DC Motor Generator Section

Morse-Code | home

(June 18, 2009)

After doing some extensive research, (No not at a library, on the web! Who needs libraries when the internet is full of information?? Technology improves, mankind loses its place in the world.) Anyway, I see a lot of people are using the AMETEK brand of DC PM Motors (which are now rare and very expensive on ebay!), and some brands of PM motors that come out of treadmills. A lot are rebuilding alternators, and designing whole three phase rare earth magnet alternators (or generators as they should be called) that are putting out anywhere from 500 watts to 2000 watts! Thats a lot of juice to power up some gaming consoles!!! I on the other hand have a few PM DC Motors laying around I'm sure one of them will work. I had settled on using a 90 VDC PM Motor (1200 RPM's) that had come out of an industrial rock tumbler, apparently the speed controller on it had long sinced burned out and they just tossed it out, so I kept the motor and the pulley system that was used to drive the tumbler (Thanks to Tom Sheerin for the rock tumbler).

I started out by putting it on the lathe at the shop to see what kind of juice I can squeeze out of it at what RPM's. @ low RPM's it was putting out 18+ VDC unloaded, so I figured with the wind currents in my area, my propellers would have to be almost 8 feet in length each to get any kind of usable power out of this, that would be over a 16 foot diameter swept area! I did not have anything that big to make propellers out of, So I decided to use the belt driven pulley that was on the original tumbler unit to multiply the output of the propellers by 3 to get a 3 to 1 ratio, so if my propellers are spinning at 300 RPM's, my motor shaft would spin 3 times as much or at 900 RPM's. The shaft on the pulley was a little small (1/4" Dia.) to attach any kind of propeller hub to that would work for the job, so I turned a new shaft out of some solid stock down to 5/8" (the only bearings I had laying around had a 5/8" bore), then I rebored the pulley hub, I also fabricated a bracket on the CNC plasma cutter to attach the new pulley assembly onto the motor itself, once I got everything folded, welded and attached with some 3/8-16 hardware, this is what I got.... I ended up using a much smaller pulley on the motor shaft than originally planned, (I found this smaller one hidden in a pile of "spare parts"), so now I have about a 4 to 1 ratio.

I then proceeded to use some 2" Diameter steel tubing I had at the shop ( I Keep quite a bit of scrap pieces for times like these!!)

to make the yaw pivot for the generator, the motor had a mounting bracket attached to it already so I just made a mounting plate about the same size as the motor plate

out of some 1/8" AR plate and welded that to the 2" tube with a 2 degree tilt on the front part of it to keep the propellers from hitting the pole during high winds. I also welded on another 5/8" rod 45 degrees of center of the yaw pivot for the furling mechanism of the tail boom, the angle it is set at at is dependant on a few factors, mainly, wind force against the propellers+ weight of tail boom assembly + ability of tail to keep facing into wind direction (this is dependant on how wide the tail is, the wider it is the more surface the wind has to blow on it to keep it going the same way as the wind direction) when the force excerted onto the propellers by the wind exceeds the weight of the tail boom it will cause the generator head to fold out of the wind while the tail boom keeps itself pointed into the wind, this hopefully will prevent it from getting destroyed in storms with high winds. I Figured for the size of the props I am thinking of using, it should furl at around 30 to 32 mph winds, we will see when that time comes, nature will be the judge of that.

With all of it put together this is what it looks like, a little bit of paint later on will improve the looks of it a bit and prevent any of the steel from rusting from exposure to the elements. As you can see from the picture below, all the weight of the propeller assembly will be on the bearings supporting the pulley shaft, not the motor shaft, this will prevent any premature wear and tear on the motor shaft bearings. Also in the pic below, you can see the giant washer I welded to the yaw pivot post, once I slide the head onto the pole this will act as a pivot plate for the generator.

Pic below shows the head unit with tail boom assembly...

(Container of softair pellets come in handy for supporting your project for pictures, lol)

More details to come..... stay tuned!

