Bookends With 200-Year Perpetual Calendar

This Instructable shows how to make a pair of bookends that has a 200-year perpetual calendar on one of them. This project is related to books and also inspired by a book. The inspiration is from my book “Practical Perpetual Calendars – Innovative, Convenient and Green” by James R. Saltvold, 2017. A pdf copy of it can be viewed at https://archive.org/details/9781532021367PdfOfBook . My book describes the unique concepts that I have developed for making standalone perpetual calendars, and suggests applications for these concepts. When I wrote my book, I did not think of a bookend as an application. However, a perpetual calendar on a bookend does not require any additional space in your office or on your desk, so is a good place for it if you have a conventional calendar elsewhere. A perpetual calendar that can display any month in a 200-year period by simply moving a slider is a very useful tool for any office. It can determine the day of the week for any date of interest. 

The basic concept of the bookend calendar is the same as the moving window pocket calendar described in my Instructable, https://www.instructables.com/Fifty-Year-Pocket-Perpetual-Calendar/ . The bookend calendar is larger and has a double-sided window with 100 years on each side. 

The bookends require little skill and simple tools to make. A table saw is handy for cutting out the material, but hand tools can be used. The calendar requires a computer and a printer. If you have bookends, the calendar can be modified to fit them. 

The basic concept of the bookend calendar is the same as the moving window pocket calendar described in my Instructable, https://www.instructables.com/Fifty-Year-Pocket-Perpetual-Calendar/ . The bookend calendar is larger and has a double-sided window with 100 years on each side. 

The bookends require little skill and simple tools to make. A table saw is handy for cutting out the material, but hand tools can be used. The calendar requires a computer and a printer. If you have bookends, the calendar can be modified to fit them.

The following supplies are needed for the calendar:

Quantity       Description

1                   8.5 x 11-inch sheet of 60 lb cardstock

1                   9 x 12-inch sheet of Avery 76293 or equivalent self-adhesive laminating sheet

1                   small container of Mod Podge or white glue

1                   empty cereal box or other source of thick cardstock

The following supplies are needed for the bookends:

Quantity       Description

1                   piece of material 5/8 or 3/4-inch thick by 6 inches by 12 inches

                     (plywood, particle board finished on two sides, medium-density fiberboard, or

                     MDF is suitable)

1                   piece of hardboard 1/8-inch thick by 4 inches by 10 inches

4                   #4 x 1-inch flat head wood screws*

1                   small container of Mod Podge or white glue

*A Robertson head is preferred for the wood screws as the screw driver will not slip as easily when the turning gets tough. If using Phillips head wood screws, you may have to drill a larger pilot hole and coat the screws with white glue to fill the extra space before driving them in.

There are the following pdf files:

1. Pattern for Bookend Calendar

2. Construction Details

3. Notes on Calendar Construction and Excel

4. Images of Finished Bookends

The first file has the pattern that is printed to make the calendar. The second file shows construction details. Use it along with the description below to build the bookends and the calendar. The third file shows how to reconstruct the Excel file that was used to create the pattern. It is only needed if you want to modify my pattern. The fourth file has two photos of the finished bookends and an image of the calendar when it is set to March 2024.

Skip this step if you have existing bookends that you want to add a calendar to. See the pdf file “Construction Details” for suggestions on how to do this. 

The first thing to do is to cut the 5/8 or 3/4-inch material to size. Two pieces, each 5 1/4 inches high by 4 3/4 inches wide are required. I made the height the same as commercial bookends that I have had for years. The width is what is needed for a calendar that is easy to read. My commercial bookends are 4 1/4 inches wide. I could have made the width this size, but I happened to have a piece of 5/8-inch thick particle board that was 4 3/4 inches wide and decided to use it without cutting it down. 

