cacb wrote

I re-installed the 64 bit version of OpenSCAD 2015.03-2 and it seems to be
working fine.

OS Win 7 64
OpenSCAD version 2015.03-2
Intel Core i7-6700
3.40GHz
16GB RAM

with linear_extrude
render F5 4 seconds
render F6 4 seconds

linear_extrude removed:
render F5 4 seconds
render F6 4 seconds

Thanks for all the help,
Charles

--
Sent from: http://forum.openscad.org/

So I'm not trying to beat a dead horse here.... but I'm trying to figure
out how to make the "solar" 365 day calendar more like the "ceremonial" 260
day one.

The 260 day calendar has months (20) with exactly the same number of days
(13) so it is easy to implement as two gears.  One has 13 spots and one
tooth.  The other has 20 notches (one for each month)

The 365 day calendar has 18 months of 20 days and one month of 5 days.

I have a simplified drawing for how I'd like to tackle this.  For
simplification I've only put notches in the outer months ring in four spots.
The ceremonial calendar is on the left and the solar one on the right.
For the solar one it would have 18 notches between the months (that the
tall tooth between 20 and 1 would catch), and a small tooth on the month
ring between the first and last months of the year (calling them "Dec" and
"Jan" here since that is easier to write than a glyph) that would catch on
a small tooth on the month ring between 5 & 6.
The result would "sort of work" except the first day of the new solar year
would be Jan 6.

Are there any clever tricks I could use to reset the day of the month wheel
after "Dec 5" so it reads "Jan 1" the next day?

[image: Inline image 1]

On Sat, Jan 6, 2018 at 10:33 AM, cbernhardt charlie@carols62.com wrote:

A Geneva drive with irregular 19 pin arrangement?

2018-01-11 20:57 GMT-02:00 Dan Shriver tabbydan@gmail.com:

I looked up the Geneva drive and see that it would solve an unstated
problem of mine.  If I used a Geneva drive with one pin and the cross on
the underside of the "day of the month" wheel, it would change a
continuously turning motion into discrete movement of the day wheel.

I believe you have an idea for how to reset the day but I do not understand
it.  Can you provide a diagram of how it works?

Maybe if I have a second cross at the top of the solar month day and there
is pin (not sure if it would need to be on a spring or not) on the "month
of the year" wheel that causes the "day of the month" wheel to spin back
from 5 to 1.  The only problem with that is I would have to somehow
disengage the Geneva drive on the bottom...  I'm sure that's not what you
are suggesting (since you mentioned "19 pin irregular").  I'm just having
trouble imaging what you are saying.

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On Thu, Jan 11, 2018 at 6:38 PM, Ronaldo Persiano rcmpersiano@gmail.com
wrote:

My knowledge of mechanisms is very basic. But, yes, the purpose of Geneva
drive is to produce an intermittent motion from a continuous rotating
motion drive. It is an indexing system that may have its place in your
project.

I tried to design my idea but failed: I don't think Geneva drive would do
the trick. In fact, I think now a better solution for your quest would be
to consider a variable sectional gear mechanism like the one is found
in Gearwheels
from Hell http://www.douglas-self.com/MUSEUM/POWER/gear/gear.htm. Those
mechanisms allow to have two or more gear transmission ratio during the
rotation. But don't ask how, at least not now. :)

However, I guess the best solution to assign month names to the 365 day
Mayan calendar is found in the Youtube video Mark Peeters referenced here
days ago. In the video, there are three geared wheels: one with 13 numbers,
one with 20 day glyph names and, the year wheel, with 365 days. The year
wheel have 365 combinations of a month day number and a month glyph. There
are 19 month glyphs, one of them appearing just 5 times on the wheel and
the others appearing 20 times. So the months are not in a separate wheel
but in the 365 day year wheel. If you stop the video at 1:38 you will see
the 5 day month in detail.

Each specific combination of one number (first weel), a day glyph (second
weel) and a pair [day number, month glyph] are aligned just once in 18980
days. This is the Calendar Round of 52 years.

2018-01-12 16:23 GMT-02:00 Dan Shriver tabbydan@gmail.com:

Hi, Dan.

I have worked a bit on the idea of using sectional gears to solve your
quest about the month wheel in the Mayan Calendar Round. I designed two
sectional gears: one for the month wheel and one for the year wheel. The
first one has 76 teeth (one for each 5 days) with 7 missing teeth. The year
wheel has 73 teeth (one for each 5 days as well) with no missing teeth. The
missing teeth of the month gear allow that the wheel rotates 4 times faster
them usually during the short month transition. The included animated gif
shows the transition of 5 "unlucky days". Another pair of sectional gears
would be responsible for this transition (I haven't designed them). The
design of the two shown gears is not correct yet because of a small tooth
crash at the beginning and ending of the transition but some "light
filling" of two teeth of the month gear would solve that.

Animation: MonthTransition.gif
Animation code: mayanSGears.scad
Month gear: monthGear76_7.svg
Year gear: yearGear73.svg

In this design, the two wheels have approximately the same big diameter. I
don't see any way to avoid that.

2018-01-12 20:12 GMT-02:00 Ronaldo Persiano rcmpersiano@gmail.com:

it might be worth your while to research the antikythera mechanism
especially the fractional gears

I never knew you could half a gear tooth... with different ratios with
fractions you should be able to reduce the need to have long sectional
gears (hopefully)

On 14/01/18 22:11, Ronaldo Persiano wrote:

Thanks Chris and especially Ronaldo.

I'm still digesting Ronaldo's solution (I confess to being a bit slow about
it).

I was wondering about the Antikythera mechanism too (forgot its name, which
I should commit to memory as it is the first computer).  Also wondering
about old clock that would mechanically put the day of the month.

I'm trying to make the mechanism with as few parts / gears as I can, but
also I want to separate the different cycles (day of month, vs month of
year)

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On Mon, Jan 15, 2018 at 7:17 AM, Chris Camacho chris@bedroomcoders.co.uk
wrote: