Hey everyone-

NOTE, text and videos are interspersed with the images below.

I was thinking recently about ways in which a Big Chop might be able to be made using 60 identical copies of 2 parts. Thinking about the cheats we sometimes use to estimate tough integrals in computer science, I thought of an idea. Each part would have one shell or rail at the same level. When two parts near each other, they collide and one randomly goes up while the other randomly goes down.

The parts are designed so that no matter which wins, the rails interlock.

I have designed 6 versions of the Big Chop puzzle using variations on this theme. I'm not at a stopping point, but I wanted to share my progress with everyone here that's interested in mechanisms.

Here are a few images of a variation with wider rails, and holes cut in the rail arms to make them springlike.





You can see that they hold together, randomly fitting whichever way I happen to push them together like velcro.


Here's a demo video demonstrating the velcro like quality.



I have tried multiple rail sizes and widths. Strangely thinner rails seem more successful. These images show the thinner rails:




I have also tried stochastic combs, which are collections of shells that randomly go one way or the other like "bristle blocks". These seem to collide much more making the puzzle useless. But I think I'll try again sometime anyway.



Here's an assembled example using the most successful design to date.


Turning is just painful.
The stochastic moments all seem to want resolution by hand-jostling, even though small collections of parts work well.

Since turning is so tough I sped up the video 8x. Yeah, I was resolved to get one turn.

Big Chop using Stochastic Rails

So you made the first Big Chop mechanism that doesn't use magnets. Let me be the first to say, Awesome! Although I still think this is just a silly puzzle.

I call that a brave attempt.
I have to edit the entry in the museum ...

Seems like this could be a promising idea, well done.

This is really incredible. As you can see, I an especially excited about this. I have wanted this to happen for months!
Amazing.

-Doug

Nice ! I experimented on this mechanism a few times but didn't end up printing it

Still I view this as a very significant step on the way to a well turning Big Chop. I can remember the very first Pentultimates and their turning has improved drastically since the first attempts. Its just this kind of experimentation that is necessary to get us there.

Now a quick question. In this pics and video you only show non-jumbling moves/positions. Does this mechanism also support jumbling? I suspect that is does but its hard to tell from what's been presented.

Great work... thanks for sharing,
Carl

Thanks a lot you guys!
As you can tell, I've been printing quite a few failures based on this idea, so it's great to hear positive comments about the progress.

Carl, yes this mechanism does support jumbling. If I'm brave enough tonight maybe I'll give that a try on video.

There are some variations on this idea that wouldn't support jumbling. I don't like to jumble puzzles when I solve them, but to me the "true" version of this puzzle should jumble. What do you guys think?

Also, I should say that TomZ told me yesterday that Bob Hearn was considering big chop mechanisms using identical pieces as well. We must be on the same brain wavelengths.

Thanks. I'd like to see that.Interesting... it would seem harder to dis-allow jumbling then it would be to allow it. Could you show such a variation?Oh my ideal Big Chop would certainly allow jumbling. Of course you could always scramble and solve it without using jumbling moves. While we are on that topic, does anyone know if its possible to scramble a Big Chop using jumbling and then to restore it to the dodecahedron shape and end up in a state that one can't solve unless they resort to rumbling moves? I know the Helicopter Cube has this property, well except we are talking about a cube in that case, and to me that adds alot to my interest in the Helicopter Cube. I would hope this is also true of the Big Chop but I honestly don't know if it is.Well they can't all be identical, I would think at best you have two piece types which are mirror images of each other.

Carl

One possibility I've been considering is letting the stochastic part of the mechanism happen inside the core, with each part reaching into the core and presenting a small sheet inside. In this case, the core would have the smallest cuts possible to allow all turns. But it wouldn't allow jumbling.

One other interesting thing-- I've considered my Pentv2.5 mechanism for the big chop, and it has the same problem due to the core. It might allow one or two jumbling moves, but after that it could get blocked badly when it shouldn't because the internal mechanism assumes the non-jumbled geometry. If you think back to the mech for the pent v2.5 you saw, that might make sense.

Oh, and you're absolutely right, when I said identical pieces I meant 60 copies each of 2 mirror images of the same piece.

Carl, Here's a demonstration of a jumbling turn.

Again, turning is so awful I sped it up 8x during turns.

Video Of Jumbling Big Chop

So how does it work for a little chop then?

Yes, that makes perfect sense. For the sake of the pent v2.5 mech we are very lucky the pentultimate doesn't jumble.NICE!!! I believe this is the first Big Chop which has ever been shown in the jumbled state. I'm not sure if the ones with magnets would allow this or not. You should post a couple high res pics of the puzzle as seen in the last state of that video. Its very cool just to see what a jumbled state looks like.

Carl

I have three questions for IO. Will this puzzle ever be flat that your working on? What does Oskar think of this? Since you are working on the Big Chop that he made with magnets. I just wanted to know your thoughts on a question that I saw a while ago. Can a Big Chop be made from a Master Pentultimate?

I want to know if these pieces are truly random, or if the up and down movement is controlled by something. Can anyone answer this?

He appeared quite fascinated when we talked about this last night. I think he would be quite happy for anyone to make a functional big chop. I think he would like to see a move video at normal speed and I agree. From the current video it's impossible to see what it's like.


No, I can not think of any sensible way to do that. They're very different in geometry.

I'm using random loosely. It's pseudo-random based on small variations on how you hold the puzzle.


1. will it be flat? -- I won't be happy until I or someone makes a nice version with flat faces, yes.
2. I've spoken about the Big Chop with Oskar a bit in the past, but didn't think to ask his permission. The tone of the conversation definitely implied permission and a hope that someone will get one working.
3. Master pentultimate? No-- I don't think so. But a MP can be used to make a pentultimate.


I'll be happy to post a realtime video if you're interested, and I'll be able to say "you asked for it." when you see how painful it is to behold. I may even have it here at work. I'll check.
Again, it's pretty awful to turn, and even the sound of the rails deciding which way to pass each other sounds like someone snapping celery.
This is an experimental build, and certainly doesn't count as a usable version of this puzzle.

Very clever mech. It's exciting to see new ideas after previous attempt painted a bleak outlook for a big chop ever existing.


I'm not a puzzle designer so feel free to take my thoughts to improve it with a grain of salt.

Does the leading edge of the rail have a tapered end so they're easier to deflect?

Would it be worth testing this mech on a simpler puzzles like a 2x2, skewb, or little chop? Though I'm thinking about the 2x2 and having the entire rail deflect one way or another may be an issue because it's rail is so curved.

In the Over the Top 17x17x17, Oskar used what he called floating anchors to help pieces stay aligned. They seemed to work really well there. Though they may not be that effective if your main issue is in/out displacement instead of lateral alignment.

It seems to me that a piece riding high will favor a high connection on it's next rail alignment too so the high stay high and the low stay low.

Combs work worse because it's likely that the different levels might try to split in different directions.

Have you considered giving this thing a proper central ball connected to one of the outer pieces, then putting bumps in the ball the force pieces up before they meet, breaking the ties?

Sorry about the bump, but has there been any progress on this? I'm really looking forward to it.
Have you tried applying the same mech to little chop as well?