Dec 22, 2015

More Holiday 3D Printing - The Snowflake

The holidays are a great time for gift giving, and if you have a 3D Printer, nothing is more fun (exaggeration warning) than 3D Printing a gift for someone you love (or just like a little). My previous post which featured the Christmas Tree ornament/decoration was a simple way to start - and then I then posted the Snowman design which followed the same pattern. This new design - the Snowflake - has a slightly more interesting base design with circular symmetry and offered an opportunity to change to a more complex construction model too.

The first version of the design is the simple two-part construction, but the second version creates a much fuller final product by using three parts fit together at 60 degree angles rather than 90 degrees.

The first, too-complicated, design
but I will print this one too soon.

Design Goals

As in the previous holiday decoration designs, I was aiming here for simplicity and ease in printing as well as creating a mode symmetrical model that could eventually be constructed using 3 parts. The mostly flat parts are designed to easily fit together to form three-dimensional objects - something easy to hang on a tree or stand up on a shelf. Both Snowflake models in this post meet that objective.

Snowflake Design Overview

The snowflake took me a few tries to come up with a method that worked well. I tried drawing it with a sketch, but couldn't get it to look right. I knew I would need to use a duplicating method to get the symmetry no matter how I modeled it. I finally just used long rectangles overlapping with some shelled outlines of rectangles at the outer edges. 

This looked amazing - but was much bigger than I had hoped. I simplified that design starting from scratch, and used a simple cylinder in the middle around which the single crystal of the flake I designed could be repeated in a circular pattern. I knew I could use this basic design with both the 2-part and the 3-part final design, so I focused on getting this right first.

Snowflake Details

The tool in 123D Design to get that symmetrical circular pattern is the "Pattern" tool. Selecting "Circular Pattern" lets you repeat the single set of crystal objects in a circular pattern around the diameter of the center cylinder object - which is selected as the "Axis" of the pattern.

This tool was perfect for the job - and I could see how I could create many different designs with the same base set of objects. With the simpler and smaller crystal pattern, and repeating it 6-times around the center cylinder, I was able to get a simple, small design to try.

The final step was to create a slot in the center to allow two of these "flakes" to fit together at right angles. I simply duplicated the design, turned one 90 degrees and moved it half the distance off the other so that each would have a slot halfway down the middle. 

Note: I actually made that slot 0.3mm deeper than halfway to allow for a bit of printing imprecision, as always. The design also required that I had enough room between the crystal legs to allow the two parts to fit together.

The More Complex 3-Part Snowflake Design

I realized with this two-part design, that it could actually look much better with 3 parts fit together. I took some time to figure out how to actually accomplish this, but the math seemed straight forward. With three parts crossing at the center, there would be 6 sections, which means each would be separated by 60 degrees around the circle to create the full 360 degrees.

I accomplished this by creating center slots which, instead of cut perpendicular at 90 degrees, were cut (subtracted) at an angle of 60 degrees. The tricky part was that 3rd piece.

The first two (which are actually exactly the same) fit together nicely since they had slots cut halfway up the center on each - but the 3rd piece now needed a place to go. I achieved this by extending the center of the 3rd piece and cutting a slot which was the full length of the centers of the first two, and by cutting TWO 60 degree angles in that same slot. This allowed the 3rd part to fit over two other parts in the center.

There was one problem - at that shallower angle, the extended parts of each flake overlapped and didn't let the parts slide together. I had two options - either cut the slot through those parts too, or, make the height of the model shallower overall. I decided on the latter, reducing the height of each flake part from 2.0mm to 1.6mm - getting to that number only through experimenting until the flakes didn't overlap.

view of the center where 3 parts
come together
The image included here shows the center where the 3 parts come together, showing the angles a little more clearly - and the other image describes the differences between the parts (the first two are actually exactly the same). 

The Models

As always, here are links to the 3D Models:

Snowflake - 2-part - One part which should be printed twice to fit together (and stands on it's own or hangs from a tree quite nicely.

Snowflake - 3-part - Three parts (even though 2 of them are the same) included in this file to be printed at once. You can also hang each part as it's own decoration, or put them together to create a beautiful ornament or decoration for a shelf.

1 comment:

  1. So cute! I'll try making this on my own. Thanks.