aeh5040

These wheels look interesting

Long ago I bought a used 8480 and found that someone had added tiny ball bearings inside the turntable. It was quite effective at making it turn better.

Leap year - yes, exactly that! I did try this, but it ends up pretty bulky and heavy. The cylinder is lighter weight. Thank you for the encouragement! We'll see whether it actually works...

Some progress on the leap year selector mechanism: Seems a bit of a shame to put stickers on this drum, but trans blue was the most affordable colour!

The geometry is proving quite tricky!

Not more complicated. All this is accounted for, except that I will stick to the Gregorian calendar 1600-2400.

Wow, impressive analysis and results! Curious how the total error graph kind of looks like two line segments rather than, say, a parabola. Could be just my mental over-fitting though!

In case anyone is interested, I experimented with custom diffs like this to reduce the gear lash, but there was way too much friction, not to mention the bulkiness. The current approach seems the most promising.

I think most of those listed are really variations on the same one. Thanks for your interest!

The yellow one is bizarre! But potentially a useful tool for half spacing.

Thanks! Not exactly - the plan is for it to work similarly to the methods described at https://en.m.wikipedia.org/wiki/Determination_of_the_day_of_the_week. So there will be a month dial with 7 (or more likely 14) positions geared to the month knob, with the months suitably arranged (not in order) around it. Some of the slots will have more than one possible month in them. The dial for the last two digits of the year will have 14 positions, with leap and non leap years alternating, and again many different years in each position. In my head I have a fully functional design, although the practicalities won't be easy. Not sure whether I'll actually get it done by the deadline, but in any case it will provide good motivation! Handling the year 2000 (and 1600 and 2400) presents an extra challenge, since they are leap years, but other years ending in 00 are not. I think I have a solution to this that is actually a bit nicer than the calculating methods listed on Wikipedia. More to come...

Not quite sure what to call this thing... A machine to instantly calculate the day of the week for any calendar day of any year (e.g. birthdays, etc.) There will be four hand turned knobs to select the century, year, month and date, and the day of the week will then be displayed. The idea is to do it with differentials, and lots of 1:7 gear ratios. Leap years will be accounted for automatically by an extra lever that adjusts the selection for Jan and Feb (hopefully!) The biggest enemy is gear lash. However, I believe my current prototype shows that it can be done (just). I use a very precise detent mechanism for the knobs, and then gear up before the differentials and down at the end... Hopefully custom stickers for the dials are allowed... A long way to go!

Animals (real or imaginary) would be great!

Yes it does, although I don't immediately see as many applications...

Following on from the discussion of gear clearance above, I recently discovered that this works (perhaps it is already known to others?):

It's very hard for anyone to help with so little information to go on. I suggest you at least post some pictures or video.

This looks really useful! It would be nice to have a version that works with the in-grid train wheel bearing (if that's even doable with the small bananas).

That's very nice! There are several good ways to make a working Geneva drive out of pure Lego, but of course they are nowhere near as compact as this.

For me even the excitement of owning *four* 40t gears was almost too much at the time!

I don't have specific data, but in my experience knob gears perform very poorly under load especially when run for an extended period. The surfaces degrade quickly, increasing the friction, and after a while pieces start chipping off the teeth.

8480!

Oops Many thanks for the render! I find it interesting that this is enough to hold it together...

Yes, it's fully mechanical. There is just one motor, running continuously. It would not work from an arbitrary arrangement of discs - only one on the shortest route between start and finish. However, it's not a predetermined sequence - it does "work it out" as it goes along. In principle it would work with 10 or any number of discs (although not practical with LEGO). The three pegs have different colours. After it transfers all the discs to one, it moves on to the next, and so on forever. There are quite a few more details in thread about v1. This was partly pneumatic, but used otherwise the same method. https://www.eurobricks.com/forum/index.php?/forums/topic/168443-moc-mechanical-tower-of-hanoi-solver/

This is brilliant! Elephant simplicity, and at the same time it's clear how much thought has gone in to it. Do you happen to have some static pictures of the wheels? The internal structure is not obvious to me.

Probably the Tower of Hanoi solver. Still not completely happy with it, as it's not really reliable enough to run at a show: https://youtu.be/MHBsQS34Tu8