Our Bear Automaton is simple yet can excite the wonderful minds of many children. Since children are obviously our target audience our primary goal is for them to completely understand the movements of our automaton and and find enjoyment out of them. To satisfy this goal it is necessary to use simple reciprocating and oscillating movements in our automaton which is why the bear (our main character in our automaton) taps its head with its upper hand which is the reciprocating movement and rubs his belly with his lower hand which is the oscillating movement. The bear also has a tu-tu which rotates around it which adds to the childlike theme. The bear itself is 4” by 8” and it is suspended on an 11.5” by 7” wood box. We chose this particular theme because we felt that an automaton would best be reflected as a child's toy anyway and it was perfect for incorporating different movements and parts.
Step 1: Materials and Tools
Gather your tools and materials, you will need:
12” x 12” x ⅛” baltic birch plywood
12” x 12 x ¼” baltic birch plywood
Wooden dowel rods of various sizes (⅛”, ¼”)
Aluminum wire Drill press ¾” x 6” select pine wood
Pink and Green Colored Paper
Power Drill Screws Matching drill bits to dowel size
Pink and Green Colored Paper
Awl for Wood punching or autopunch
Safety Glasses or Hearing protection
Step 2: Drawing
Key points of drawing:
This point is the oscillating motion of the bear's arms that will depict the motion of the bear rubbing its belly in a circular motion. The mechanics of the motion will be carried out by a lobed cam that is attached to the crankshaft (point:G) which as it rotates presses against a cam follower which actuate push rod up and down in a reciprocating motion. This push rod will also have a thin narrow gauge wire attached to it that conveys this motion to the arms of the bear.
This is the reciprocating motion of the bears arm that will be patting the head of the bear. This motion will be carried out by another push rod (point H) will be actuated by another lobed cam I . and will be done in a similar process as point A. With the notable exception that the narrow gauge wire will run behind the bear hidden by sight.
This is the crank shaft of the automotive which will provide the mechanical power to the entire mechanism . said power will be provided by crank (point G) all the cams and roller bearings will be attached to this shaft and will receive their power from it.
This is the tutu of the bear , it will rotate around the bear following the rotary motion of the vertical roller bearing in point F.
The actual body of the bear will be made from the thinner sections of the balsa wood.
This will be the mechanism that supplies the rotary motion for the tutu in order for it to spin around the bear. It will be made up of a single non lobed centrally stationed cam that will act as against roller bearing cam that will create the rotary force against a shaft that will in turn spin the tutu.
This will be the push rod and follower assembly that acts with a cam attached the crank shaft the moves the arm up and down in reciprocating motion to pat its head.
Step 3: Stencils and Drawing Out
The first step in the the build process is to transfer your design from the page to the real world , and to start that first we must draw or trace out the shape and components of the prototype on the wood. I would recommend breaking up the components of the actual design so it's easier to modify or make changes to your design as you go along instead of having re cut the entire project. Once you have traced out all the the pieces of the design . re-assess them and make sure that they laid out the most practical manner to cut. It would also be a good idea to see if the fit in the real world rather than on the 2d dimensional paper so use common sense.
Step 4: Cutting the Shapes, Gears, Dowels and Cams
Begin to cut out the the shapes from the patterns that you have sketched out previously using the scroll saw. (Note* tie back your hair, remove all loose articles of clothing, wear safety glasses and be cautious.)Also you will have to make one extra cut which will be cutting a straight horizontal line across the lower midsection of the bear's stomach. Once you have done so make sure all the pieces line up so they can be assembled later on. Next you want to measure and cut the dowels for the crank shaft and the push rods (this can be done using a . Making sure to not overstress the wood as they are prone to snapping. Once you have the done,cut out the cams and sand them down to as close to the desired shape as you want , in our case we were making the lobed cams out of the circles from a boring bit on a drill press. After achieving the desired shape , measure and mark out the point on the cam where the crankshaft will go through and attach too. Drill with the bit closest to the size of the diameter of the shaft. Lastly you are going to want to cut the thicker pieces of wood to keep the mechanism box or “stage for housing /hiding the mechanism. Keeping in mind to drill and cut the necessary holes for the motion wires and the rotary shaft for the tutu. As well as leaving a hole for the crankshaft to exit.
