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Go Back   SailNet Community > On Board > Gear & Maintenance > Electrical Systems > Wind Generator Shakes Boat
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Thread: Wind Generator Shakes Boat Reply to Thread
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Topic Review (Newest First)
09-14-2011 12:32 PM
MacGyverRI Tire shops also use sticky lead weight tape for balancing motorcycle and aluminum car rims.
09-13-2011 02:14 PM
Undadar
Quote:
Originally Posted by apogee1mars View Post
Get some different color crayons and wax up the very tip of the blades while mounted on the hub. Chuck the hub and spin up the blades to operational RPM so the plane of the blades are parallel to the work surface (table). Take a piece of any stiff 1/2" round stock that is longer than the height of the rotating blades when one end of the stock is on the work surface. Slowly advance the stock into the rotating tips making slight contact with all rotating tips. Look at the color transfer on the stock at point of impact and see if any of the blades are OUT OF TRACK.
Excellent Tip!! Thanks for sharing that.

JdFinley.com | Sailing, software development, and life…
You can observe a lot just by watching.
09-13-2011 02:06 PM
apogee1mars
Track the Blades

It sounds like a blade track problem from here. Get some different color crayons and wax up the very tip of the blades while mounted on the hub. Chuck the hub and spin up the blades to operational RPM so the plane of the blades are parallel to the work surface (table). Take a piece of any stiff 1/2" round stock that is longer than the height of the rotating blades when one end of the stock is on the work surface. Slowly advance the stock into the rotating tips making slight contact with all rotating tips. Look at the color transfer on the stock at point of impact and see if any of the blades are OUT OF TRACK. If not and all are balanced something is bent.
09-13-2011 01:23 PM
donradclife Take the wind gen down in the cabin where there is no wind and spin it to see if all blades are perpendicular to the shaft so the tips track within 1/16", If they don't track, either the hub is cocked or the blades are not right--this needs to be fixed before you go on to the balancing.

Hold the shaft horizontal and and spin repeatedly in both directions to see if one blade always ends up down or if the direction reverses as the unit stops spinning. If your hub looks out of balance, swap blades around to see if it is the hub or the blades which are the issue. If it is the blades, trimming the heavy one with a sander is better and easier than adding tip weights. Adding weights to the hub is not going to fix the problem unless the hub is wildly out of balance.
09-03-2011 04:04 PM
imagine2frolic Smell like hell, and taste like heaven is what they say about durian. The candy is sweet like any other candy. I found the first couple just plain different. Eventually I was eating several at a time. They come in sticky portions, tiny pies, and in different flavors beside durian.

Some good old duct tape may be heavy enough to do the job. Bolts, and screws may have a tendency to become projectiles if they come loose. BEST WISHES in figuring it out successfully.

I've been working my way too the Phils for a couple of years now via S.F. Ca. Eventually I will get there. I love the diversity of weather, and geography. Not to mention a chance to sail there........i2f
09-03-2011 03:22 PM
DocBrauer I2c, Porfin, Undadar thanks for advice. I tried durian once and it's got to be the nastiest fruit in the world but will dare the candy. I'm a little leary about adding anything to the blades not only because silentwind in instructions says don't do that but also weight had been added to old hub and it worked with old blades. Now it seems easier to add small weights then to try and add lots of little weights then remove and my mind still says screws/bolts and washers from reading somewhere in past. Here is my plan unless someone says Doc that's stupid (wouldn't be first time). Find area that needs weight and drill small hole and add small bolt and different size/quantities washers close to outer circumference of hub until when both heavy side and bolt are held in level horizontal position then released there is no rotation. Spin again to see if is still heavy side and repeat. Do until blades stop randomly. What do you think? Do know of a golf course near Denerau I could look for tape if necessary.
09-03-2011 12:26 PM
Undadar There are a couple ways to balance any "propellor". I used to dynamically balance aircraft propellors to nearly perfect balance with computerized equipment. It sounds like you have pretty limited resources so let's go with the easier options.

The first is to remove the hub and blades as a unit, mount them on a spindle/shaft, set both ends of that spindle on a flat surface (so the blades are vertical and can rotate), and see which blade rotates to the bottom. You then add/subtract weight from the lightest/heaviest blade). I'm not sure this is possible with any of the wind turbines (not sure how the hub mounts to the unit).

The second is to remove each of the blades and then match all of them so they weigh exactly the same amount AND the weight is distributed evenly. That involves weighing the hub end of each blade and adjusting til they all match and also weighing the tip end and adjusting til they all match (like connecting rods on an engine).

There are some other factors (like blade tracking and even pitch) but I would start with matching the weight of all the blades.

The "type" of weight you use isn't terribly important. "Heavy" tape, lead tape, lead stick on weights, spray paint, etc... all work. Once you get it balanced note where the added weight is and how much and then afix the weight permanently. A taped on penny is great for the initial effort but won't last very long in normal operation.

JdFinley.com | Sailing, development, and life with JD
You can observe a lot just by watching.
09-03-2011 12:23 PM
PorFin Doc,

Meant to mention this earlier -- lead tape is often used to add weight to the head of golf clubs. I don't know if there are any golf courses or golf pro shops in Fiji, but if there are they might be a source for lead tape locally.
09-03-2011 12:22 PM
imagine2frolic Live in the Philippines

Go to this site, and at the top. You can find John Meile. He is a rep for the West System, and numerous other nautical products. He may be able to help you find the tape?.......i2f
09-03-2011 12:14 PM
PorFin Doc,

Here's a suggestion for a temporary fix. I've never tried it, but in principle it should work.

As I2F suggested, the lead tape is the easiest solution. You adhere strips to each blade, and then cut off small sections until the blade is perfectly balanced. The tape is thin, and doesn't significantly disturb the airflow over the blades. Lead tape is not that difficult to come by normally, but since you're in Oceania I can't imagine what a challenge it may be trying to find it.

So the expedient solution is to take your old hub, and start balancing it with the new blades installed. It will be tedious, but start with equal weight pieces of lead taped to the hub between the blades. From this point, follow the procedure recommended for the KISS generator -- except that you'll be decreasing the size of the hub-mounted weight instead of the blade-mounted tape. Since the position of the weights are closer to the center, they will be less sensitive to adjustment than tape would be further out along the arm of the fulcrum (i.e., out on the blades themselves.)

Once you've achieved balance, carefully mark EXACTLY where the weights are on the hub and then epoxy or polysulfide the weights to the hub. This should work, but for extra credit (and peace of mind) continue...

Obviously, you're trying to keep the wieghts as small as possible to minimize the risk of these puppies coming loose when the blade's spinning. While centrifugal forces will be less prevalent closer to the hub, they will exist.

After you've found balance you could then carefully remove and measure the individual weight of each piece of lead and tape to determine what your differential is at each point on the hub. You'll wind up with two numbers that are not zero -- this will be the mass of the wieghts you'll need to make and adhere to the hub.
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