|From the pages of Fine
Building a Shaker Wall Clock
Choose your movement first, then build the clock around it
I have no qualms with historical accuracy, except when it comes to techniques that may have worked in the past but are not suitable today. Wood movement is one of those areas. The Shakers did not have to deal with forced hot-air heat. We do. Shaker clock makers built their cases to fit their mechanisms. We must build our cases to fit mechanisms that are commercially available today. To me, that seems perfectly aligned with Shaker ideals.
For starters, the original clock was constructed predominantly of white pine. I chose cherry for its color, hardness and grain. Because cherry moves more than white pine does, I had to make a few dimensional adjustments to allow for wood movement of the back panel. Second, I decided to use a top-of-the-line mechanical movement, which required a small amount of additional interior space. Consequently, my overall case is a little deeper, and the back is a bit thinner. So much for historical accuracy.
Make the case to fit the clock parts
I never start construction on a clock until I have the movement, dial and hands (see A movement for every price range). Having these at the ready makes it much easier to fit the dial and allow proper clearance between the shaft, the hands and the glass, as well as the clock movement and the case back. I hate surprises.
Once you have the clock parts, you can cut the sides of the case to size. Then cut 3/8-in. by 1/2-in. rabbets to accept the back. The front of each side receives a stopped rabbet to accept the face. You could simply make the clock an inch wider and avoid cutting rabbets in the front, but -- for reasons more aesthetic than historical -- I prefer to keep proportions closer to the original.
On the original, the top and bottom were merely nailed onto the sides. I use long, thin screws and plugs. Another alternative is dowels. I once had a student who attempted to use sliding dovetails, only to discover that they lasted from 12 until noon. With only 9/16 in. of overhang on the sides and part of that cut away by the rabbet, the remaining end grain is extremely fragile.
I prefer to use a false bottom and top, which not only make glue-up easier but also act as a doorstop in front and create rabbets to house the back. Glue the false top and bottom to the sides using butt joints. Once the glue dries, center the actual top and bottom on the case and screw them into the sides.
Another change I make is to increase the size of the hanger hole, from 1/2 in. to 1-1/8 in., to allow the clock to be hung on a Shaker peg. The back is merely nailed into place, with a dab of glue in the center to ensure that wood movement is equal in both directions.
At this point it pays to plan ahead. Measure the depth of the movement to check that you have proper clearance for both the shaft and the glass of the door. Mechanical movements are either attached directly to the back -- as I've done -- or sit on a shelf. Quartz movements, being much shallower, are usually attached to the dial. If you use a spacer, the movement can also be attached to the case back. Planning ahead allows you to position the dial so that the hand shaft is close to the glass but does not touch it. Once you've established the location of the dial, glue two vertical filler strips to the inside of the case. Thick metal dials like the one I used can be screwed to these strips directly, while thin metal or paper dials should be adhered to 1/4-in.-thick plywood backings.
The doors are relatively straightforward, mortised and tenoned at each corner (see Door-joinery details). Cut haunched mortise-and-tenon joints on center, and make sure to offset the glass and panel grooves to allow room for the thumbnail profile along the fronts. The frames are 1/2 in. thick, and the bottom panel is only 3/16 in. thick. The 3/16-in. quarter-round moldings are added after the panel is in place. On the top door, add the quarter-round moldings to hold the glass on the outside, and add 3/16-in. glass supports, nailed from the inside, to hold the back of the glass.
When hanging the clock from a peg board, carve a 1/2-in. flat spot at the top of the peg where it meets the hanger, leaving a slight ridge, to keep the clock from sliding forward on the peg. If the peg board is 3/4 in. thick, use a 3/4-in. spacer behind and near the bottom of the clock. A toggle bolt or similar anchor will attach the spacer to drywall or plaster if there is no stud nearby. Once the clock is perfectly plumb and running smoothly, drill a hole through the back into the spacer and anchor the clock with a screw. This keeps it from shifting during winding or an accidental bump.