Back to Windmill Generator Project


	Morse-Code \| home Starting a windmill project \| DC Motor Generator Section \| Making Propellers out of SCH40 PVC \| Making an Anemometer for the Windmill \| Charging Some Batteries \| Notes and Updates DC Motor Generator Section (June 18, 2009) After doing some extensive research, (No not at a library, on the web! Who needs libraries when the internet is full of information?? Technology improves, mankind loses its place in the world.) Anyway, I see a lot of people are using the AMETEK brand of DC PM Motors (which are now rare and very expensive on ebay!), and some brands of PM motors that come out of treadmills. A lot are rebuilding alternators, and designing whole three phase rare earth magnet alternators (or generators as they should be called) that are putting out anywhere from 500 watts to 2000 watts! Thats a lot of juice to power up some gaming consoles!!! I on the other hand have a few PM DC Motors laying around I'm sure one of them will work. I had settled on using a 90 VDC PM Motor (1200 RPM's) that had come out of an industrial rock tumbler, apparently the speed controller on it had long sinced burned out and they just tossed it out, so I kept the motor and the pulley system that was used to drive the tumbler (Thanks to Tom Sheerin for the rock tumbler). I started out by putting it on the lathe at the shop to see what kind of juice I can squeeze out of it at what RPM's. @ low RPM's it was putting out 18+ VDC unloaded, so I figured with the wind currents in my area, my propellers would have to be almost 8 feet in length each to get any kind of usable power out of this, that would be over a 16 foot diameter swept area! I did not have anything that big to make propellers out of, So I decided to use the belt driven pulley that was on the original tumbler unit to multiply the output of the propellers by 3 to get a 3 to 1 ratio, so if my propellers are spinning at 300 RPM's, my motor shaft would spin 3 times as much or at 900 RPM's. The shaft on the pulley was a little small (1/4" Dia.) to attach any kind of propeller hub to that would work for the job, so I turned a new shaft out of some solid stock down to 5/8" (the only bearings I had laying around had a 5/8" bore), then I rebored the pulley hub, I also fabricated a bracket on the CNC plasma cutter to attach the new pulley assembly onto the motor itself, once I got everything folded, welded and attached with some 3/8-16 hardware, this is what I got.... I ended up using a much smaller pulley on the motor shaft than originally planned, (I found this smaller one hidden in a pile of "spare parts"), so now I have about a 4 to 1 ratio. I then proceeded to use some 2" Diameter steel tubing I had at the shop ( I Keep quite a bit of scrap pieces for times like these!!) to make the yaw pivot for the generator, the motor had a mounting bracket attached to it already so I just made a mounting plate about the same size as the motor plate out of some 1/8" AR plate and welded that to the 2" tube with a 2 degree tilt on the front part of it to keep the propellers from hitting the pole during high winds. I also welded on another 5/8" rod 45 degrees of center of the yaw pivot for the furling mechanism of the tail boom, the angle it is set at at is dependant on a few factors, mainly, wind force against the propellers+ weight of tail boom assembly + ability of tail to keep facing into wind direction (this is dependant on how wide the tail is, the wider it is the more surface the wind has to blow on it to keep it going the same way as the wind direction) when the force excerted onto the propellers by the wind exceeds the weight of the tail boom it will cause the generator head to fold out of the wind while the tail boom keeps itself pointed into the wind, this hopefully will prevent it from getting destroyed in storms with high winds. I Figured for the size of the props I am thinking of using, it should furl at around 30 to 32 mph winds, we will see when that time comes, nature will be the judge of that. With all of it put together this is what it looks like, a little bit of paint later on will improve the looks of it a bit and prevent any of the steel from rusting from exposure to the elements. As you can see from the picture below, all the weight of the propeller assembly will be on the bearings supporting the pulley shaft, not the motor shaft, this will prevent any premature wear and tear on the motor shaft bearings. Also in the pic below, you can see the giant washer I welded to the yaw pivot post, once I slide the head onto the pole this will act as a pivot plate for the generator. Pic below shows the head unit with tail boom assembly... (Container of softair pellets come in handy for supporting your project for pictures, lol) More details to come..... stay tuned! Back to Windmill Generator Project