Step 5: Assembling/Painting the Bear
Now since all of the pieces of the bear are cut out you can now assemble it. First take the decal from step 3 and print it out. Next cut out the corresponding decal pieces but cut the bear’s stomach decal in two separate pieces so it matches up to where you cut the wood model of it. and paint them using acrylic paint matching the colors we used in the photo on the right. Once all the pieces are dry use glue to attach them to their respective piece of the bear. Next attach the head of the bear to its body by using wood glue and then also you can attach the 2 pieces of the tu-tu together using wood glue and use a clamp to hold it together as it dries as see by the figure on the left. Once these are done drying you can attach the top portion of the bear which includes its upper midsection and its head to the middle of the tu-tu using wood glue. Once that piece has dried attach the lower midsection part of the bear under the tu-tu so it matches up with the rest of the body. Then finally you can attach the bear’s feet to its lower midsection.
Step 6: Assembling/Attaching the Arms
Next you will cut out the arms of the bear using the scroll saw, the measurements for these arms can be found in the drawing from step 2. Next use the drill to drill in holes in each of the pieces of the arms corresponding to where they are in the drawing to the right.
Next place the pieces of the arm as they are in the drawing to the right and use aluminum wire to connect the pieces of the lower arm together.
Finally attach the 2 piece arm to the right hole of the bear which can be checked in the drawing from step 2 and attach the other arm to the left hole.
*Note: Also it would make the bear look much better if you were to paint these arms using acrylic paint
So they would match the color of the bear.
Step 7: Making the Frame
To make the frame you simply have to cut out 4 pieces of wood using the bandsaw. The measurements for these pieces can be found in step 2 in the drawing. After you have cut out these pieces you will want to assemble the box by attaching the pieces together using a drill and drilling in 2 screws attaching each piece of wood. After you are finished attaching all of the pieces together the frame should look like the picture on the right.
Step 8: Background and Color
This step is not a necessary step although we do highly recommend you do it because it will improve the aesthetic quality of the automaton. All you have to do for this step is trace or freehand draw grass on green colored paper and cut it out and then glue it to the front of the frame so it will be positioned in front of the bear.
Step 9: Assembly of the Gears, Cams and Dowels
First measure out the two lobed cams that are approximately 2” in diameter. Once this has been accomplished take an ⅛” diameter drill bit and place a hole approximately ¼” from the edge of the cam. This hole will serve as the point for which the entire cam rotates and allows the crankshaft to travel through and in turn deliver the circular rotary-force to said cam.
Next take the ⅛” dowel and trim one down to approximately 4 and ¾ inches, and the 2nd segment that is 3” in height. Once done with both segments, take a spare sheet of balsa wood and make two 1”x1” plates, then attach said plates to one end of each of the segments. Lastly, to finish the stage of the project, drill a 1/16” sized hole on the opposite side of the dowel that the pressure plates are affixed too. These segments will serve as the automatons push rods which will be acted upon by the lobed cams, transferring the rotary motion to that of a reciprocating up and down motion. Next cut another two circles out of the ⅛ inch balsa wood sheet, these will serve as the mechanisms gears that will spin the automaton’s tutu. To create the gear, start by cutting stringle shaped segments about a ¼” in depth from the edge of the circles and another ¼” apart from each other, this fill form the gears teeth. Next, drill a hole through the center of both the cams, these will the affixment points for both of the crank shafts. Next attach them to the automaton’s crankshaft that derives rotatory power and the other to the shaft that is affixed to the tutu. Finally mesh the gears teeth together, to produce rotary motion of the tutu. One shaft will be horizontal and the other will be vertical, keep in mind that the crankshaft itself will be the horizontal one.
*Note: When drilling, but sure to take all the safety precautions like wearing safety glasses, tying back long hair and removing any loose articles of clothing.
Step 10: Reflection
This automaton was a really great experience in terms of the whole process of making it and failing and then fixing our mistakes to the point where we could ultimately make this stress free guide to help you guys. Our favorite part of this whole process was assembling the automaton itself after we had cut out all of the pieces because it was fun to face challenges and keep making our automaton better. If we were to change something it would be to make the frame of the automaton a lot smaller because the extra space was just unnecessary and hindered us. Next time however if we were to do something differently it would be to make the mechanism that lifted up the upper hand stronger, and also smaller things such as painting the arms and adding fabric to the tu-tu.