Has anyone ever tried this.........

[ElSuperFantasma]

My spinnig thing is kind of out of balance.

I have tried the methods that I have read over the past few months and for some reason have not been able to get it close to perfect.

So I thought about trying the following:

The heaviest blade will always have the tendency of falling to the bottom of the rotor right?  So I thought about getting a real sensitive scale and measure the weight with it while having the tip of that one particular blade resting on the scale, and then proceed with the other blades adding weight to match the heaviest one.  Of course the blades will have to be attached to the alternator while doing the aforementioned process.   It might be a crazy thing to do but heck I think I will give it a shot and see what happens. 

Blessings to ALL.

TSG

[MagnetJuice]

Go for it Fantasma. Everybody should be allowed to try at least one crazy thing once a week.

If that works for you, let me know.

I'm thinking about clasping both hands around my crotch and picking myself up to see how much I weight.
I should be able to do it because I know that I can easily lift over 180 Lbs.

[Adriaan Kragten]

I assume that you talk about a 3-bladed rotor. This procedure won't work if you use a normal balance which can measure only a positive force because for at least one of the blades, the force to keep it on place will be negative. The problem with a 3-bladed rotor is that generally one blade is the heaviest, one blade is the lightest and one blade is in between the other two. So to balance the rotor you must always add weights to two of the three blades. The only exception is when the neutral position is such that one blade is exactly vertical and pointing upwards. In this case only a weight has to be added to this blade.

You can use this effect during balancing by adding weights to one blade until another blade is just vertical and pointing upwards. From this position you know that you have to add only balancing weights to this blade.

A problem of using the generator is that it will have a certain sticking torque, especially if you use a generator with iron in the coils. But even a generator without iron in the coils will have a certain friction torque because of the friction of the bearings and the seal on the rotor shaft. It is better to make a separate shaft with two very small non sealed ball bearings. The balancing weights have the largest effect if they are mounted at the largest possible radius which is the blade tip. However this requires drilling of holes in the blade and gluing of the weight in the holes. If the blades are mounted against a spoke assembly, the balancing weight can be placed at the connecting bolts but at this position they can be rather heavy.

[WindyOne]

My spinnig thing is kind of out of balance.

I have tried the methods that I have read over the past few months and for some reason have not been able to get it close to perfect.

So I thought about trying the following:

The heaviest blade will always have the tendency of falling to the bottom of the rotor right?  So I thought about getting a real sensitive scale and measure the weight with it while having the tip of that one particular blade resting on the scale, and then proceed with the other blades adding weight to match the heaviest one.  Of course the blades will have to be attached to the alternator while doing the aforementioned process.   It might be a crazy thing to do but heck I think I will give it a shot and see what happens. 

Blessings to ALL.

TSG

What method did you try ... try that did not work ?

[ElSuperFantasma]

Good morning fellows,

I have tried pretty much everything that I can think of.  From suspending the rotor with a string from its center to even using one of those motorcycle wheel balancer.  I have also used the method Adrian mentions above, which I found it to be the most effective in my case but like he describes in his reply, the friction in the bearings does not allow to have a close to perfect rotor balance.   The best solution would be to find some friction-less bearings in order to eliminate the drag in the bearings and achieve a well balanced rotor that way.

In reality the rotor balance of the thing I built is almost perfect   

Is it Friday yet?   

TSG

[clockmanFRA]

Hugh Piggotts book,   

scoraigwind.co.uk/all-of-the-books-by-hugh-how-to-get-them/

His balancing techniques are excellent and he is a practical builder with over 40 odd years of experience.

I use his balancing methods on both my Cedar wood blades and on my Fiberglass blades.

My turbines have been up over 10 years now, but every year each needs lowering, rebalancing and servicing/painting etc so I allow 6 days.
Its the moisture that gets them out of balance.

It has to be a non wind day, shorting out of the turbine disconnected and see where the blade comes to a stop.
I use Masking tape and tape on a small piece of lead sheet onto the opposing blade at its root.  Keep adding and taking away until the blade is neutral.

For fine tuning I have a a small length of lead at about 10mm1/2inch wide and 35mm/1/1/2 inches long. I place this so it goes over in a U shape at the tip of each blade leading edge when its in a horizontal position, I start each blade with my length of lead, then slide it inwards towards the hub each time and then see which blade turns and which one doesn't and attach or take away lead at the roots.

Once happy and the turbine is balanced I attach the lead with stainless steel screws. Paint, grease, unwind the 3 phase cables, check the mast cable turnbuckles etc etc.  Yep 2 days each year. 

As I say its all in Hugh's book.




The above image shows one of my blades with a lump of lead, not yet painted, attched at the root of a blade.





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[ElSuperFantasma]

Hello there sir,

Thank you for your input on this.  I will certainly give it a try using your method and see what I come up with.

Nice looking machine you have there 

Have a blessed day!

TSG

[SparWeb]

I get static balance for my blades by hanging them with a string from the ceiling.  The string is attached to the hub, and the whole set of blades is assembled but not attached to the generator.  I suspend the blades horizontally.  You can make piles of the weights on the blade tips until they stay horizontal on their own.  Once in balanced, you know how much weight to put in each tip.  If you want, you can put weights in other locations, not just the tips, with this method.  The air in the room should be still.  This process is very sensitive.

[ElSuperFantasma]

Good day,

I have tried the static balancing act in the past with not much success, the thing about it is that the string has to be perfectly centered while hanging through the hub.   I did not have anything on hand to get things perfectly centered and the outcome turned out not very effective for me.   

If I had a lathe I could machine a plug for the hub with a perfectly centered tiny hole to run some fishing wire through it, then maybe things would work better.

TSG

[bigrockcandymountain]

I use a plug of wood cut with a hole saw in the middle of the hub.  It has a nice small hole in the center. 

A lathe cut metal plug would be even better though.