Author Archives: dan

Stool with 3D Printed Joints

One of the things that interests me about 3D Printing is using it to augment existing fabrication techniques. I’ve already done some experiments with 3D printed joints for wood structures, but I’ve wanted to try building something with structural integrity. Printed PLA isn’t the strongest material, but the idea was to utilize its compressive strength, and minimize bending forces. I also wanted to restrict myself to only making 90 degree cuts in the wood, and minimizing the number of cuts I made.

I started with the joint for where the seat would join the legs. The goal was to make the joint easy to attach to both the legs and the seat, with holes to allow for easy sinking of screws.

legjoint

The star shape creates a straight edge on a side for any 45 degree rotation. There are 3 holes in the bottom which allow for screws to be placed that go directly from seat to leg (for strength).

After printing, everything went together very quickly.

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The problem now was that the legs bowed out too much when weight was placed on the stool. To solve this I decided to attach more supports to each leg, to prevent them from bending outwards (which was threatening to break the joints).

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At this point, the only thing left to do was to add some feet and do some light finishing.

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I think I could have made the stool a bit more aesthetically pleasing, but for a first attempt I’m pretty happy. It feels solid and sturdy when you sit on it. I also managed to only make seven 90 degree cuts in the wood (4 for the dowels, 3 for the legs, 1 for the seat).

Generating models using a Genetic Algorithm and Convolution Surfaces

A wrote a genetic algorithm that generates a tree like structure. This structure can be turned into a mesh using convolution surfaces.

Given a list of control points, the GA tries to optimize 3 things:

  1. Minimize the distance from each point to the closest branch.
  2. Minimize the sum of the length of each branch segment.
  3. Minimize the angle between adjacent branches (avoid sharp turns).

The results are very interesting:

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I also tried printing the result. It took a lot of support material, but I think the result is pretty good (I had not yet cleaned all of the support material when I took the photo).

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Basic FPV and video recording on the Conscendo S

Since I purchased the Conscendo S, I’ve played around with a number of different FPV setups. At first, I took the camera/transmitter from the Eflite FPV Vapor and mounted it on the top hatch. This worked alright, but I quickly grew tired of having a range of only a few hundred feet. I upgraded to a better camera and more powerful transmitter, which worked great, except for the hacked up mount made from foam and duct tape. I found a model for a mount for my camera, and with a few changes to increase the height off the fuselage and a quick print, I had a much cleaner setup for my plane.

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Also visible in the above image is the Mobius mount. Here is a video from the first flight with the new setup:

I was unhappy with the angle of the mobius mount, so I went back to the drawing board and came up with this:

anglemount

I used a dremel to remove the old mount, and after some more printing and gluing, I have a mount with an adjustable angle.

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Dowel structure with 3D printed connectors

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This structure is about 10 feet tall, has 60 3D-printed connectors, and 168 wooden dowels. The connectors took somewhere between 150 and 200 hours to print on my Replicator 2 (including failed prints). Currently the dowels just press fit into the connectors, but I will probably glue them at some point. This project was inspired by my desire to use my 3D printer to build a large-scale object.

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Chains

The very first thing I printed on my Replicator 2 was one of the default models included on the SD card, a chain.

Default Model for Replicator 2

Default Model for Replicator 2

Chains are a pretty cool example of what you can easily create using a 3D printer. Trying to machine something like that would be a much more difficult task, and certainly couldn’t be done in 12 minutes.

Inspired, I made a couple of my own chains in Tinkercad.

First chain

First Chain

Printed

First Chain Printed

Second Chain

Second Chain

Second Chain Printed

Second Chain Printed

As cool as this is, there are readily available parametric chain generators written in OpenSCAD that are much more practical and powerful, so I lost interest pretty quickly.

But there is more than one type of chain, and they don’t always have to be connected during the print. Thus began my ongoing interest in snap-together 3D-printed parts.

I started with a fairly simple two-part chain built in OpenSCAD:

First snap-together parts

First snap-together parts

From there it quickly led to what I just created!

 

Chain Link in OpenSCAD

Chain Link in OpenSCAD

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