Trammel of Archimedes - 3D Print

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Posted in Technology3D-Printing

Introduction: Trammel of Archimedes - 3D Print

About: I like to design and build random things.

This is a more advanced version of the Trammel of Archimedes I posted last week. Since this is above my woodworking skills, I took the easy road and 3D printed the design. All STP and STL files are included in the last step for you to download. Also, I bet there are woodworkers and machinists that can produce a much nicer version out of “real” materials. If anyone tries, please post pictures in the comments.

The CAD animation which is quite mesmerizing is shown here:

See the actual print version in motion here:

Step 1: Tools/Materials

Tools:

  • 3D Printer
  • Screw Driver
  • Wood file or sandpaper (depends on the quality of your printer)

Materials:

  • Screws: Pan Head, #6, ¾” Long

Step 2: Base

The base is a six sided shape (hexagon) which you might recall from school has a total of internal angles equal to 720 degrees. The 3 passes on the trammel are centered on the vertices of the hexagon. For the paths, a chose a dovetail groove. This groove was based off a lesson learned on my previous print (T-Slot) where I had to remove the supporting structure above the slot. I added rounds to the center edges which help keep the slides on track if they enter to the middle section at an angle. The pockets around the parameter are mostly cosmetic even though they do add a nice place to grab the trammel from underneath as you are spinning it. I mainly added them to reduce the weight since my printer (local library) charges $.25/gram. For reference, the entire trammel cost ~ $22.

Step 3: Slides

The slides were designed to match the grooves with a 1/32” clearance. I added chamfers and rounds on the slides to allow for cleaner movement. Note that when looking at the drawing you will see more than 1/32" of an inch clearance. The final dimensions are after the rounds. For each slide piece, the hole is centered on the top and is sized for a #6 screw.

Step 4: Handle

This took a little geometry to figure out the correct spacing of the holes. I've included my attempt to explain the the dimensions.

Step 5: Knob

Arbitrary design for the handle knob. You could also purchase one from a hardware store for the same price as a 3D print.

Step 6: Assemble

Place the three slides in the grooves. Screw the handle to the slides as shown. Attach the knob to the handle from the backside.

Step 7: Final Product

Twirl away.

Step 8: Files

All files are included to build your own. You will need to purchase screws. I've also included STP files in case you would like to modify the design.

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    24 Comments

    Hey, this seems like a really cool object, but what can you use it for?

    1 reply

    Thanks. It really doesn't have a use. The 2 pass versions are given names like "do nothing machines" or "bullsh*t grinders". See the intro from my previous version for more details - https://www.instructables.com/id/Trammel-of-Archimedes/

    hi, nice work... I made one of this some time ago... posted on thingiverse. Mine is all printed, no screws

    https://www.thingiverse.com/thing:1552846

    1 reply

    Nice job! I like how you removed the screws. I noticed in the video that we both have the same issue with grabbing the base while turning the handle which is a little awkward. If I get around to redesigning it, I plan to make it so that the slides don't extend beyond the base during rotation.

    First off, beautiful job and beautiful prints.

    Secondly, I was just curious as to how exactly the holes in the handle were calculated, given the distances they are sliding or the lengths of the sliders, or whatever info is needed to calculate such a thing.

    Thanks a ton in advance

    1 reply

    Thank you. I have to admit that I used CAD and animation to work out the first set of dimensions. However, before I finished, I did go back and check the math. I just added my calculations as a picture on step 4. Note that I stated that the first horizontal dimension (2") is arbitrary. This is correct to a certain point. Realize that the slides can't fall out of slots on the ends or collide in the middle. I'm sure there is a mathematician out there that could do a much better job explaining it.

    This is very cool, I would build it if I had a 3d printer!

    1 reply

    Thanks. I don't have a printer either. My local library offers the service.

    wow a really nice mechanical mechanism

    My guess says it is also an ellipse.

    1 reply

    Based on the animation, it looks like an oval. I think the sections in the middle are straight.

    Thanks. I had to look that up. That's way above my capabilities even though the tech is 2000+ years old.

    Ευρήκα! Cool pront, thanx for sharing!