Dec 23, 2015

3D Printing Chinese Characters

My son is learning Chinese as a freshman in high school. For the holidays, he wanted to give a personalized gift to a friend who is also taking Chinese - so he decided a 3D Printed version of her name in Chinese would be worth a try.

Design Goals

The goal is to create an object - basically a name tag or placard - which will stand up on a desk. In this case, my son said he wanted each character to be it's own distinct object. This was a pretty basic idea - one which we've covered mostly in a prior post about 3D printing text - using extrusions of english text.  But what if the language or characters you want to print are not available in the text objects of your 3D modeling tool?

Design approach

I decided the best bet would be to use the "tracing" method with Google Draw to trace over the characters - creating sketches of each character, then extruding them into 3D objects. This is super easy once you can get an image of the characters into Google Draw. My son did this part by changing his keyboard language to Chinese, using Pinyin to enter the words he wanted, then using a text object in Google Draw.

Once the characters were on the drawing canvas, I basically just traced over them using the Polyline tool. Then, once the whole thing was traced, and after deleting the text object, I use the "download as SVG" option to get something my 3D Modeling tool can import (Autodesk 123D and Tinkercad both support .SVG files).

The Challenge

The name we were creating - Wang May Hua (in english) - is actually three individual characters (in Chinese) - but two of them were multi-part characters with parts which were not physically connected. Here was he main challenge - and basically I referred to all the learnings in my "3D Printing Text" post to make this work.

the two part character connected using small rectangles
I decided the end product should be the individual characters - in their positive form rather than negative subtractions from a block - standing up on a base. That dictated what process to use to connect the individual parts of each character.

Making it work

To connect the individual parts of each character I placed a small rectangle connecting the parts, but offset it 2mm lower than the surface of the characters so that it was less obvious.

To make the characters stand up, I added a base that stood out in front of the characters - about double the thickness of the characters - so my 5mm thick characters had a 10mm thick base, which when stood up would only be 3mm high.

The result came out quite nice - and while I started with objects which are only about 30mm x 30mm, my son is hoping we can "print these now around 10 times that size!". I guess that's a good sign.

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.

The 3D Printed Snowman Ornament

The positive results on the Christmas Tree decoration design inspired me to create additional holiday decoration models. The natural next step in designs which are vertically symmetrical seemed to be a snowman for sure. I experimented with it in the prior post - so this time I'll describe the whole 3D Snowman model.

Design Goals

I was aiming here for simplicity and ease in printing as well as just extending the simple design I already proved in the prior christmas tree model. That is, two mostly flat parts designed to easily fit together to form a three-dimensional look, and something easy to hang on a tree or stand up on a shelf.

Snowman Design

tiny version with filled parts
The Snowman is simple - just 3 circles, reduced in size from bottom to top and put together at their tangents. I added a top hat for design detail, a hanging loop above the hat and a small tab at the base so that it can fit into a stand. The stand didn't have to be designed, as I just re-used the one from the prior Christmas Tree design.

The first version had filled-in circles, but in the final design, I hollowed out each circle to make it lighter and slightly more elegant (who am I to judge)... Ok, I really did that to make it print super fast ;)

To hollow out the circles, I used the "Shell" tool in 123D, but there are two tricks: 

First, to get a thick enough shell, you might have to initially thicken the height of the object, as the modeling tool won't let you have a shell width that is greater than the height of the object (since it is also trying to shell the bottom). 

Second, once you have the shell, to get rid of the bottom layer, you simply select that inner bottom face and "Pull" (actually, Push) that face in the negative direction beyond it's thickness and it will simply disappear.

The Model

Here is a link to the the model:

The Snowman - Three parts in total - two snowman parts and a stand.

Dec 13, 2015

3D Printed Holiday Decorations & Ornaments

There's something about the holidays that inspires me to make stuff. Maybe it's just another good excuse which comes with a theme and a reason to create things.

What is that reason, you ask? Uh... because we really need more useless holiday decorations and tree ornaments.

On a whim, I started drawing a simple tree in Autodesk 123D Design - and while I had very low expectations, the resulting model and basic idea that came out really was quite nice!

Design Goal

I was looking mostly to create a flat ornament - something that could be hung from a wreath or a tree.

Within the first couple of minutes, once I had the basic shape down, I realized I could create two flat models and put them together at 90 degrees to create more of a 3D model - similar to something you could make out of cardboard.

It seemed also very feasible to create something that could stand on its own, so I also decided that this design should have a stand or something at the base that would allow it to be stood on a mantle or desk.


It was quite simple to sketch the basic tree. Using a common "stacked triangle" design, I did this with straight lines, freehand with the polyline tool, and sketched half the tree. Once that was done, I extruded it 2mm, duplicated that shape and flipped it 180 degrees and put the two halves close together (not touching) to form the tree.

The gap between the two halves would be how I would fit two of these full tree objects together at 90 degrees to make a more 3Dimensional object in the end. I connected the top half of the tree halves with a simple 2mm high rectangle.

Then I duplicated the whole tree shape with the rectangle, but in this duplicate, I shifted the rectangle to the bottom half so that this would exactly compliment the first object when the two were fit together at a right angle. The gap left between the tree halves was 2.7mm, which gave 0.7mm of clearance over the 2mm thickness of the objects to allow for printing imperfections.

I created a simple loop at the top using a 2mm high cylinder of 4mm diameter and removed a 2mm cylinder from the center to make the hole from which the ornament could be hung.

Adjustments to the model

I made one simple adjustment to make the model print faster and to give it a lighter design which would allow for more crafty decorations to be added (say string, garland, maybe even 3D Doodling in multi-color). I made all the triangle shaped branches hollow, so the whole tree was more of an outline rather than a solid shape. I liked this adjustment more than the original and kept it.

The Tree Stand

I really wanted a final object which could stand on its own - so I created a small tree stand about 32mm in diameter - using a cut off section of a sphere. I removed material in an "X" shape to hold both halves of the tree bottom.

I decided to plan for the future and leave small holes in the bottom of the tree stand and a wire channel along the bottom so that I could eventually add tree lights if I found the ambition for that ;)

Expanding The Idea

The same basic design also worked with a snowman - created with three circles and a top-hat ;) I only printed that one in a tiny size to test it so far, but you can be sure that this will lead to many more expansions and adjustments.

The Model

Get the model of this Tree at this link - and be sure to comment here if you have any ideas for improvement!

Dec 11, 2015

Creative Building with 3D Bot Bits

I've done lots of experimenting with connecting parts for both functional and fun purposes. The fun creative-building goal is admittedly more fun sometimes - and this latest experiment seems to have finally produced a reliable, creativity-inducing design that I'll keep enhancing.

I call these "3D Bot Bits", since most of the resulting creations are robot-looking.

Design Goals

There were a few things I knew I wanted to achieve in this design:

1 - Give the joints as much range of motion as possible

2 - Make the joints tight enough to have friction to hold specific positions (not collapse with gravity)

3 - Allow the joints to flex a bit without breaking

4 - Allow for customization - so new parts could easily be designed and added to kits

Basic Design Principle

The premise of this design is a simple ball-joint. One side is a round ball, and the other is a socket with the inside diameter just big enough to firmly hold the ball, with enough clearance to let it move around.

While it's pretty easy to make these two parts, what added to the challenge was making them in a way that gave them a flat enough base to print reliably (I don't like using rafts and supports) and let them snap together and apart without too much effort.

Detailed Design Process

With these design goals and principles in mind, here's a general description of how I went about the modeling:

1 - Created a sphere of around 10mm radius then duplicated it and scaled up the duplicate to a 12mm radius. The smaller sphere is now inside and centered with the larger sphere.

2 - Flattened both spheres by taking away approximately 4mm from the bottom and 4mm from the top (to make them more like bulging puck shapes).

3 - Subtract the smaller sphere from the larger, so that the larger sphere becomes a shell.

4 - Create some gap between the outer surface of the inner smaller sphere and the inner surface of the outer shell - I used about 0.3mm radius here by pushing the inner surface of the outer shell to be bigger, but you could also just scale the X/Y of the outer shell object too.

5 - Create a break in that outer shell object so that it can stretch to allow the inner sphere to be snapped in and snapped out in the finished object.

6 - Add a connector "axel" between the parts which is 1-2mm smaller than that break in the outer shell so that it fits into the break easily for connecting parts.

Strength and Stretch

The position of the part during printing is actually quite important - which is why I designed it this way. The part that grabs onto the ball - the "Gripper" - is where most of the stress will be. As the ball is snapped in and out when the parts are put together and taken apart, the Gripper will stretch. If that stretch was done along the Z-axis part of the built part (the up-and-down axis), the prt would break quite quickly given that is the weakest part of 3D Printed parts. But with the Gripper part printed laying down, it makes it much stronger and actually allows it to flex quite a bit without breaking.

