Grunting & Lifting 101 Training for ChristmasComments (0)
This article is from Issue 7 of Woodcraft Magazine.
Automata – intricate wooden devices that spring into motion at the turn of a small handle – are among the oldest of toys. This one takes a whimsical look at how a certain jolly old elf might get himself into shape for the big night.
Contemporary automata are hand-cranked wooden mechanisms that animate a miniature scene. This automaton features Santa Claus performing “dips” – an exercise that strengthens the triceps, chest and shoulders. Santa will need these muscles to go up and down chimneys on Christmas Eve.
While the exquisite clockwork automata of the 18th century made every effort to represent people and animals accurately, there is no taboo today against showing the linkages that make the automaton move. Likewise, the carved figures in contemporary automata are more humorous than realistic.
I use brass and wood as the principal materials in my automata because they have an antique appearance. I tend to hide more modern-looking material types, but this is a matter of personal preference.
The box unit that holds the mechanism isn’t usually enclosed, for a very simple reason: People are sometimes more interested in the mechanism than in the animated figure.
For the box, rip a 24" piece of 3/4" cherry stock to a width of 3". Use this workpiece to cut top and bottom pieces to 61/4", and the two sides to 51/2". I chose to use dowelled butt joints for this piece, because experience has taught me to use joints that can easily be assembled and disassembled many times during construction.
Start by drilling a pair of 3/8" holes into the ends of each side piece − eight holes total − to a depth of 3/4" (Fig. 1). A drill press vise or a vertical drilling jig like the one shown here is essential for perfectly vertical holes. Use dowel centers to locate the corresponding holes to be drilled in the top and bottom pieces of the box (Fig. 2). Drill the matching holes, insert dowels, and mark each corresponding corner for ease of assembly (Fig. 3).
Locate the center of the top face of the box top, and drill a 25/64" hole all the way through. This hole will allow a 3/16" brass rod attached to the movement piston to pass through the box top and into the underside of the figure.
Dry-fit the box, but don’t glue it up yet.
Making the mechanism base
The automaton’s mechanism converts the rotary motion of a crank and circular cam wheel into a reciprocating up-and-down motion of the piston rod attached to the Santa figure. Santa’s arms are hinged at the shoulder, elbow and wrist. Because his hands are fixed to the parallel bars, when the body moves up-and-down the arms bend at the joints, giving the illusion that Santa’s getting some serious workout time.
Cut the outline of the mechanism base to shape on a bandsaw or scroll saw, then drill out the circular well for the cam wheel. Use a 17/8" Forstner bit to drill to a depth of 1/2" (Fig. 4). A Forstner bit of this size is pretty aggressive, so be sure to clamp the mechanism base securely to your drill press table.
Next, clamp the mechanism in an upright position to drill the vertical piston shaft. Use a 25/64" drill bit to drill a hole from the top of the piece down into the cam well, positioning it so the edge of the hole is 1/8" from the front face of the mechanism base. This hole should line up with the one in the box top.
A slot on the front face allows a pin to connect the pushrod to the piston. To cut the slot, I used a table saw with a standard 1/8"-kerf blade. Place the mechanism base facedown on the table saw and raise the blade just high enough to enter the piston shaft you just drilled. Center and hold the base against the miter gauge with stop blocks, and mark a stop line on the table saw throat plate so you can end the cut as soon as the blade has entered the cam well (Fig. 5). This is a little tricky, so take it nice and slow. If you’re uncomfortable with this operation on the table saw, you could also cut the slot with a metal straightedge and a sharp utility knife.
Cut a piece of cherry to 3/4" x 3/4" x 3". This piece mounts on the back of the base mechanism, doubling the thickness of the wood surrounding the axle, and acts as a bearing for greater support and a smoother cranking action. Center and glue this piece on the back of the mechanism base, with one end flush with the bottom of the base.
Use the center dimple created by the Forstner bit as a guide to drill a 25/64" axle shaft hole through the base and the middle of the bearing. As always, it’s wise to back up the piece to be drilled with some scrap wood to prevent tearout. The completed mechanism base should look like the one in Figs. 6a and 6b. Finally, drill a pair of 3/8" holes on the underside of the base, and use dowel centers to mount the mechanism base to the box bottom so it aligns exactly with the hole in the box top. This is critical for the free movement of the piston rod.
Glue the base mechanism in place, then assemble and glue the box unit together around it, clamping it till dry. Sand the entire box up to 220-grit, and apply a coat of Danish oil. Wipe off the excess, and allow it to dry.
The actual mechanism consists of a cam wheel, axle, pushrod, piston rod, crank and crank handle. Create each in turn, and put aside until time to assemble everything.
