Icosacalendar

Introduction

The Bahá’í calendar, also called the Badi’ calendar, is a solar calendar introduced by the Báb and refined by Bahá’u’lláh. It consists of 19 months, each of which is named after an attribute of God. Each month lasts 19 days, and there is an epagomenal period of four days (with a fifth intercalary day on leap years) called Ayyám-i-Há placed between the penultimate and ultimate months. Like the Jewish, Christian, and Muslim calendars, the Bahá’í calendar uses a 7-day week. The year starts around the spring equinox, with the month of Bahá, or Splendour.

This project lays the 19 months plus Ayyám-i-Há over the surfaces of a 20-sided regular polyhedron called an icosahedron. This document contains instructions for printing and constructing the 3D calendars. The code I wrote to generate the pattern and calendar images can be downloaded at the bottom of the page.

All media files included or linked to in the ensuing sections were made by me, and are licensed under the Creative Commons Attribution-Non-Commercial 2.5 Canada Licence.  This means you can use them freely so long as you attribute them properly, and don’t sell them without permission.

Creative Commons License

Materials

  • A computer and printer
  • Printer paper
  • Construction paper (or some other suitable heavy-weight paper)
  • Ruler
  • Sharp scissors
  • Pen and pencil
  • Glue stick
  • White glue
  • Scotch tape
  • Small glue spreader (e.g. toothpick, staple, etc.)
  • About 2 square feet of table space

Printing

First you need to print the pattern image and the calendar image. I have prepared PDF files for easy printing of large calendars (about 7 cm face-to-face, one calendar per page) and small calendars (about 5 cm face-to-face, two calendars per page):

Large Icosacalendar, separate pattern and text.
Large Icosacalendar, combined pattern and text.
Small Icosacalendar, separate pattern and text.
Small Icosacalendar, combined pattern and text.

With the separate pattern and text, those two components are printed separately and the pattern is traced over the text printout, leaving the pattern invisible after the calendar is folded.  The combined pattern and text is less fiddly (perhaps more suitable for younger cohorts), but it will leave the pattern’s black lines along the edges of the calendar.  The instructions below assume that you are making the large icosacalendar using separate pattern and text.  Users of the combined version can print the corresponding image to construction paper and skip to the section “Cutting and Folding the Calendar” below.

You can download the raw 8 megapixel images for the pattern and text here:

Pattern Image
Text Image

These can be used to make differently-sized calendars.  Just copy and paste them into a word processor document and resize them.  Make sure that both images are scaled by the same amount, so that they wind up being the same size on paper.

Print the pattern page onto regular printer paper using normal settings.  If the printer resolution is not high enough then some lines might not appear, in which case you can draw the lines in with pencil.

Print the text page onto construction paper using the printer’s high-resolution settings.  You might need to trim the construction paper if it’s too big for the printer.

Cutting and Tracing the Pattern

Now you have something like the following pieces of paper:

The pattern printout.The large pattern image printed out onto a piece of printer paper.

The calendar printout.

The large text image printed out onto a neat-o piece of yellow construction paper.

Cut out and fold the pattern.

Cutting out the pattern.

Cutting around the outside of the pattern. Be sure to cut between the outer arcs all the way down to the bottom of the corner, or you won’t be able to fold it properly.

Folding the pattern.

Folding strategic parts of the pattern.

Folding the pattern.

Making a sharp crease with a ruler.

I fold the pattern by placing a ruler on the line I want to fold, pulling the paper up against the ruler and then flattening the crease with the ruler. You don’t have to fold all the lines on the pattern, just the ones needed for the positioning steps that follow.

Position the pattern over the calendar

Positioning the pattern.

Positioning the pattern over the calendar vertically.

Get a couple small pieces of tape ready before doing the positioning. Carefully position the pattern over the calendar by lining up the creased folds on the pattern with the calendar text.

Positioning the pattern.

