My next Windmill
Made with mostly locally found hardware store parts.
This is a work in progress and I am trying to
simplify it and make it better.
Suggestions from anyone building and making improvements to this design are welcome.
Constructive criticism is appreciated too, although it may not seem like it.
Above left is the mill flying without the alt in a test. Left is an early partial showing of the bits.
Above is a 1 1/4 to 2" PVC bushing with the race from the bearings set into it. The lower part of the bushing has been cut to eliminate a lip. The race had to be fitted in with a thin piece of sheet metal wrapped around it to hold the race securly.
This is the main bearing assembly. Critical to this design is the length of the 1 1/4 PVC pipe in the middle. Here it is cut to 4 5/32". I cut it long to begin with and then I would fit everything together and hand tighten the nuts on the end. If the bearings did not spin freely I took it apart, shaved a hair off the PVC pipe and refitted until I could tighten the nuts and the bearings still spun freely but with no slop. On each end you can see the brass colored bushings. They had to be sanded a little bit in order for the tapered roller bearing to slide on snug. When the whole thing is fitted together and the jam nuts fastened tight, the bushings should butt hard together so that threaded rod, jam nuts, and bushings all turn as a unit without any part slipping and turning on the threaded rod. The length of the PVC pipe in the middle makes sure the bearings turn freely but without any slop. Note the 2" by 1/16 rubber O ring. It's purpose is to keep the bearing races from laying flat against the PVC bushing, otherwise the bearings will rub on the PVC bushing.
This is the heart of my mill and although it's not too complicated it must be precise. Tightening the jam nuts on each end must lock the brass bushings, keep the bearings snug but turning free and not be TOO TIGHT. If the jams nuts are tightened too hard it will cause the treaded rod to bend!
Above left, a PVC cap with a 3/4" hole drilled to accept the threaded rod. This serves as a front bearing cover. On the right the bearing assembly attached to a floor flange with muffler clamps. Note - the close nipple directly below the floor flange should be schedule 80. Using schedule 40 is an accident waiting to happen. The pipe is simply too weak at the threads and in time WILL fail.
Left you see the PVC toilet flange that will support the stator bracket. This PVC flange is a weak point and is reinforced in the photos below.
Bench testing a coil. I attached a
strobe disc to the rotor and could check RPM's under a fluorescent light. At 150
RPM I was getting 1.65 volts. So, doing the math,
1.65 X 3 = 4.95, then 4.95 X 1.732 = 8.57, then 8.57 X 1.4 = 12 volts
So, I estimate cut in for charging a battery at 12.8 volts, allowing for losses will be in the neighborhood of 170 to 180 RPM.
Above right, a rubber washer cut from an old inner tube. This is fitted between the end of the bronze bushing and a flat washer. On the right, it rests against the PVC bushing to create a protective barrier for the bearing located behind it. This was changed, a few days next to the oil and grease of the bearing made the rubber shrivel and wilt. I cut a new protective washer from a piece of thick vinyl.
Reinforcing the stator support. This is 1/8 " aluminum sheet cut with a saber saw and bolted with SS bolts like you see.. All PVC fittings and pipe on the stator side get glued. The PVC bushing on the other end of the pipe need not be. Don't glue them until you have test fit them several times and are sure the center pipe is cut exact.
Above left I had to flatten the front of the floor flange. As it was when I tightened the muffler clamps the PVC bushings were forced to spread, putting pressure on the bearings and causing them to rub.
Here you can see I brought out all six points for wiring in any configuration I choose. On the right I managed to find a heat sink to mount the rectifiers on for testing. When finished I will bring all the wires down the mast and the rectifiers will be by the battery bank.
I carved these 6' blades from the guide on WindStuffNow.com. Ed there says TSR is in the neighborhood of 6. All I know is they sure beat PVC pipe. They were cut from 2 X 6 yellow pine using a sawsall and a sander.
There is no furling with this mill. To restrict speed I will be adding magnets to the second steel rotor which is now blank. This will lower cut in as well as put the mill into stall. From there I will be able to use a number of options to fine tune things including,
Adjusting the air gap
Wiring in Delta or "Jerry Rig"
Changing the number of blades from 3 to 5
The goal is not high power, but steady low wind power.
I have to say that this setup is by no means cheaper or less time consuming to build than the 4" trailer hub setup made famous by the Dan's at Otherpower, that is assuming you have their tools and skill. It is however, possible to accomplish for someone with limited tools and skills. The whole process went thru a lot of changes and will continue to do so.
Special thanks to:
And my wife.
Partial Parts List:
PVC pipe - 1 1/4" cut to approx. 4 1/8" long.
Use schedule 40 by itself or for more rigid construction use light wall PVC with
1" EMT fitted inside. (this must be custom cut to fit your contraption
2 - PVC fittings - 1 1/4 to 2" bushing
1 PVC bushing, 2" to 3 1/2"
1 PVC toilet flange (must accept the above bushing)
3/4" threaded rod. I bought a 3' piece and cut it in half
1 set of tapered roller bearings with races ( L44643 same as used on the 4" trailer hub)
2 Bronze flange bushings 3/4" id, 1" od. X 1" (Ace hardware)
2 Bronze bushings, 3/4" id, 1" od. X 2" (Ace hardware)
2 rubber O rings, 2" x 1/16"
4 nuts, 3/4"
2 Muffler Clamps, 1 1/2"
1 Floor flange, 1 1/4"
1 Schedule 80 close nipple *(use schedule 40 at your risk)
1/8" flat aluminum stock (for stator support and reinforcing)
1/4" stainless steel allthread
Lots of stainless steel 1/4" nuts, washers and lock washers.
6 - 3/4" flange nuts
Go to my old mill.