An interesting application for 3D printing is in the presentation of architectural models, either to show multiple proposed options, or as an intuitive way to present a design so the viewer can get a sense of scale and overall feel of the building. To show this I modeled the floors of a residental suburban house in seperate pieces. The roof can be removed to reveal floor two. Floor two can be removed to reveal floor one, and so on.
I would like to get more furnishings modeled into it, but for a first go, I’m happy with it. Things like kitchen cabinetry and garage items will help the model feel to scale more. The window and door details are minor, but help get a sense of scale.
Providing a way to align the levels would also be essential in a final scale model. Perhaps magnets would work, but physical pins might be simpler. In this location I have a section of wall that does not line up from first to second floor. It was an issue in the modeling, fixed in software.
The structure is also missing the stairs, the front porch, the basement, and the back deck. All of which could be added to improve the sense of scale.
The idea to design a print in place hinge is one I had in college. I wanted to create a protective case for an external hard drive that also has the mounting holes for my Raspberry Pi 3+. Figuring out the mounting holes for the PI was simple. The dimensions are clearly posted online so I first made a simple support piece with holes and space for zip-ties to hold the PI in place.
The intention was to use the PI and drive combo as a portable media center where a library of tv shows and movies can be easily hooked up with simply a power outlet and an HDMI cord. Since the initial idea was had, I have built and maintained a 12TB NAS storage server which hosts a Plex server with so much more media than I ever could have fit onto a single drive. With just an internet connection, any smart device can access the full library; clearly a better solution.
My first attempt at a P-I-P hinge was at the same time as an interest in printing basic geometric shapes. It was a simple container made of two halves of an isosohedron with a single hinge segment connecting the two. Interestingly, the filament ran out half way through the print so it happens to be two toned.
Shockingly, my first attempt at a P-I-P hinge was successful! I forget the specific tolerances of the hinge mechanism, but I do know it ended up pretty loose. I think I used around 1/16″ of tolerances all around (see below for more information on tolerances). It also doesn’t help at all that there was only one hinge section. With future designs I made sure to use multiple hinge segments.
I wanted the part to be special in that it could only be created using 3D printing. The pin of the hinge has a curve in profile view, making the pin narrower at the middle and wider near the ends. The outer part of the hinge used the matching curve, with some tolerance.
image of profile view wireframe of hinge
I figured that the pin of the hinge doesn’t technically need to be a cylinder, and that perhaps having the pin wider at the base and narrower down the middle would be better for supporting the thin plastic. Traditional manufacturing methods would not permit an axle being built like this as it would be practically impossible to assemble.
Future designs of P-I-P hinges don’t include this kind of complexity, though I did produce a working prototype of an external hard drive case that does. It uses four hinge units along the long side of the case. The bottom section only holds the drive with a hole for a USB connection. The top is trickier, with some raised sections designed to hold the PI support piece (seen above) and more space designed to hold SD cards or other devices.
image of ehd case
As mentioned, the hinge geometry is like the isosohedron design I used. The pins narrow near the middle. With four hinge sections, the action of the hinge actually is quite satisfying.
image of open hinge, hinge details
This was the longest print I had done to date. I had to leave it overnight at school, but I’m not sure the actual print time on it. When I noticed the layer shift in the print the next morning I was worried it would affect the hinge. To my surprise the hinge still worked. Unfortunately, the box no longer closed properly. The layer shift effect was doubled thanks to the design.
image of layer shift profile
A few years have passed since that point. I have left the convienence of college 3D printers and now am constantly looking for projects to do on my AnkerMake M5 printer. With that I needed software other than the free college accounts I had been using at that point. Near the end of 2022 I purchased a persistant liscence to Rhino 3D. Rhino includes many helpful features, one of which is the visual programming language known as Grasshopper 3D.
Image showing Rhino and Grasshopper
Below is my program to produce custom sized P-I-P hinges. There are special settings to specify the overall tolerance amount, number of hinge segments, and more.