Positioning the pattern over the calendar horizontally.

This is a pretty tedious procedure. You’ll probably have to make minute adjustments to the pattern’s position, making sure the creases line up with the month names equally above and below, and with the 8’s and 14’s equally on both sides of the calendar. This is important because if the pattern isn’t lined up precisely on all sides then the text will be off-centre somewhere. Of course, this is way less hassle if you aren’t as obsessive as I am, but I think it’s worth the extra couple minutes to produce a nicer result.

Once the pattern is positioned, secure it to the calendar by taping it at either end. Place the tape over the tabs at the ends of the pattern, so that it won’t tear off part of the calendar when it comes off.

Trace over the pattern

First, trace around the pattern outline in pencil.

Penciling in the pattern outline.

Penciling in the pattern outline. I use the ruler to keep the pattern flat and straight.

Next, use a ruler and a pen to trace the pattern lines onto the construction paper. You have to apply enough pressure with the pen to leave an indent on the construction paper.

Tracing over the edge lines.

Tracing over the edge lines.

If you’re making a lot of calendars, then you can re-use an already-cut pattern to save time and paper, but beware: tracing the lines over and over again wears through the paper.

Finally, lift the pattern, make sure that all the marks are where they should be, and detach the pattern from the calendar.

Verifying the lines.

Verifying the indents and outlines.

Finished!

The tracing is completed. Hooray!

Cutting and Folding the Calendar

Next, cut out and fold the calendar. This is the same as cutting out and folding the pattern, except this time you fold all of the edges backward instead of a few of the edges forward. Between cutting and folding, erase any pencil marks around the calendar cut-out’s tips and corners (you don’t need to erase the marks on the tabs, since those will be glued inside the calendar).

Erasing extra pencil.

Erasing the pencil from the corners and tips of the calendar leafs.

Using the indents as a guide, fold all of the edges up, then back, so that the calendar becomes a concave surface with the writing on the outside.

Folding the calendar.

What the calendar looks like after folding everything back.

Gluing the Calendar Together

Starting at one end, glue together the tabs using a glue stick.  When you glue two tabs together, squeeze them up against the wall of the calendar to make sure the bond is strong. Squeeze them back and forth until, when you straighten them out, the seam on the outside of the calendar is even.

Gluing tabs together.

Squeezing two tabs together against the calendar wall.

Bad seam!

This seam is not straight and needs some more work.

It can be helpful sometimes to give the glue time to dry before gluing the next sets of tabs together.

Continuing to glue...

Squishing the calendar like this makes it a little easier to manoeuvre inside the cavity.

You should end up with four tabs left unglued, so that the calendar looks kinda like a squid’s beak. Avoid leaving two sides of the same triangle unglued, because that makes the final glue job very difficult. For the last gluing, switch to white glue so that the opposing tabs will adhere without having to be pressed together hard from the inside.

At this point you may also choose to put something in the calendar to weigh it down, e.g. a clean stone or some rice, thereby making a handy paperweight or percussion instrument!

Aaaaargh, colossal squid!!!

This is what I mean by a squid beak. You don’t need very much white glue here, just enough so that the tabs stick together without much pressure being applied.

Spread the glue around so that it covers all of the tabs. I use a staple for this because that’s what I have, but a toothpick or something would work too.

Spreading the glue.

Spreading the glue around the tabs.

Finally, gently squeeze the squid’s beak closed, align the seams, and hold it for a couple dozen seconds. If you applied too much white glue then it will squish out of the seams and you can just scoop it up with the corner of some scrap paper.

Holding together the final seam.

Holding the final seam together while the white glue becomes tacky enough to stick.

Leave it to dry for a while, and ta-da, you have a totally sweet 3D Baha’i Calendar.

Finis.

The final product.

Code

The code I used to generate the pattern and calendar images can be downloaded here:

Icosacalendar.zip

It was written in C# using Visual Studio 2008.

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