Wall Clock With Built-In 100-Year Perpetual Calendar

The purpose of this Instructable is to show how to make a wall clock that has a built-in 100-year standalone perpetual calendar. A clock with a built-in calendar is both a novelty and a useful device. The emphasis of this Instructable is to show concepts rather than to show how to make a fine finished product.

The standalone perpetual calendar uses the same concepts as the tent desk calendar described in my Instructable “Perpetual Calendar Breakthrough”. (See https://www.instructables.com/Perpetual-Calendar-Breakthrough/ .) These unique concepts are described in detail in my book “Practical Perpetual Calendars – Innovative, Convenient and Green” by James R. Saltvold. (A pdf copy of my book can be viewed on https://archive.org/details/9781532021367PdfOfBook/mode/2up .)

Materials

Three sheets of 8.5 x 11-inch 65-lb. cardstock

Two sheets of Avery 76293 or equivalent self-adhesive laminating sheet

One 6 x 9-inch piece of 0.125-inch-thick hardboard

One 36-inch-long piece of spruce or pine that is 0.75 x 1.0-inch cross-section

One 8.5-inch-long piece of 16-gauge iron wire (see Step 9 for alternatives)

One 3.5 x 9.5-inch piece of thin corrugated cardboard that is less than 0.125-inch thick

Two brass-plated traditional picture hangers, 20 lb. rating

One quartz clock movement mechanism

Mod Podge or white glue

A small quantity of bathtub caulking material or other caulking material

Tools

Table saw

Utility knife

Metal straight edge

Small paint brush approximately 0.5 inches wide

Pliers

Miscellaneous small tools

Parts

The above photos show the main parts which can be thought of as layers. From back to front the layers are:

1. The frame which is an 8.5-inch square made from four pieces of spruce or pine that has a 0.75 x 1.0-inch cross-section.
2. An 8.5-inch square sheet of cardstock which covers the frame and is the back of the cavity where the sliders move.
3. Three 0.125-inch-thick pieces of hardboard that are the tacks for the sliders to move on. Each piece is 8.5 inches long and the widths are stated in Step 5.
4. Two sliders which are less thick than the tracks. See Steps 6 and 7 for details on the construction of the sliders. The sliders are 9.5 inches long so they are wider than the frame. The top slider has a day-of-month table and a month table. The bottom slider has a marker line.
5. The face which is made from cardstock and is 8.5 inches square. It has a line with the days of the week (SMTWTFS), a year table and the hour indications for the clock. The face is the front of the cavity where the sliders move.
6. The clock hands.

Face Template

Sliders Template

How to Use Excel to Make the Templates

The first two documents are templates that can be printed to make an exact duplicate of the face and sliders of my clock with a built-in perpetual calendar. This is a refined design that needs little, if any, improvement. The face has a SMTWTFS line, two windows, a year table and the hour marks for the clock. The top window displays seven columns of the top slider which has a day-of-month table and a month table. To set the calendar move the top slider to put the month of interest over the year of interest. The calendar in this Instructable has an optional bottom slider to put a marker over the column that has the year of interest. This slider saves having to hunt for the column that has the year of interest when the calendar is advanced to the next month.

The third document provides enough information to make Excel spreadsheets for printing the templates. Excel spreadsheets are needed only if you want to make modifications to the templates in the first two pdf documents.

Ideally, the frame is made from spruce or pine. The critical dimensions are:

1. outside 8.5 inches by 8.5 inches to be the same size as the width of a standard sheet of cardstock
2. width of gluing surface at least 0.75 inches
3. depth 1.0 inches, which must be greater than the depth of the clock mechanism

A standard spruce or pine board is 0.75 inches thick, and a piece with a cross-section 0.75 x 1.0 in. can be easily cut from it. I did not have a board available, so I used some scrap particle board from an old countertop. Although my pieces were random widths, they met the above critical dimensions. If 0.75-inch-thick spruce or pine board is available, use a table saw to rip out a piece 1.0 inch wide by 36 inches long. Cut this piece into two pieces 8.5 inches long and two pieces 7.0 inches long. Some care is needed to make these pieces as close to these dimensions as possible. What is more important is that the two pieces in each pair of pieces are the same length. For the two 8.5-inch-long pieces this is achieved by cutting two pieces that are about 9.0 inches long. Then tape the two pieces together with one set of ends lined up, and cut the pair of pieces to as close to 8.5 inches as possible. Follow a similar procedure for the pieces that are to be 7.0 inches long.

