Modular Just Got More Modular

People can actually 3D print keys, so I can’t show mine here. Sorry.

I’ve had this giant modular desk and cabinet set in my room ever since I was 12 or so. The walls and dividers are lined with rows of holes so you can choose what goes where.

I realized there’s a lot of vertical space along these walls, and then it hit me: I can 3D print fixtures and stick them in the spare mounting holes! The first thing I did was to make a key hook so I would know where my keys are.


Measurement and Design

I measured the holes to be about 0.195″ (~5.0 mm) in diameter and 1.266″ (~32) mm apart, then drafted up some test anchors at these dimensions to see how close the 3D printer could get. Unfortunately my cheap caliper is in inches while my 3D prints are in mm.

Great, now how do I get this out?

I printed single pegs to test the fit and found the required diameter to be 0.190″ (~4.8 mm) in order to fit snugly. I then printed a 2-peg wide piece to get the spacing and found my original measurement of 1.266″ was correct.


This works.

I designed the anchor and hook separately so that I could avoid having to print suspended material. Printing them as one piece would definitely create large overhangs that probably wouldn’t be possible for my printer to overcome. I designed them so that there would be a way to lay them flat so that there’d be no material suspended in thin air.

The ancient Egyptians built the Pyramids with the widest parts at the bottom. Imagine if they tried building them upside down! That’s why I wanted to avoid overhangs.


Printing

They're hi-fiving each other.

They’re hi-fiving each other.

I found that when printing a lone peg, the dimensions were generally intact. However, when printing more than one, the printer left strands of excess plastic as it completed a layer of one and moved to the next. These strands eventually formed into branches that adversely affect the dimensional accuracy.

On the anchor, the external feature dimensions such as the peg length, diameter, and the base width were accurate to 0.1 mm or less, but the inside hole measured 0.5 mm too narrow on all sides. This was the largest error I had seen so far and was quite surprising given that everything else was pretty good. Even that cube puzzle I printed earlier had interlocking pieces in several directions and they still all fit together.

I decided to address this by reducing the thickness of the hook that would attach to it. I needed to conduct more tests on internal cutouts and see what the errors are caused by, so for the time being I made the hook a little thinner to compensate. That’s the beauty of 3D printing: I can just change a number and print it again!


Mounting

So modular, I've already moved it!

So modular, I’ve already moved it compared to the opening picture!

The pieces locked together easily and they’re pretty rigid for 3D printed parts. The assembly slid into the mounting holes with ease and now I have a cool new key hook that takes advantage of space I couldn’t use before! Next I’m planning to make a shelf, which will be challenging because the spacing across the columns of mounting holes is wider than my print volume (6″ max).

Here’s the link to my model files if you want to check them out. Stay tuned for more random things straight from my 3D printer!


 

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