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THIS IS THE TEST SITE OF EUROBRICKS! ×
THIS IS THE TEST SITE OF EUROBRICKS!

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Posted (edited)

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!

IMG_20250112_120857991.jpg

IMG_20250112_120839946.jpg

Edited by aeh5040
Posted

Wow, that's a very interesting and ambitious project. I believe You would need some way to encode the length of individual months to make this work?

Posted (edited)
13 minutes ago, Davidz90 said:

Wow, that's a very interesting and ambitious project. I believe You would need some way to encode the length of individual months to make this work?

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...

Edited by aeh5040
Posted
1 minute ago, Davidz90 said:

Really interesting, this topic seems to be a real rabbit hole! I wasn't aware that there are so many different algorithms!

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

Posted (edited)

Very interesting. Maybe you can also add the 12 Chinese animal zodiacs and/or the 7 Buddha postures of the determined week day :classic:
The latter is easier. I'm a Horse and have the reclining Buddha.

The Bilion year clock of Brick Technology has year subtractors, maybe it helps. It also has one 3D printed gear to enable the clock, I hope you don't need one.

Good luck and fun with the build.

Edited by Berthil
links added
Posted (edited)

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.

IMG_20250112_153544171.jpg

Edited by aeh5040
Posted

To make you more complicated; leap years have three criteria:

- year must be bigger or equal 1584

-  year must be divisable by 100 and 400 at the same time and

- year must be divisable by 4

Posted
4 hours ago, 1gor said:

To make you more complicated; leap years have three criteria:

- year must be bigger or equal 1584

-  year must be divisable by 100 and 400 at the same time and

- year must be divisable by 4

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

Posted (edited)
5 hours ago, aeh5040 said:

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

That is exactly what I meant; on February 24th 1582 Pope Gregory III introduced this civil calendar after Papal bull Inter gravissimas and after 4th october next day was 15th to make necessary corrections based on study taken by physician and  astrologist Aloysius Lilius...

Edited by 1gor
Posted (edited)

Some progress on the leap year selector mechanism:

IMG_20250115_215919884.jpg

Seems a bit of a shame to put stickers on this drum, but trans blue was the most affordable colour!

Edited by aeh5040
Posted
51 minutes ago, aeh5040 said:

Seems a bit of a shame to put stickers on this drum, but trans blue was the most affordable colour! 

You can always take them off and clean it :)

This looks like a huge project, I wont pretend I understand how you're doing it. Good luck and great work so far.

Posted

The year is selected first then the red carriage will move to one of two positions depending if it's a leap year or not, if I understand correctly?

1 hour ago, aeh5040 said:

Seems a bit of a shame to put stickers on this drum, but trans blue was the most affordable colour!

Maybe you could use the 14-tooth sprocket with treads with tiles attached:

42529.png

Posted
34 minutes ago, ord said:

The year is selected first then the red carriage will move to one of two positions depending if it's a leap year or not, if I understand correctly?

Maybe you could use the 14-tooth sprocket with treads with tiles attached:

Leap year - yes, exactly that!

I did try this, but it ends up pretty bulky and heavy. The cylinder is lighter weight.

1 hour ago, Aurorasaurus said:

You can always take them off and clean it :)

This looks like a huge project, I wont pretend I understand how you're doing it. Good luck and great work so far.

Thank you for the encouragement! We'll see whether it actually works...

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