Dan Shriver tabbydan at gmail.com
Wed Jan 3 16:39:51 EST 2018

```That's a decent representation.  But they simplified the "secular year"
(365 day part) to be one BIG ring/gear (to get around the problem of the
odd month at the end).

I'm wondering if there is some way to do it as four gears.

If it was just a 260 day cycle (20 months of 13 days each) and a 360 day
cycle (18 months of 20 days each) it would be relatively easy.

Something would simultaneously turn the 13 day ("sacred month") wheel 1/13
revolution and the 20 day ("secular month") wheel 1/20th revolution.  Each
month day wheel would have one tooth between the first and last days of the
month that tooth would cause the outer ring to rotate one spot (advancing
the "month").  The two outer rings would not need teeth between them (this
would reduce wear caused by things not being perfect in the real world and
thus having the months maybe not being perfectly in synch).

The big problem is that the "secular year" has 365 days and thus 19 months
with the last one being only 5 days.  If I call the last month Dec and the
first one Jan... I have an imperfect workaround.  The 20 day month ring has
2 teeth.  One between 1 & 20 (big tooth) and one between 5 & 6 (small
tooth).  The month name ring has a smaller inner radius for the last month
so it catches at 5... The problem is that instead of starting over on Jan
1, the first day of the new year will read Jan 6, not sure how to correct
that.

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On Wed, Jan 3, 2018 at 3:10 PM, Mark Peeters <peetersmarkg at gmail.com> wrote:

> I think this shows and describes the calendar cycles and how they go
> together.
> https://youtu.be/BeE-3BBqG58
>
> On Jan 3, 2018, at 12:25 PM, Dan Shriver <tabbydan at gmail.com> wrote:
>
> Looking at it again I guess it would be at least four gears because the
> "secular" 365 calendar is subdivided in an odd way.  18 months of 20 days
> each,  plus one special month at the end of just five days.
>
> The Aztec sun stone is odd because it mixes various info together.  It has
> calendric info but is not a calendar, it has some royal history, and in the
> center a prediction about how the 5th" sun/ world"  would end.  The Aztecs
> believed they were living in the 5th world or sun, of a sequence of such
> worlds/ suns.
>
> I am curious how that was generated since it could help me with the
> glyphs.
> On Jan 3, 2018 8:28 AM, "cbernhardt" <charlie at carols62.com> wrote:
>
>> I am not certain that this is the calendar you are referring to, but
>> attached
>> is a picture of an Aztec calendar produced in OpenSCAD from an AutoCAD DXF
>> file.  I can send you the DXF file if it would help.
>>
>>
>>
>> --
>>
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