the same height, so they both came out blue. So did the top of the head, unintentionally I don't know if the model was actually designed with multilayer in mind... I think not because some of the arm and leg segments are not horizontal, so the colors cut across them at an angle.

This is all previewed in the slicer software to see exactly where the different features start, and each different colored layer is given its own segment. I needed to pause the print at the start of each layer. I found some G-code on line which was supposed to do that for me: pause the print, raise the head and move it to the side so no plastic will drip on the model while I change filament. It actually didn't work except after the first layer, so I had to manually pause it for each change. Later I found out how I had implemented it in the wrong place - better luck next time.  So I'm pretty amazed that I was able to get a good result in just one try! Now that I know how this works I could use it in my own designs.





The result is quite a patchwork of color. It's Robbie the Robot from the movie "Forbidden Planet"!

The living hinges were a little weak, and the "tab A into slot B" design that was supposed to hold it together were not sized right. So I used Super Glue and it all came out fine.








As a bonus, the design includes movable arms and legs. The shoulders actually each include two nested ball-and-socket joints, so the arms can raise and lower, and also rotate, giving them an impressive range of motion. (But on my print, one joint fused and can only rotate.)  I'll remember this joint idea for some of my own designs.

Wednesday, June 20, 2018

Apple device charging stand


My daughter asked me to print this charging base for Apple iPhone, Watch, and Airbuds. It's on Thingiverse and designed by Raphael Barthe.











There are some cable tracks on the bottom and they tunnel up through the stand to reach each device holder.












I chose to print the version with the watch shelf separated to be glued on later. This avoids the support issue. 





I printed it in white eSUN PLA. It came out great! The second time. The first time, the filament was crossed under itself on the spool which led to a tangle.