Knex Trammel of Archimedes




About: U.B. Electrical Engineering. I enjoy building with Knex and I have been using this site for a few years now. So, subscribe if you like what I do.

Hey guys!

I'm on winter break from college and got bored so I decided to pick back up an old hobby- knex. I built what I think is the first ever knex trammel of Archimedes. It's a truly fascinating machine with practical uses as it converts circular motion into oscillating linear motion. Unfortunately my break is almost over so I can't implement it into anything other than a mesmerizing kinetic sculpture. I made this in a few hours to prove the concept out of knex. It is a lot larger than I originally planned; however, it could be reduced in size rather easily. This mechanism has been made out of Lego by JK Brickworks, which is where I got my inspiration. My hope is that someone will take my proof of concept and make something innovative out of it. If you just want to see it in action, I've embedded a video; however I also made step by step instructions, so without further ado... happy building.

Note: This uses four cut white rods (step six shows modification to avoid the use of cut pieces) and the instructions also show the use of orange brace clips which are entirely optional.


Video URL (in case embedded video is not working for you): Knex Trammel of Archimedes

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Step 1: Motor Housing

All additional instructions will be in image notes.

Step 2: The Base

Image notes.

Step 3: The Cap

This piece caps off the base and motor assembly. Image notes.

Step 4: Lower Track

The sled rides over top of this. Image notes.

Step 5: The Sled

This is the magic behind the trammel. The step after this shows instructions for using no cut pieces. Image notes.

Step 6: The Sled (No Cut Pieces)

This is the version with no cut rods, it is slightly less stable; however, it can be reinforced with a small layer of tape. Sorry these photos are so dark. Image notes.

Step 7: Upper Track

This keeps the sled in place. Image notes.

Step 8: Bracing

These are optional because...

Pro: they lock the upper track down

Con: they occasionally cause jams in the sled if the sled gets caught on them

Because the machine works both with and without these braces, it is up to you as to whether or not you want to put them on. Image notes.

Step 9: You're Done

Thanks for viewing. The hope here is that people can take the concept and do something innovative with it.




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    12 Discussions


    2 years ago

    I made a small one that almost worked but this ones awesome!

    The Knex Inventorknextremist

    Reply 2 years ago

    You're welcome! Yes, I can definitely see this being used in many other projects.


    2 years ago

    This is crazy! It doesn't seen like it would be possible to make something like this out of knex. Great job!

    2 replies

    Reply 2 years ago

    What could you make with it? Maybe you could make a ball machine element or lift with it, but I think it is good enough the way it is.


    2 years ago

    Very nice! Works smooth as silk. Impressive :)

    1 reply

    2 years ago

    This is absolutely amazing! I can see potential from this practically spilling out! Thank you so much for this inspiration!!

    1 reply