First, cut a 13/4" cam wheel from a 1/2"-thick piece of cherry, and true it up on a disk sander. (The wheel can also be cut with a fly cutter.) Drill a shallow 1/16" hole about 1/16" from the center of the cam wheel to serve as a starter hole for the #16 escutcheon pin that links the cam to the pushrod.
Drill a 3/8" hole through the center of the cam wheel to accept one end of the axle, a 21/2" long cherry dowel. Glue the dowel in place. The cam wheel/axle assembly should fit smoothly into the cam well as in Fig. 7.
Cut the pushrod arm to shape on a bandsaw, scroll saw or by hand. Again, use a 1/16" drill bit to create the holes in both ends of the pushrod.
The piston itself is a 1" section of 3/8" cherry dowel slightly rounded at the ends. Drill a 3/16" hole in the top end of the piece to accept a 51/4" brass rod that connects to Santa’s belly. Round the ends of the rod slightly with a grinding wheel or stationary belt sander, then tap it gently into the end of the piston. Drill a shallow 1/16" hole in the base of the piston to act as a starter hole for a #16 escutcheon pin (Fig. 8).
The crank arm is a 3/4" x 3/4" x 21/4" piece of cherry, with 3/8" holes drilled partially through opposite faces on each end. Glue a 2" piece of cherry dowel into one of the holes for the handle.
Assembling the mechanism
A small wooden peg keeps the cam wheel/axle mounted within the mechanism base. Insert the main axle through the front of the mechanism base to seat the cam wheel into its well, and mark the axle where it meets the bearing. Remove it and drill a 1/8" hole in the axle shaft so it just touches the mark. Return the assembly to the mechanism base, and slip a short piece of 1/8" cherry dowel into the hole to hold the assembly in place (Fig. 9).
Slide the piston rod into its chamber. To connect the pushrod to the piston, slip a #4 brass finish washer over a #16 escutcheon pin, then pass the pin through the face of the pushrod into the hole in the piston. Connect the other end of the pushrod to the hole in the cam wheel in the same manner. Tap both escutcheon pins in place, but not so tightly that the parts won’t move freely (Fig. 10).
Grab the axle with your fingers and give it a few turns. The piston should bob up and down in the vertical shaft. If it doesn’t move freely, disassemble and use sandpaper to smooth down the offending part.
When you’re satisfied that all the components are operating smoothly, finish with Danish oil as before, then reassemble. Glue the handle in place on the end of the axle.
Carving Santa into shape
The Santa figure is carved from a piece of basswood measuring 2" x 3" x 6". Apply the profile pattern to one of the large faces using carbon paper, or by transferring a photocopy of the pattern by taping it face-down on the wood and rubbing the paper with a rag soaked in a bit of lacquer thinner.
Drill relief holes close to the figure at any tight interior curves, then use a scroll saw, coping saw, or bandsaw to cut along the front of the figure. Try to keep the waste in a single, intact piece. Repeat this process for the opposite side of the figure until the entire profile of the figure has been cut out.
Use masking tape to reattach the waste pieces to the front and back of the figure, giving you flat, square faces once again. Turn the block so Santa is facing up, and apply the front pattern, lining it up with the pattern you used on the side.
Carefully cut the front outline (Fig. 11). Remove the masking tape and all of the waste pieces to reveal the rough-cut figure.
Before you start carving, pencil a centerline on Santa (Fig. 12), then draw a series of small rectangles to outline the high spots of the head – face, nose, ears, mustache and beard (Fig. 13). Avoid these areas until you have removed the lower areas first. For detailed areas, use a sharp knife to outline shapes, and then carve from within the waste areas – the lower contours of the face – to those lines (Fig. 14).
Once the pencil marks have been carved away, consult the diagrams and photos, evaluate, and draw more pencil lines as needed. By alternating between drawing and workpiece, you can progress to the finished carving.
When rounding the corners around the body, be sure to leave smooth, uncut surfaces at the shoulders where the arms attach. These flat faces will keep the figure from twisting as it moves up and down.
Check your work frequently with light coming from various directions and while holding the figure at various angles. This will help you keep the figure symmetrical.
Carve a thin line down the center of Santa’s chest and belly to represent the seam of his shirt, then use a large nailset to press a few buttons into the wood on one side of the line you just made.
Adding the arms
The arms are built in four pieces – the upper arm, forearm, wrist tenon and hand – all connected to the body and to each other by escutcheon pins (Fig. 15).
