Whirligig Plans
If you would like full size plans and material lists to any of the whirligigs shown in my blog and my Youtube Channel, [http://www.youtube.com/chuckdunbar], leave a message. They will cost $10 US.
Tuesday, February 27, 2007
Blade Hubs
I have shown the steps for making a whiriligig propeller hub with metal rod arms. (Whirligig Blade Hub, 1-26-2007) In the coming week I’m starting a whirligig the blade hub of which will have the wood blades directly attached to the hub. I’ll post photos showing each step to making the hub.
Sunday, February 25, 2007
Mechanism for Whirligig #36
Cam to Create a Wagging Circle, cam diameter 2 1/8″ (5.7 cm)
Several sketches led me to this simple mechanism for Whirligig #36. There are two problems to solve. First, the cam needs to be counter weighted (balanced) so that it doesn’t shake and not much force (from the wind) is needed to turn it. Second, how much blade surface area is required to generate the needed force to turn the cam at low windspeed. There are formulas to calculate this, but I would have to spend a lot of time reviewing math from a long, long time ago. Instead I’m eyeballing it. Weighting the cam involves changing the cam’s center of gravity so that when the linkage is in the top position, gravity acting on the descending weighted linkage provides enough force to turn the cam. Once in the bottom position, the adjusted center of gravity of the cam will raise the linkage to the top position. That is what the 1/4″ dia. brass rods inserted into the cam are doing. The drawing shows what the finished mechanism will look like. I’m going to design the whriligig so that if the initial blade arrangement is not adequate to run the mechanish, I can replace them with bigger blades. I also need to find any easy way to measure the force needed to turn the cam. Then I can begin to accumulate some data relating the force to turn the cam and the surface area of the blades. Go to my Youtube Channel to see the mechanism in motion. (Address in the column to the right.)
Wednesday, February 21, 2007
More Drawing with Edna
Untitled, 29 x 23 (74cm x 58cm), black pastel on Stathmore 2 ply Bristol
Untitled, 29 x 23 (74cm x 58cm), black pastel on Stathmore 2 ply Bristol
Untitled, 29 x 23 (74cm x 58cm), black pastel on Stathmore 2 ply Bristol
On the 16th Edna and I got together for another bout of drawing. We started by assessing the drawings we had done to this point. (The last session a couple of weeks ago was in Edna’s studio. I forgot my camera, and I forgot what drawings we did that session, so those aren’t in the blog.) We signed the fourteen or fifteen drawings we decided to keep.
Next, we talked over what theme to exploit in the next set of drawings. The last set was a variety of floating shapes, and in this set we settled on round shapes. We may keep these floating, or not. Any substantial horizontal line reads as horizon or at least serves to anchor the image to an edge of the rectilinear format. We’ll see. After warming up in the AM, we had lunch - a mixed salad with toasted and sugared pecans, pear and apple slices and a dressing of oil, lemon juice, Dijon mustard, pepper and freshly chopped parsley - we did the three drawings above in the afternoon.
I have just completed reading Visual Intelligence, How We Create What We See, by Donald Hoffman. He discusses how the brain creates images from the impulses caused by the cascade of photons falling on the retinal cells. He hypothesizes rules that govern how the neurons build the image step by step. The examples will be very familiar to artists. In these drawings I’ve been very aware of how lines meet or don’t meet, how little is needed to create the impression of a plane and so on. The images you see “out there” are not out there. They are created in your brain. What is “out there” is problematical.
Thursday, February 15, 2007
Happy Valentine’s Day
Happy Valentine’s Day
May Love’s Retriever Have a Soft Mouth
Whirligig #34
Whirligig #34, 16 1/2 x 20 x 9 (40.6 cm x 50.8 cm x 22.5 cm),
aircraft plywood, mahogany, aluminum & stainless steel hardware, sign paint
Whirligig #33
4 BLADE
DOUBLE HUB OPPOSING ROTATION
Unique Blade Design Gives Two Different Colors Depending on View Point
Four Bearings
and
ZYPHER RATED*
*BLADE MOVEMENT WITH 2 MPH WIND
Monday, February 5, 2007
Whirligig #34 Steps to Make
From the drawing I transfer the measurements to the 1/4″ aircraft plywood, which will be the vane, and drill the openings for the blades with a beam circle cutter.
I have drilled all the holes that allow me to cut out the spaces for the hubs and axles. The holes make it easier to get neat cuts. For the long cuts, I put the vane on the table saw and raise the blade. For the smaller cuts I use a saber saw with a metal cutting blade. The small teeth in the metal cutting blade don’t tear the plywood.
Here I have completed the vane, which, as in many of the preceeding whirligigs, also holds the hubs. There will be two hubs and two sets of blades in Whirligig #34. The blades on each hub will be semicircles that will fill the central opening in the vane, but only half fill the openings at the top and bottom. The small tabs on the right of each circle will fit into slots on the mast.
This is the block of wood from which I will make the eight semicircular pieces that hold the axle in the vane. I drill the holes for the #8 bolts in advance of cutting the circles. The 1/4″ groove is where I will locate the 1/4″ pilot drill for the circle cutter. I have already drilled a smaller (3/64″) pilot hole at the center of each block. The plywood of the vane is 1/4″, so the groove also gives the location for cutting the two semicircular pieces from the circular piece as seen in the photos below.
Here are the pieces including the two hubs after cutting with the beam circle cutter, cutting off the excess on the band saw (The circle cutter is actually a hole cutter and leaves a triangular cross section around the circular blocks, which I rough cut on the bandsaw.) and sanding with the drum sander to the left. I put a length of 1/4″ dowel through the hole left by the circle cutter’s pilot drill. I then put the dowel into a scrap piece of wood clamped to the drill press table. This jig allows me to easily sand to a perfect circle. The axle is 1/4″ in diameter, which is the same as the thickness of the plywood vane, so there are no more measurements and adjustments to be made.
Here are the eight finished blocks that will hold in the axles, four for each axle. They will line up with the hubs, which are the same diameter.
These are the rough cut blades. I lay out the blade ovals on a single piece of plywood, and cut a 3/16″ wide by 3/32″ deep groove that will accommodate the 3/16″ diameter rod holding them to the hub. The blades will be at a 45 degree angle to the vane. Directly from the side, front and back of the whirligig, the oval blades will appear as a circular disks. From other directions the blades will appear as ovals of constantly changing length, adding to the visual interest.
