1/2 Scale "model" windmill

[arizonian]

Welding Positioner

Early on I discovered that my welding skills are not what they used to be and I needed a welding positioner. I don't have many photos of the build so this is the description.

A DC treadmill motor supplies the power to turn a Ford front brake disc and hub bearing. There is a carbon block against the back side for the ground. The small lathe chuck is threaded on a 1-1/2"-8 spindle that is bolted to the front of the disc.

The drive between the spindle and the motor is a 3/4-10 UNC all-thread turned down on each end and is supported by two bearings that have a machined fit on either end of the "drive tube". The "drive tube" is cut away to allow access to the opposing gear. The all-thread acts like a worm against a worm gear and will adequately drive one direction but balks when choosing the opposite direction. The connection between the worm and the motor is a piece of rubber tube (air hose) with no clamps on either piece. The voltage source for the treadmill motor is a battery charger and a $10 digital speed controller. Getting the polarity backwards will let out the magic smoke on the controller.

The plastic gear was an experiment to see if a larger worm gear could be hobbed out of steel or aluminum. A 3/4-10 tap was chucked in the lathe and the gear was held by a special fixture on the toolpost.

On edit: Lube for the worm gear is Fluid Film.

More to come.
Attached Thumbnails

[arizonian]

Gearing

Way back when, maybe in the late teens or early twenties, Aermotor discovered that a windmill pump that is back geared will pump water in a lighter wind. I believe that this is what led Aermotor to outsell their competition after only a few years on the market.

The very first thing that physically happened on this build was torch cutting two discs from 3/4" plate, truing them up and them mounting them in a dividing head and gashing the teeth. The decisions prior to the torch included how many teeth on each gear and what was the available gear cutter in my shop. After many searches, sketches (Paper Aided Design), and inventories, one of the cutters needed was already on hand and the other cutter could be ordered.

The Terms (And some math):

Diametrical Pitch (DP) is the number of teeth on a 1" circle AT THE PITCH DIAMETER.

Pitch Diameter (PD) is the diameter of the gear at it's approximate centerline.

To find the outside diameter, add two (2) teeth to the number of teeth (N) and divide by DP. In the case of the bull gear, (46+2) / 8 = 6". In the case of the pinion, (14+2) / 8 = 2". Beautiful! Torch in hand, the blanks were cut.

An early mistake was to not key the two gears together. They were held by together by socket head screws and them keyed later. Now that the pinion cutter is on hand, they will be keyed together before gashing.

The ratio of the pinion to the bull gear 3.286, so ~3-1/4 turns of the sail wheel to the pumping action.

More to come.

[arizonian]

The Tower

Since the pinion gear cutter was not on hand, work commenced on the tower. Fifteen feet was the height chosen for the tower with the wheel centerline no more than another foot. The tower build is basically cutting and drilling holes, general structural construction, so nothing really exciting.

Photos of my sketches do not show the details involved.

More to come.

[mtblah]

Impressive math skills !
You lost me when you used "dirty" words like sine .
I just looked at the pictures ............

[Windcatcher530 Dan]

Very nice work William but to technical for me i never made it to the college of knowledge. But I can educate you on one of your statements. Aermoters first windmill was back geared 1888. There first oil bath was 1915 also back geared.

[arizonian]

Thanks for the info, Dan.

[arizonian]

The Motor

While technically not a motor, the gearbox is colloquially referred to as a motor since it directly drives the pump. Many pieces to the motor are still being worked on.

The wheel shaft is off center of the slewing shaft (mast). When the wind picks up to an excess speed, this gives a moment arm or torque to turn motor out of the wind. The job of the tail is to keep the motor in the wind, so there is a self regulating battle between the two. More on that later.

The gearing determines the spacing between the wheel shaft and the bull gears. Once the parts were partially machined, the parts were fixtured and welded together, then dropped onto the mill for final boring. The boring had to be done at this stage since the outside of the motor case will preclude access to the bull gear bore.

The motor case has been started. The snout that will support the wheel will be a mechanical connection to the case. A pilot will be bored to ensure concentricity with the pinion bearings. Snout is positioned in a mockup state.

The exterior of the motor case is a 6" thinwall pipe that has had the tangents flattened on an anvil.

More to come.

[Smax]

Great work

[arizonian]

CAD ( Cardboard Aided Design)

[arizonian]

Water testing. Lunch first, check for leaks and repair if necessary, then head over to the machine shop. If it don't hold water, it won't hold oil.