After the thick material is cut to size, prepare the two pieces for staining or painting. My particle board has a thin laminate with simulated wood grain on two sides and does not need further finishing on its sides. Ideally the two side and top edges that are seen should be covered with wood veneer that can be finished to look like the simulated wood grain. The edges can also be painted. To prepare for painting, sand the edges. If the edges have some pits after sanding, fill them with white glue or a mixture of white glue and sawdust and sand again. I was more interested in demonstrating how a perpetual calendar can be built into a bookend than making a good-looking project, so I left the edges unfinished. 

Next, cut the hardboard tongues that the books sit on to size. Two pieces 3 5/8 inches by 4 3/4 inches are required. On my commercial bookends, there is three inches of tongue under the books. My end pieces are 5/8 inch thick, so I made the tongues 3 5/8 inches long. The width of the tongues is the same as the end pieces, which is 4 3/4 inches. The ideal thickness for the tongues is 1/8-inch. However, 1/4-inch material can be used if a thinner material is not available. The tongues are not seen when there are books on them so there is no need to find a material that looks like the ends. 

If the ends are going to be finished differently than the tongues, I suggest finishing them separately before assembly. For good looking bookends, the ends could be stained plywood and the tongues painted hardboard. 

The first step in attaching a tongue to an end is to glue it. This is to hold the two pieces together before the screws are put in. After the glue is set, use two #4 by 1-inch screws on each tongue to make a strong joint. Locate each screw one inch from the end. Drill a 3/32-inch diameter by one-inch-deep pilot hole. Then remove material for countersinking so that the head of the screw is flush with the bottom surface of the tongue. This is a bit of a delicate operation. Enough material has to be removed so the head will be sunk far enough, but enough material has to be left so there is sufficient tongue material under the screw for a strong joint. I held a 1/4-inch bit in my hand and removed material with it.

The first step is to print the pattern on 60 lb cardstock. Then use a small flathead screwdriver to make a score mark on the dashed line between the two sides of the window. The extra material on the right side and below the two parts is used to make part of the track that the window slides in. Draw a line one inch to the right of the pattern and a line one inch below the pattern to mark out the strips that will be used for the track. 

After the fold line is scored and the lines are drawn, cover the sheet with a self-adhesive laminating sheet. This strengthens the 60 lb cardstock and makes the window easy to slide. The laminating sheet can be eliminated by using thicker cardstock that has a glossy finish. 

Use a utility knife and a straight edge to cut out the outlines of the two pieces and the two strips that will be part of the track. Do the cutting of the strips so that two strips one inch wide by 4 3/4 inches long can be made. A metal straight edge is preferred. Plastic will work, but it is more easily damaged if the utility knife slips. Put an old magazine under the cardstock before cutting. Self-healing cutting mats are available, but I have found that an old magazine works quite well. After the outline of the moving window is cut out, fold over the righthand side of the window and glue it to the back side of the lefthand side. Be sure to apply glue to the fold area, the outside edges and where the edges of the window will be after it is cut out. When the glue has set, cut out the window. 

The above procedure results in an open window, which I recommend. Alternatively, the window can be two thicknesses of laminate. This is achieved by applying laminate to each side after the window is cut out. The resulting window has many imperfections when held up to a light, but they do not show when it is in place. When the window is laminate instead of open, the moving window assembly is more rigid. However, the rigidity is adequate when the window is open.

The window slides in a bottom track and a top track. Each track has a spacer that is slightly thicker than three thicknesses of 60 lb cardstock plus three thicknesses of laminate. I found that two layers of a cereal box is thick enough for a spacer. To make the spacers, glue two strips together that are about 1 1/2 inches wide by 11 inches long. Make sure that the glue covers one surface well. After the glue has set, mark out a strip in the middle that is 3/4 inches wide by 11 inches long. This will leave about 3/8 inches of waste on each side. Cut out the 3/4-inch strip and then cut it into two pieces that are each the width of the bookends, which is 4 3/4 inches. To cut through two layers of cereal box, two or three passes may be required. Once the first pass is made, following the same line to cut deeper is not difficult. The spacers can be made by gluing single layer strips together after cutting to width, but making sure the edges line up to make a smooth track may be difficult. 