Glue these pieces together to make the frame shown above. I did not have any clamps but I found that the frame did not come apart if I just pushed the pieces together and left them while the glue set. A screw or nail can be put in each corner after gluing, but are not needed as the pieces that are glued to the frame in the steps below provide adequate reinforcing.

Measure the frame to check how close the dimensions are to the desired 8.5 inches high by 8.5 inches wide. If the dimensions are within plus or minus one-thirty second of an inch, they can be regarded as exact. If the dimensions are one-sixteenth to one-eighth inch high or low, the cardstock sheet in Step 3 and the face in Steps 4 and 8 will noticeably not fit well. Some things that can be done are:

1. If a dimension is less than 8.5 inches, the cardstock sheet and the face can be trimmed to fit the frame.
2. If the height of the frame is more than 8.5 inches, the heights of the cardstock sheet and the face can be made longer than 8.5 inches to fit the frame.
3. If the frame is wider than 8.5 inches, it is wider than the fixed 8.5-inch width of the cardstock sheet and the face. In this case the frame can be trimmed by passing through the table saw to be a width of no greater than 8.5 inches.

When the cardstock sheet or the face has to be trimmed to fit the frame, this can be done before gluing or the overhang can be cut off after gluing.

This sheet is the back of the cavities where the sliders are. It is 65-lb. cardstock with nominal dimensions 8.5 in. x 8.5-in. Before cutting to size, check the measurements of the frame made at the end of Step 2, and make adjustments as needed. Use a small brush to apply glue to the frame. Put a heavy book on top to apply some pressure while the glue sets. See Step 5 for a photo that shows the cardstock after the tracks have been glued to it.

Although the face is not glued in place until Step 8, it has to be printed and cut out at this point to determine the distance “X” for gluing the middle track in place. Use a laser or ink jet printer set to its highest dot density (most common is 1200 dots per inch) to print the pdf document “Template for Face” on 8.5 x 11-inch 65-lb cardstock. The width of 8.5 inches is the desired width. The height of the face has to be trimmed at both the top and the bottom to be 8.5 inches. As for the cardstock sheet in Step 3, these are nominal dimensions and they may have to be adjusted to fit the frame. Where to cut for the height is determined by drawing a horizontal line at the top and a horizontal line at the bottom. The lines must be 8.5 inches apart (or slightly less or slightly more according to the measurements of the frame) and located so that the face is centred between them. Draw the lines before covering with laminate because a visible line cannot be drawn on laminate with a pencil

After drawing the two horizontal lines, cover the face with a self-adhesive laminating sheet. The easiest way to do this is to peel the backing from the laminating sheet and lay the sheet on a flat surface with the sticky side up. Then lay the cardstock on top of the laminating sheet. Covering the cardstock with a laminating sheet is essential to give it more rigidity and more resistance to wear.

Using a utility knife and a metal straight edge, cut along the lines that are 8.5 inches apart and cut out the two windows. The top window is the rectangle below the line that has SMTWTFS, and the bottom window is the rectangle above the year table. Use an old magazine as a cutting surface. As the pages get cut up, tear them off and throw them away. Self-healing cutting surfaces can be purchased from craft stores, but I have found that an old magazine works well.

The photo shows the tracks after they have been glued to the 8.5 x8.5-inch blank cardstock sheet. (I used an old sheet that had some printing on it.) The first step is to cut the 6 x 9-inch piece of hardboard into a piece that is the width of the frame (which is nominally 8.5 inches) by 6 inches high. This is achieved by setting the frame next to the blade on the table saw and adjusting the rip fence so that the frame is pushed against the blade. Then remove the frame and push the hardboard through the saw. Cut the resulting piece into three pieces with heights of 3.125 inches, 0.875 inches and 1.375 inches. These dimensions can be off by one-sixteenth of an inch as the heights of the sliders are adjusted to fit the spaces between the sliders.