A Custom Bot Bit: Robot Hand

Customizing Bot Bits

Once I had a simple ball and gripper pair working well, I started creating some alternative parts with different configurations and shapes.

One technique I use when building models like this is to never permanently merge the component parts of an object - or to keep copies of the component parts so they can be re-used.

This made it super simple to make new connecting Bot Bits which were shaped like a "T" or with two grippers on either end, or an "X" shape to allow more complex builds.

Since my initial creations looked like Robots (hence the name Bot Bits), I decided to make some super-custom parts too - like hands and sneakers and face parts. This is where I see the most interesting potential of this design - allowing others to create their own Bits to make specific types of Bots.

The Bot Bit Kit

With a good feeling about the most simple "complete" robot that can be built with these Bot Bits, I created a simple Bot Bit Kit - which contains all the parts needed to make the basic Bot. This can be printed in one shot on my Lulzbot TAZ4 in 2.5 hours very reliably.

The basic parts in this kit can also be put together in different ways to make many other creatures or designs - take a look at the pictures at the end of this post for some ideas.

Here is a link to the Bot Bit Kit model. If you print it, please comment back here with some pictures of the creation you made with this kit!

Nov 29, 2015

3D Printed "House of Cards" Stackers

With all the travel I do, I have lots of leftover hotel room keys - the credit card looking type.
I thought it would be fun to design a 3D printed connector which let my kids build stuff using those cards - basically, a house of cards which doesn't fall when you breathe on it ;)

Design Testing First

I started with the simplest, but most important part of the design - the holder which connects to the card.

This is basically a simple slot - a gap between two plastic parts which needed to be just the right tightness to hold the card firmly, while not being too tight or so narrow that the 3D printer has a hard time leaving the space during the printing process.

The simplest test part was step 1 - just creating a block with different sized gaps along the z-axis (vertically upward from the print bed). I didn't bother trying to create gaps on the horizontal plane, assuming that the slightest sag in the filament during printing would fill the gap and make it useless.

Tweaking the design to actually work

After a bit of experimentation, it seemed my Polar3D provided a firm hold on a card with a 1.0mm gap. On my LulzBot TAZ4, the gap was slightly smaller but also didn't give me as consistent a fit with the squashed first layer closing the gap too often. I could have fixed this with re-calibration I assume, but didn't try.

Once I had a simple block that worked, I tried out a few on some key cards, and found that they were simply too easily popped off as I was building. I adjusted the design as a solution to this - basically putting two blocks at opposite ends of a stick with the gaps facing inward so the holder fit over the card like a strap. This worked incredibly well.

Final design and Printing

Once I had that basic "strap" design working, I added an whole set of additional gripper slots facing in all 4 directions as well as on top of the end blocks. This combination proved to be the best and I stopped there and printed a dozen or so of these to test the building.

Building Fun!

I was able to easily build a single column square block of cards about 8 cards high which was very sturdy. The card-grippers print very quickly, as they are made of very little material - probably taking about 8 minutes each at a resolution of 0.2mm. I have yet to break one either since most of the connectors are along the horizontal plane, giving it more strength.

The Model

I've uploaded the basic model to PinShape so
you can try these yourself. It's actually really fun to try printing them in different configurations to meet the specific needs of a house of cards you want to design.

Nov 25, 2015

3D Printed Phone Rack - charge and organize 5 or 10 phones

If you ever find yourself needing to organize, carry and charge 5 or 10 phones at one time, I've designed a solution that might work.

My motivation was to have a quick alternative solution for the Google Expeditions project - where anywhere between 5 to 30 phones along with Google Cardboards are used in a Classroom to take kids on virtual field trips. The logistics of carrying and charging that many phones is harder than it might seem.

Design Goals

I started with a goal of designing a holder for 5 phones. My goals in this design were:
> keep the phones from banging into each other
> make it easy to insert and remove the phones
> have a method to keep the phones in place during transit
> expose the usb/power port for easy charging
> have a handle to carry the phones
> have room for air circulation to avoid over heating
> work with Nexus 5 phones to start (later Asus ZenPhone)

I originally started thinking of a design which would allow for expansion - allowing multiple holding racks to be connected into larger racks, but soon realized that I should focus on getting a solid design done and later figure out that feature.

