Hi!

Recently, I've posted a video series where I showed the whole designing process of Gear Halpern-Meier Tetrahedron. Finally, now it's built physically.

Essentially, this puzzle is very similar to Gear Pyraminx and is derived from it by moving the cutting surfaces towards the faces so that they do not intersect in one point, but outline an independent central face element, which is equivalent to central face triangle in Halpern-Meier Tetrahedron (or Jing's Pyraminx, whatever you call it). Displacement of the cutting surfaces enlarges the edge gears so their teeth number increases from 6 to 8. The corners, on the contrary, get reduced from 9 to 6 teeth. Number of teeth on the gear basement stays the same - 15.

Like in Gear Pyraminx, it's possible to turn all gears at a time keeping the same tetrahedral shape. But as opposed to Gear Pyraminx, here it's not possible to turn 3 corners in half-a-turn state, because this movement is blocked by deep interconnection of the edge gears.

Gear HMT design is much more stable than Gear Pyraminx in sense of skipping gears, because all teeth on the gear basement physically protrude up to their geometrical tips, so the Gear HMT does not have "weak teeth" like the Gear Pyraminx has in the face centers.

YouTube Video (with English subtitles)

The turning looks fantastic! Great work!

Deceptively simple puzzle, beautiful. Was this 3D printed in WSF? If so, why does it not have the normal "scratchy" sound when turning?

Amazing.
Can you post an image which shows the "turning on opposite edges"-move in midturn?
Edge length?
Weight?
How often do you have to turn one corner to restore the shape and the colors?

Andreas

Yes, it's WSF. I polish each surface manually before assembling so that turning gets smooth.
The pictures are below. In midturn of that move all edges are turned by 90 degrees.
Edge length is 76mm, weight 32g. To fully restore the original position, you have to repeat one move 24 times, that is, the corner has to be turned around 28 times.

A true lightweight.
Thank you for the images and the other answers.

Brilliant! Really like the concept of connection of the edges in mid-turn.

I'd like to ask two questions though: Does the "turning on opposite edges" work on the Gear Corner-Turning Octahedron too, as in your two tetrahedral gear puzzles? Also, any idea when we'll be seeing the Gear Corner-Turning Icosahedron?

Theoretically it should work, but I could not do it with only turning 2 edge elements - the friction is too high. To make such a move on GCTO, you have to spring between all edge pairs many times and turn each one a little bit - say, half a tooth.I'm not planning this, but even so you'll see Gear Compy Cube first, just because it's simpler

I made a very detailed review of this puzzle here. Enjoy!

-Doug

Nice review, thanks for sharing!

No problem! I noticed that besides your demo video, the designing process, and the TP topic, there was very little about this puzzle, so I thought I'd share a little.

-Doug

amazing!

gearamid?