Make all of the escutcheon pin holes a bit larger than the escutcheon pin except for the one furthest from the pin’s head. This allows the parts to rotate freely around the pin, but anchor securely to prevent the pin from falling out.
Cut the arm pieces according to the pattern. Test their fit with the elbow pin in place and use a needle file (or an emery board) to round and smooth the joint pieces.
Drill a shallow 1/4" hole in the ends of the forearms to accept the wrist tenons (Fig. 16). The tenons are made from a short length of 1/4" dowel, with one end sanded or carved flat to form a tenon that fits into the slots at the back of Santa’s hands. These, too, are attached to the hands with an escutcheon pin that acts as a pivot.
Belly up to the bars
The parallel bars consist of a wooden base, four brass rod uprights, and two 1/4" hardwood dowels. I had a piece of 1/2" aspen that I used for the base of the parallel bars that I cut to 25/8" x 51/2", but any light-colored wood works just as well. Drill four 1/8" holes in the corners of the base, and a 13/16" hole in the center that will line up with the hole in the top of the base unit.
Cut four pieces of 1/8" brass rod to a length of 23/4". Slightly round the ends of each rod and tap them into the base holes.
Cut two hardwood dowels to about 6". Hold them on top of the brass uprights, and mark the location of the mounting holes (about 1") in from each end), then carefully drill about half way into the dowel with a 1/8" bit. Fit each dowel over the upright rods, and tap them gently into place. When glued in place atop the box unit, the finished parallel bars should look like those in Fig. 17.
Assemble the arms and mount them to the body with escutcheon pins. Remove the parallel bars and slide the hands into position, then reattach the parallel bars. Making sure that the piston is at its lowest point and that the figure’s arms are folded, move the figure forward until the brass rod touches the figure’s belly, and mark a spot about 1/2" below where the rod touches the figure. View the figure from the side, and draw a line that shows the orientation of the brass rod and, thus, the hole. Use a 3/16" bit to drill a hole no more than 1/4" deep. Assemble the figure and see if it moves through a full range of motion. If not, make the hole deeper until you’re satisfied with the range of motion.
At this point, the construction of the automaton is complete. Assemble all the parts, and make sure it works. If anything does not turn smoothly, now is the time to pinpoint the source of friction and eliminate it.
A colorful conclusion
Remove Santa and give the entire figure a coat of quick-drying sanding sealer (Fig. 18). This seals the relatively soft basswood, allowing you to carve smaller details and sand without creating a fuzzy texture to the wood.
As a base for the paint to follow, I apply a coat of acrylic gesso to the areas that will be painted: the hat, hair, beard, body, arms, shorts and boots (Fig. 19). A short length of brass rod makes a great holder for painting.
I used artist’s acrylic paints for the areas that are red, black, gray and white. Mix a bit of black with the white to make a light gray for his shirt (Fig. 20).
Use a fine detail brush or the edge of a toothpick to draw stripes on Santa’s shorts with some red paint (Fig. 21).
Once two coats of paint have been applied, use a very sharp knife to trim off any paint that has accidentally ended up on the face and legs.
I used an old soldering iron with a brass tip to burn in Santa’s squinting eyes, but they could also be painted, carved, or drawn on with a finetipped marker.
Finally, give the legs, face and hands a second coat of sanding sealer.
When all the paint has dried, reassemble everything one last time. You may find that after all the repeated assembly and disassembly, that you need a small drop of cyanoacrylate glue to hold the various escutcheon pins in place. Use as little as possible, and don’t glue any moving parts together!
Projects like this are open to a number of variations. For example, you can use a different type of joint for the box, or even a different configuration so long as the inside dimensions remain the same.
Adding a base to the box adds weight and stability. It’s also a great place to put a plaque with the title of the piece and your signature.
Of course, Santa’s workout outfit can be painted any way you like. And if you aren’t squeamish about drilling a hole in the top of Santa’s head, you can easily convert the figure to do handstand push-ups.
Dug North designs and makes original wood automata at his home studio in Harvard, Mass. His work has found its way into collections of automata both large and small. See more of his whimsical creations at www.dugnorth.com.
TOOLS USED IN THIS PROJECT
Table saw, drill press, 3/8" dowel centers, bandsaw or scroll saw, 17/8" Forstner bit, clamps, glue, sandpaper, disk sander, carving knife, masking tape, nailset, needle file or emery board, soldering iron
Brass piston rod 3/16" x 51/4"
Brass rods (4) 1/8" x 23/4"
Brass escutcheon pins (6) 1" x #18
Brass escutcheon pins (2) 5/8" x #16
#4 Brass finish washers (2)
Acrylic paint – red, black, white
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