Before gluing, draw a line to locate the top edge of the middle piece. The line is a distance of “X” from the top, where “X” is the distance from the top to the bottom of the top window. Use the face that was cut out in Step 4 to determine the distance “X”.

Using a small brush apply, glue over the entire back surface of the 3.125-inch-wide piece of hardboard and set it at the bottom of the blank cardstock. Wipe away any glue that oozes out of the edges. The top edge of this piece is the bottom track for the marker, and wiping away glue from this edge is especially important.

Apply glue over the entire back surface of the 0.875-inch-wide piece and set it in place so that the top edge is along the line drawn above. Wipe away excess glue.

Apply glue over the entire back surface of the 1.375-inch-wide piece and set it in place so that the top edge is at the top of the blank cardstock. Wipe away excess glue.

After glue has been applied to the three pieces and they have been set in place, put a heavy book on top to put some pressure on them down while the glue sets. Make sure that none of the pieces move when putting the book on top of them.

At this point, the edges may not be perfectly smooth due to the edges of the cardstock and track not lining up exactly with the edges of the frame. The edges can be passed through a table saw to trim off one-sixteenth of an inch or less.

The procedure for printing, marking, covering with laminate and cutting out is similar to the procedure for cutting out the face in Step 4. The template orientation is landscape. Depending on the type of printer you have, you may have to specify the orientation when setting up to print. If you do not do this the printer may print in portrait orientation and cut off the right-hand part of the sliders Before covering with laminate, draw lines for the lengths and heights. Each slider is 9.5 inches long and the printing is centred along the length. Make the height of each slider about one-sixteenth of an inch less than the distance between its tracks. After the lines are drawn, the sliders can be covered with laminate. Cutting to size is done in the next step.

Backing is needed to make the sliders rigid. With 0.125-inch-thick hardboard used for the tracks, the thickness of the sliders must be less than this so that they can move in a cavity that has a width equal to the thickness of the hardboard. Finding suitable material for the tracks and sliders is a challenge. The ideal material for each is 0.125-inch-thick hardboard, but the sliders must be thinner than the tracks. Three solutions are:

1. Use 0.25-inch-thick hardboard for the tracks and 0.125-inch-thick hardboard for the sliders.
2. Make the tracks thicker by gluing one or two layers of thick cardstock from a cereal box to them.
3. Use a thinner material for the sliders.

I chose the third solution. I had an empty box made from thin corrugated cardboard that had a thickness of about 0.050 inches. Sheets of corrugated cardboard this thickness are available in quantities of 100 or more, which is far too many for making a few units. The second solution has the advantage that the tracks can be built up to make an ideal fit for the sliders. However, extra work is required. If the first solution is chosen, you may want to build up the thicknesses of the sliders so that they fit snugly in the cavity. This may be easier than building up the thickness of the tracks. A complication with the first solution is that a longer shaft length is required on the clock mechanism. As can be seen in the cross-section in the Supplies section, the shaft has to pass through the layer of cardstock, the thickness of the tracks and the thickness of the face. Common available lengths are 0.25, 0.375 and 0.75 inches. The mechanism that I used has a shaft length of 0.25 inches, which was barely long enough.

If the backing is hardboard or other material that has to be cut with a saw, cut it and the cardstock with the printing to size before gluing them together. In my case, the corrugated cardboard could be cut with a utility knife, so I glued the pieces together and then cut to size. My box was shiny on one side and dull on the other. I glued to the dull side for better adhesion. Cutting the cardboard with the cardstock glued to it required several passes with a utility knife. The face of the top slider and its backing do not have to be exactly the same height. What is important is that their bottom edges line up after gluing.

Apply glue to the hardboard tracks that were glued to the cardstock in Step 5. Do not apply an excessive amount as the glue must not ooze out and cover the track edges. The bottom of the top window must be carefully lined up with the track. Note that while the track for the top slider is along the bottom of the top window, the track for the bottom slider is below the bottom of the bottom window. The sliders can be passed through to clean glue off the track edges. If this is done, wipe any glue off the sliders. As in Step 5, a heavy book can be placed on top to apply pressure while the glue sets.