Glue one spacer to the bottom of the bookend covering up the end of the tongue, and glue the other strip to the top of the bookend. Put a mark in the centre of each spacer. Check if the stationary part of the calendar (which has the day-of-month and month tables) will fit between the two spacers. Trim the top edge if the stationary part is higher than the distance between the spacers. Line up the centre marks on the stationary part with the centre marks on the spacers, and mark out how much has to be cut off each end to make the stationary part the same width as the bookend. Cut the stationary part to width and glue it to the bookend. Three half-inch wide strips of glue are sufficient. Apply a strip of glue to the back of each side edge and a vertical strip in the middle. There is no need to apply any glue to the back of the top and bottom edges. The stationary part has to fit tightly against the bottom spacer for the calendar to display properly in the window. There can be a slight gap between it and the top spacer. 

The one-inch-wide strips mentioned above are guides that hold the window in place as it moves along the track. Glue one strip on top of the bottom spacer and one strip on top of the top spacer. Apply the glue to the spacer and take care that no glue gets on the edge where the window makes contact when it slides. 

The final step is to install the window. Trim the top edge of the window if it is higher that the distance between the spacers. For smooth movement of the window, there needs to be a 1/16-to-1/8-inch gap between it and the top spacer. Slide the window into the tracks with the century of interest showing.

The left-hand instructions on the calendar, which are always partially covered by the window, simply say: “Set year under month. Note that Jan. and Feb. are in different rows for leap and common years. Ignore 29, 30 and 31 when applicable.” 

The right-hand instructions, which are also always partially covered, say: “Window is two-sided to cover entire 20th and 21st centuries.” 

In the month table on the stationary part, the top row applies to January and February of a leap year, the middle two rows apply to March to December of all years, and the bottom row applies to January and February of a common year. To bring attention to leap years, JAN and FEB are in bold in the top row and leap years are also in bold in the year table. The calendar always displays 31 days for the month, with 29, 30 and 31 to be ignored when applicable. 

If you imagine that the columns in the year table are labeled Sunday to Saturday from left to right, common years are under the day of the week that January 1 falls on and leap years are under the day of the week after the day that January 1 falls on. In the month table, the months are in columns that the day of the week that the first of the month falls on relative to the day of the week that the first of January falls on. 

To minimize the height of the year table, there are no empty cells. Thus, the first four rows in the 21st century year table are: 

2000   2001   2002    2003   2009   2004    2005

2006   2007   2013    2008   2015   2010    2011

2017   2012   2019    2014   2020   2021    2016

2023   2018   2024    2025   2026   2027    2022

and 15 rows are required to cover the whole century. 

If it were preferable to have the years all consecutive, the table would be: 

2000   2001   2002    2003                 2004    2005

2006   2007                 2008   2009   2010    2011

            2012   2013    2014   2015                 2016

2017   2018   2019                 2020   2021    2022

and 18 rows would be required to cover the whole century. 

Finding a year in the compacted table is a little more difficult than in a table that is consecutive with blanks, but reducing the table’s height is an advantage.

In addition to displaying the current month, your bookend calendar can be used to solve date problems. One is to find which day of the week your birthday is on for any year. Suppose your birthday is May 17, and you want to know the day of the week in 2030. Set the year column that contains 2030 under May, and note that it will be on a Friday. You can also find the years that your birthday will be on a particular day of the week, say Sunday. Set Sunday over 17, and under May note the years 2026, 2037, etc. 

Sometimes you can use the calendar to guess a date. Your birthday is May 17 as above. You remember celebrating it on a Saturday in Banff National Park a few years ago, but you cannot remember the year. Set Saturday over 17. The years under May are 2003, 2008 and 2014. This is the year 2024, and you thought that the occasion was only five or six years ago, but it must have been 10 years ago in 2014.