Starting the Design

With the Nexus 5 phone dimensions taken - I created a simple rectangular box with 2mm of added material on all sides. I decided that the holder should allow for about one-third of the phone to stick out, so it is easy to grab to remove - so I reduced the height of the rectangle by 1/3 (about 25mm).

I then hollowed it out using the 123D Design tool called "Shell" (under the "Modify" tools) and asked for a 2.10mm shell width (I like to use even multipliers of my 0.35mm 3D Printer nozzle diameter). I then thought about how to put multiple of these shapes together to form an array of 5 holders as a single object.

Expanding and Giving Breathing room

Having 5 of these alongside each other in my modeling tool (123D Design), I could clearly see that I should almost completely remove the inner walls between phones so that there was plenty of airflow and much less material needed in the print. I left about 5mm of separator wall on the bottom between each phone and about 10mm of separator at each end. This would form slots which each phone would easily slip in and out of.

The outer walls were still solid, and I wanted to give more airflow there and reduce the material needed. This is where I had my most difficult challenge in actual printing.

I created several "holes" through the outer walls, with rounded tops to allow for better printing without supports. When printed, the "stanchions" which formed between those holes kept printing too weak and breaking during prints.

This kept happening almost regardless of how thick I made them. I experimented several times, and lots of fails and broken 10-hour prints later, I discovered a hole design which didn't produce the problematic stanchions - triangular holes (see pictures later in post).

Practical adjustments

With the 5 holders together now in what looked like a "rack", there were 3 important adjustments.

Avoiding Errant Button Pressing: The side of the phones contain power and/or volume buttons, and with the phone on its side, I did not want the buttons being pressed by the weight against the holder. To avoid this, I cut holes along the bottom of every phone slot, leaving plenty of material to hold the phone, but with enough of a hole to allow the buttons to never hit anything and press by mistake.

Room for Charging Cable: With the phone on its side, the charging port at the end needed to be accessible, so I cut simple grooves about 12mm deep into both sides, so the phone charging cable could be inserted from either end.

Handle and Phone "Seatbelt" :  I knew I'd need a way to carry this thing - a handle of sorts - and a way to secure the phones in their slots so they wouldn't dump out if it tipped over. I created simple handles on each side which would be used for either an elastic strap (seatbelt) and for a Grip that I would design.

The Grip (Handle):

With the handle holds on either side of the phone rack, I designed a simple handle that would be printed on it's side so that it had better strength (things printed along the x and y axis of the printer are stronger than things printed in layers up the z-axis). It needed two hooks to grab onto the handle holds and it needed both a cross bar to hold the phones and a grip for a person to carry it by. I decided to use the slight flexibility in the final PLA plastic part to my favor - so that the handle has to be stretched slightly to fit it into the holds, which would avoid it coming loose while carrying.

From 5 to 10 phones - and Nexus 5 to Asus ZenPhone

With the 5 phone holder finally printing successfully, I decided (with a strong push from my friend who is running the Google Expeditions Pioneer program) to try a 10-phone holder. It was not too hard to cut up my 5-phone model to extract and then duplicate one of the inside phone slots another 5 times. The harder part was stretching the model to hold a bigger phone - the Asus ZenPhone.

Once I had the new measurements, I realized that it would be easier to start the model again with a single phone slot and then duplicate it 9 more times. I eventually got this right - and while it's too hard to describe in words, perhaps I'll make a video of that process eventually. The challenge was more one of measurement discipline than the rote work of adjusting the design. It took 3 tries to get right, as I first forgot to adjust the length of the phone slot, then I forgot to adjust the height of the handle to accept a wider phone.

Final Product

I finally got this right, and after a 13 hour, 50 minute print on my Lulzbot TAZ4, I had a great 5 phone holder. I simultaneously printed the handle on my Polar3D - and the two parts fit happily ever after :)

I got a chance to test my phone holder in the field at the edcampNJ event on November 21, where we demonstrated Google Expeditions for about 100 teachers! The phone holders (both the 5 and 10 phone versions) worked flawlessley.

The one weakness I'm seeing in this design are the separator parts between phones where the charging cables come in - they are weak and starting to give. I expect they will all eventually break off, but I also don't think they are completely necessary to the design. Always looking to improve, I'll tweak that in the next version.