Another quick one on the vinyl esther

[powerbuoy]

I was pro vinyl esther before in my post until today ... just tapped slightly on a rotor with vinyl esther embedded magnets ... (with a hammer) ... as a result the hard mass shattered and the magnets took off ... sighhhh.

Powerbuoy

[DanG]

Good point - resins alone are brittle - anything from powered flax to glass fibers or even sandblasting glass beads (no sharp edges & high mass) will reduce chances of shattering. Now just find the VE killer solvent to soak your stator in for a few days and have magnets pull themselves out of the wreckage...

[dastardlydan]

  I am sorry you had bad luck.

vinyl esther is one of the best resins to come down the pike

for a long time.

But it's a very tech type resin, there is 4 kinds of

catalis for it  like hot days , cold days. ,thick coatings,

and thin coatings,

 You can add Colloidal Silica and make very hard to sand

and tuff

  ,you can add talc to make it sandable.

Vinly Esther had to be mix to the letter to get it right

not like Polyesther,

Fiberglass power if you can find it.would be the best

for rotors.

There are all kinds of addtives you can mix with it

like west marines 404# high density filler, or

407# LOW DENSITY( dam cap lock) and 410 microlight filler.

Don't give up because viny esther it water proof

there is a posting last week rusty magnets, that

is from polyesther its not water proof.

I like fiberglass power , and talc.

So try it agin it is good stuff.

________________

[Flux]

Yes I think that you need filler of some sort. Even epoxy although it is a good adhesive will be very brittle with no filler.

I am not sure that vinyl ester is that good to stick magnets on with. As long as you have filler to strengthen the mass of resin it should be good enough.

Except for decorative things the resin alone is not a good idea, its normal purpose is to bind the fibres or particles of the system it is used with, it has little inherent strength.

When used for stators again I would add something if only talc, the windings will add considerable strength but the "ears" where the fixings are will be very brittle.

For magnet rotors I would only regard any of these resins as weatherproofing. If you use them for strength then you need a filler. The correct epoxy alone should hold magnets on, but if you cast lumps of unfilled material round them the shrinkage forces may reduce the effectiveness of the bond.

flux

[wdyasq]

I don't think anyone here recommended vinylester as a magnet potting resin. Epoxy is a better adhesive by a quantam leap  or two.

No resin should be used without reinforcement. The strength of a part is in the amount of glass fiber and the geometery.The most practical one for wind turbine use is glass fiber. In boats they use glass cloth set in epoxy to assure there is a good covering of epoxy over the wood. Certain epoxy resins are better than others for water resistance.

Searching for cheap products when you are building something you may be depending on for survival may not be the best idea. The initial cost of the proper materials is not that great if thought of over the life of a wind turbine.

Ron

[powerbuoy]

Alright, ... the filler will be the key to success. I'll built another one ....

again.

:-) Powerbuoy

[wdyasq]

The proper SYSTEM will be the key to success. If you continue to use a resin that will not BOND properly you may still have magnet adhesion problems - and later, IMO, other problems. Vinyl ester resin is not an adhesive. Not all fillers are compatible with all resins. Not all glass fibers are suited for all resins. There are reasons for data sheets and research ... and maps ... and asking directions.

I wonder how much time and money is spent redeauxing things rather than spending the time and money to do it right one time? I know I've followed that false economy.

Ron

[DanB]

Hi RonB -

I know on this board (and myself included) many of us our guilty of 'learning the hard way' - but sometimes that's valuable and sometimes we actually do figure out stuff that works and get some real experience about what doesn't and why.

That said...  I've always been curious about 'bondo'.  Isn't bondo just talc and polyester - or is it something else?  Why does it stick so well (actually - it doesnt stick that well but it's used for the application and it's impressive how well it does work sometimes) to metal on cars?

[Countryboy]

From wikipedia

Bondo is based on unsaturated polyester resin, minerals and glass microspheres. The normal formulation of a lightweight bondo body filler is the following:

    * unsaturated polyester resin ( flexible putty resin)= 50 parts by weight

    * titanium dioxide (pigment)= two parts by weight

    * talc powder 200 mesh = 44 parts by weight

    * Fumed silica (Aerosil 200)= one part by weight

    * glass microspheres(scotchlite k 15)= three parts by weight

The filler is cured using two parts of dibenzoyl peroxide paste.

[wdyasq]

Dan,

I believe it is a strictly mechanical bond. The rougher the surface is the better the crud holds and it is advised not to patch drilled holes but let the bondo flow through and anchor.

One of the true pleasures in life is spreading 5 gallons of bondo from a "hawk" with a wide 'knife', your helper keeping the hawk charged. Then one gets to go back and shave the partly cured high spots under demands the curing polyester places on you. After that there are the hours of making the surface as smooth and fair as humanly possible with long boards and sandpaper while eating the dust ..... ah, the pleasures of life.

Ron

[brian2034]

vinylester is one of the better resins used today in my opinion better than epoxy,that's from my 10 years building planes with the stuff. The only advice I can give is that any resin has no strength properties it is only used to hold the fiberglass mat or cloth.

 With any system you use epoxy, vinylester, polyester remember the resin is the glue the fiberglass cloth is the main ingredient for strength. For example gel coat on a boat is colored resin it chips easily and the thicker you make the gel coat the eaiser it will chip. If you look at the inside bottom of a boat where there is fiberglass cloth used and there is no gel coat you can hit it with a hammer and it will not chip.

 When laying up a rotor or any part you should used a quality resin and add chopped fiberglass to the mix (mill fiber) add as much as possible but don't make the resin to thick, or it won't flow around the magnets or the coil properly, this will prevent it from chipping or cracking.

Mill fibre is fine chopped fiberglass strands "buy it don't try to make it"