Cut a groove on each side of the back of the frame for the wire for hanging up the clock. Make the grooves between one-sixteenth and one-eighth inch deep and 2.25 inches from the top. The width of the groove can be the width of a table saw blade. Lay the wire in the grooves and use a mixture of glue and sawdust to hold it in place. Alternatively plastic wood filler or epoxy can be used.

If you do not have a piece of 16-gauge iron wire some alternatives are:

1. Use wire from a metal coat hanger.
2. Install a two- or three-inch-long nail in each end where the wire would go.
3. Substitute twine or heavy string for the wire.
4. Use two D-ring picture hangers.

Although most clocks are hung from the wall with one hanger, I suggest using two hangers for this clock due to the centre of gravity changing with the positions of the sliders.

A hole has to be drilled in the middle of the face for the clock shaft. There is a risk of the laminate tearing when a hole is drilled through it. Therefore, use a utility knife to cut away the laminate where the hole will be drilled. Drill a hole 0.125 inches in diameter before drilling a hole equal to the diameter of the clock shaft. Select the diameter of the hole for the clock shaft such that the shaft fits snugly. Details on how the clock mechanism is held in place depends on how the mechanism is made. My mechanism has nothing on the shaft or the body for holding it in place. Therefore, a thin layer of caulking or thick glue has to be put under it, or a bead of caulking has to be put on each side of it. As I was only interested in demonstrating the concept and the shaft fit tightly enough to hold the mechanism for a test, I did not bother to use any caulking.

After the clock mechanism is in place, put on the hands, install the battery and set the time. Nail two brass-plated traditional picture hangers about 5.5 inches apart on a wall for hanging the clock. As the top slider will have to be moved every month, try to locate the clock at a height where it can be easily reached. The instructions for use are:

1. Move the lower slider so that the marker is over the column that has the year of interest.
2. Move the top slider to put the month over the marker. Note that, except for January common year, each month is in two different columns in the month table. Select the column that will display the “1” in the day-of-month table.
3. Use the bottom row of the month table for January and February in common years and the top row for leap years. Leap years are bold.
4. Ignore 29, 30 and 31 when applicable.

The bottom slider enables locating the column with the year at the beginning of the year and not having to search for it each month. If this slider were not there, the first two instructions would be combined into one which would be “Move slider to set month over year.”

In the year table, the day of the week that January 1 is on determines the column the year is in. If you imagine that the columns 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 of the week that January 1 falls on.

In addition to displaying the current month, the built-in 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 May over the year column that contains 2030, 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 17 under Sunday 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 17 under Saturday. The years under May are 2003, 2008, 2014 and 2025. This is 2025, and you thought that the occasion was only five or six years ago, but it must have been 11 years ago in 2014.

Although my clock with a built-in perpetual calendar is a prototype and not a finished piece, it proves that a calendar can be added to a clock without increasing its size. The calendar is a novel and useful extra. Some changes that can be made in the construction are:

1. Glue a sheet of heavy cardstock behind the face to make it more rigid.
2. Use 0.125-inch-thick hardboard for the sliders and build up the thickness of the tracks as noted in Step 7, or use 0.25-inch-thick material for the track.
3. Use A3 size cardstock (which is approximately 11 x 17 inches) for the face and sliders instead of 8.5 x 11 inches. This would enable making a clock that is larger than 8.5 inches square. It would also enable making the face a light colour instead of white. (When printing on a 8.5-inch-wide sheet, the colour cannot go right to the edge.) The printing would have to be done at a printshop.
4. Consider using a plywood face. The year table would have to be printed on cardstock and glued to the face. The clock numbers and the SMTWTFS line could be painted on the face. The tables on the slider are too small to print on wood. A plywood face would look nice, but printing on the face and cutting out the window is more difficult to do than with cardstock. An easier construction would be to print some colour or simulated wood grain on a cardstock face.
5. Eliminate the numbers for hours on the face and use dots or short lines instead. This would give the clock a more contemporary look and simplify printing on a wood surface.

In conclusion, a perpetual calendar is a useful addition to a wall clock which I hope craft shops and manufacturers will include in some of the clocks they offer for sale.