I find that 0.4mm of tolerance between all surfaces is plenty good enough for standard applications. I initially tried this as it is the nozzle diameter of the printer I use, as well as most of the printers I used at school. 0.4mm seems to me to be the standard residental printer resolution. With a more precise printer, and maybe some layer settings, slicing tolerance for example, the tolerance might be able to be brought down. Naturally, lower tolerances should create tighter fitting hinges.
I’ve always been interested in a very specific chess set. It is the set shown in the intro video to the game Age of Empires 2: Age of Kings.
The set, known as Lewis chessmen, is a unique set of pieces. The main pieces (all but the pawns) are especially humanoid.
image of Lewis chessmen
I intend print out a set of pieces in the Lewis chessman model.
Note that the Knight is not finshed yet. This has yet to be printed.
Pawn
Rook
Knight
Bishop
Queen
King
Something that I would like to integrate into the design is some sort of chamber inside the base of the pieces that can be filled to provide weight.
If I can make easily printed threads, I can create a plug to hold heavy fill material to get these to a better weight, with the weight located in the base. It would be nice to write a Grasshopper definition to do just that.
For fill material I’m thinking sand, small ball bearings, or some combination of both. Ball bearings might be easy to feel, when they roll around inside, but if they can fill the volume of the space they would be pretty stable. Sand might also feel strange, and sound like a maraca if there is space. In either case, limiting empty space is the key.
Professional chess sets have specific weights and tolerances for each piece. I think. After looking into FIDE handbook, there is no note of the weight of pieces. The height is defined, but not the weight.
After plugging the space, we must secure the bottom of the piece. The simplest thing to do is to add a circle of felt.
After finalizing my P-I-P hinge program in Grasshopper 3D, I had been looking for good projects to use it on. There never seem to be enough good barbell collars in the gym so I began wondering if I were able to prototype one.
The design for my 3D printed barbell collar is nothing revolutionary. It is essentially the same as other cheap collars.
Generic Barbell Collar
My 3D Printed Collar
Latch View of Generic Collar
Similar to other projects of mine, I aim to capitalize on the advantages of additive manufacturing. Using the same principles as my PIP hinge design, I am able to make the whole assembly from one print; a part count of one. From a manufacturing perspective, minimizing part count is a great way to cut costs of finished goods. My design requires no assembly, just a bit of support removal.
Getting to this first working prototype wasn’t as simple as it should have been. To start, I wanted to be sure my hinge design on the back of the collar would work. My PIP hinge generator worked very well first try.
From there I had to design the latching mechanism. I using the same tolerances as the hinge for my first print. I ended up with a single complex piece, an offset shaft that kind of reminds me of a crankshaft. The tolerances worked well, but I did the latch incorrectly. It didn’t open fully or easily.
Closed Latch
Open Latch
I put the latch clip on the short piece of the mechanism. I should have put it on the large piece for better mechanical advantage. The latch action is incorrect and will not work.
One of my favorite theoretical shapes is the möbius strip. Named after August Ferdinand Möbius who, concurrently with Johann Benedict Listing, discovered the shape.
A continuous closed surface with only one side; formed from a rectangular strip by rotating one end 180 degrees and joining it with the other end.
Princeton University
I really like mobius strips due to their simplicity. The geometry can be pretty quickly created in Grasshopper, within Rhino 3D. I wrote a script that allows me to get a slicable .stl file in minutes.
I have 3D printed a couple of mobius strips. Below is the largest.
For college I made a mobius fidget spinner, as an exercise to use the 3D printers. We had to create a spinner using the three nuts seen inset below.
There is an unintended feature of this fidget spinner. The geometry naturally causes a really cool optical illusion. The edge rolls over in only one direction.
Grasshopper Definition
I created a Grasshopper 3D definition to produce 3D models of mobius strips. I can control by the selections below, outer radius, inner radius, thickness, and rotations. There are a few more variables that are buried in the code.
This seems to me like a great introduction to Grasshopper. My script works as follows:
Step 1
The first step is to define the overall size of the calculated Mobius strip. Here we define 3 circles, all directly on the XZ plane.
Step 2
Here is where we can set the number of rotations the strip will do.
University of Virginia Architecture
Finding interesting Grasshopper definitions is always a treat. The University of Virginia Architecture program has an awesome website sharing many definitions.
