Making a Stainless Steel Rubik's Cube
lulabs.net
lulabs.net
> The face centers each receive a hollow stem that screws into the 5/16-24 thread. This assembly holds a captive spring-loaded screw, which screws into the core. The spring provides some give to the entire unit and allows the cube to be assembled and disassembled easily by snapping pieces in.
Brilliant!
Long story short, a random chinese Rubiks cube knockoff is quite likely to be higher quality than an actual Rubiks brand cube these days.
The ingenuity required to get things like this one on manual tools (especially pre-DRO, but even now) is amazing. Starting out machining, I expected the machining to be the hard part, but often a lot more time is spent on planning, fixturing, set-up, and so on. For example, the idea of making custom vise jaws to hold odd-shaped parts seemed crazy to me the first time I heard it, and now its just a completely normal way to behave. CNC makes things a whole lot easier, from being able to do complex shapes with CAD/CAM, to simple things like interpolated circles (when the mill cuts a circular shape by moving X and Y simultaneously, a seemingly trivial thing that's nearly impossible on a manual*). Having a 4th or 5th axis makes complex stuff even easier, and often completely avoids the need for wacky fixturing.
The lathe fixturing here is especially fun. A lot of old hobby books are written assuming you have only a lathe and no mill. Fun, often scary, fixturing was the order of the day.
* Ok, you can do crazy things with boring heads, but getting it right is really hard.
Does anyone know of a good route for learning the software stack associated with this stuff? I keep up with some maker YT channels like Stuff Made Here and they usually do an okay job of showing which machines were used and how each piece was made. But what they usually never show is which programs they used to model and mock up their creations before they started machining.
I'd really love to learn more about CAD modeling and designing these kinds of projects but I don't know how to get started.
In general, the aspect you're asking about is called an "assembly" - where you can bring in multiple parts that you have designed (and even design new parts "in place") to see how they go together and, to a minor extend, interact. I say "minor extent" there because most assembly systems aren't running full physics simulations or collision detection, at least most of the time - SolidWorks will happily let you design and assemble a model that is physically impossible to put together, while letting you rotate bodies through each other.
So yeah, I'd recommend starting with Fusion360. There are plenty of resources out there for learning it, but I do know that Grimsmo Knives and NYC CNC have videos showing how they specifically use it.
Here's what seems like a very in-depth video from Grimsmo on 5-axis machining (so definitely not applicable to just starting to learn, but this is the first I found - I know plenty of their other videos have details about fixturing and setup): https://www.youtube.com/watch?v=XqhctiVZtRU
NYC CNC has an entire playlist called "Fusion 360 for Beginners": https://www.youtube.com/nyccnc/playlists ; I haven't watched any of that, but I've watched plenty of their videos and enjoyed them, so think that playlist should be at least a bit helpful.
There's plenty more detail here, but I don't have the time at the moment to dig deeper - if you have any questions, feel free to leave them here and I'll see what I can dig up.
FWIW, SolidWorks does have a low cost option ($99 a year):
https://discover.solidworks.com/makers
And arguably there also features included in the above that are not available in the free version of Fusion 360 (available in the paid version, which has similar licensing costs to full blown SolidWorks).
I'll absolutely dig into this stuff more. Even just knowing about the assembly thing is very helpful.
Also, face the reality you won't be doing work like this on day one. But you will make something fun.
On a side note, my mechanical engineer acquaintance complains that he should have followed the CS route because programmers earn substantially more here. The grass is greener.
But these days, I do highly recommend Onshape -- it breaks down a lot of the 'rules' that I thought I knew about CAD software. I started using it about two months ago; one of my clients uses it for real industrial design of some IoT hardware, so it is powerful enough to do real things. Before I started using Onshape, I thought that 1) all CAD software was a million billion gigabytes, and required stupidly powerful hardware for no readily apparent reason, and 2) had an annoying licensing model that requires you to jump through hoops to get access to the free tier. Well, neither of these are true with Onshape: I went from 'hmm, maybe I should try this for my personal projects' to 'constraining a sketch' in about 90 seconds ... on Linux ... in Firefox ... on my Shenzhen ThinkPad ... with an Intel GPU. I was blown away at how much it failed to suck.
Anyway, my suggestion on choosing software is: it probably doesn't all that much matter. What you want to learn is the CAD mindset, not the software. An experienced MechE once told me that if you are not careful, you can end up writing 'spaghetti CAD'. These tools these days give you a lot of features that are, in theory, more expressive, but in practice, can result in unmanufacturable parts or unmaintainable designs: be careful!
So I take it you have never seen OKAD? ;) http://www.ultratechnology.com/okad.htm
Then you could probably test using a desktop CNC machine at some kind of maker space (or even some libraries now have them!)
Follow up idea, which I'm sure adds tons more complexity: have each face be a different material or finish. E.g. one face is stainless, another anodized aluminum, zinc plated for a third, brass on another. Each of the edge pieces would have to be a two-part assembly, and the corners composed of the three materials joined together (joinery, screws, brazing).
That surely would feel strange with the varying densities and thermal masses while solving, but would look very cool. To be fair, it appears from the pictures that each center piece's pattern is symmetric, which avoids the difficult part of aligning those when solving (center often doesn't line up when solving a cube with pictures on the faces in place of a solid color).
Probably far too niche for selling these to be profitable, but I'd love to have one.
I don't understand this. If you have a corner piece in the wrong corner then won't the colours on the adjacent faces be wrong?
Here's a video explaining special algorithms to rotate only the center piece: https://www.youtube.com/watch?v=fk1eCZNCTB4
https://en.wikipedia.org/wiki/Mirror_blocks
(The mirror cube is my favourite shape mod!)
Regarding the Stainless Steel Rubik's Cube. What a work of art!
This was the punchline I was looking for. The aluminum version seem like a more desirable version at 500g.
Tungsten is famously hard to machine, but ultra-pure tungsten is supposed to be OK.
Strangely, osmium oxide is a gas.
Iridium might be the better choice.
I am not sure what steel you would need. Something dimensionally stable, to be sure.
Seriously, I want to buy this, like right now...
I wonder if the relative similarity of the designs on the faces makes it particularly difficult to tell them apart, although if it's mostly for display that shouldn't matter much.
> The flat bottoms of the face centers do not allow the cube to turn as smoothly as it should; a problem that was rectified with a different design in the new cube.