Epoxy

[Yianie123.]

I’m looking for epoxy for the stator.  Must have high temperature and strength.  Will also be used to stabilize axil shaft in tube (used as glue).  Any suggestions will be appreciated.

[MagnetJuice]

Yianie, I hope that you did not get the impression that it is OK to use stainless steel or aluminum for the rotor to mount the magnets. You can use aluminum or stainless if you want to, but you will end up with an alternator that puts out only a fraction of what magnets mounted on steel can put out.

Here is an image of a magnetic circuit.



As you can see, the plate for the magnet has to be magnetic in order to provide a path for the flux on the other side of the magnet to return and complete the circuit. If the rotor plate is not magnetic, that flux will be lost and you have a weaker magnetic field passing through the coils.

Before you spend any more money on materials, you should invest $10 on the digital download of Hugh Piggott recipe book. You can get it in metric or imperial units. You will learn a lot and end up with a nice alternator.

To cast the stator use vinyl ester mixed with talcum powder. All that is in Hugh's book.

Ed

[Yianie123.]

Thank you for your great response.  You answered the question of using alumimun vs steel nicely.  Can you recommend a brand for the epoxy to use?

[MagnetJuice]

When you asked the question about using stainless steel or aluminum on another thread, most of us missed the part about using stainless or aluminum for the magnet rotors too.

That is why I took the time to answer it on my previous post.

Vinyl ester is one of the best resins to cast the stator because it can withstand higher temperatures than polyester and it is better at resisting moisture. After mixing the resin and the catalyst, make sure you add a thickener like silica or talcum powder (baby powder) to the mix to keep the stator casting from cracking. If you use talcum powder, make sure that it is pure talcum. Some cheaper brands of baby powder use cornstarch. It would be a disaster to use cornstarch. Some people add chopped fiberglass to the resin mix to make the stator stronger.

I have bought vinyl ester from this place. Excellent stuff and a good price.

https://www.tapplastics.com/product/fiberglass/polyester_resins/tap_marine_vinyl_ester_resin/34

If you want to use silica for the thickener instead of talcum, this is good and cheap also.

http://www.totalboat.com/product/silica-thickener/

Happy building!

Ed

[Gary]

You will have hundreds or thousands of dollars, or Euros, or Pesos, or Yen in a working wind generator.  Do you want to use the experience of someone who has actually done it before?  There are a lot of dreamers on these forums who are happy to share all kinds of information that THEY THINK MIGHT BE RIGHT.  Might be the best product in the world for their Corvette or their boat but encapsulating coils exposed to the weather in wildly changing temperatures may be quite different.  I might be missing something but I have no idea what you are building.  Pictures?  Plans? Like this <link>. also makes a difference where on the planet you are.  Availability of material varies depending where you are.

[MagnetJuice]

Gary,

What do you use to encapsulate your coils?

Ed

[clockmanFRA]

I have 3off 12 footers following Hugh Piggotts design.

My coils are encapsulated with a polyester fiberglass resin with half weight is fine talcum powder. This talcum powder stops the polyester from overheating and fracturing during the hardening chemical process.

Once out of the moulds I further paint on a Vinyl ester resin as a top protection coat.

I understand that Vinyl ester resin will withstand Ultra violet UV from the sun where polyester will eventually degrade. The problem with Vinyl ester is that it is not fully water resistant but polyester is.

I also use 2 mix Expoy Araldite but the shelf life is short as the resin creeps out of the tin.

[dnix71]

MagnetJuice real talcum powder may become unavailable in the US. It's a different mineral, but frequently found together with asbestos in nature and that's why corn starch has been substituted.

https://www.fda.gov/cosmetics/cosmetic-ingredients/talc There are lawyers jumping into this from all over.
https://www.cancer.org/cancer/cancer-causes/talcum-powder-and-cancer.html

There are people who mix baking soda with cyanoacrylate (super glue) to make a rock hard epoxy-like material. Also, the micro acrylate in copy toner has been tried. Makes very lightweight build and pretty colors.

https://www.instructables.com/id/Baking-Soda-Reinforcing-Glue-Repair/
https://www.rcgroups.com/forums/showthread.php?26855-Baking-Soda-in-Epoxy

[MattM]

Wouldn't toner turn your mold into an infrared receptor?

You want to dissipate, not collect heat.

[Yianie123.]

Thank you everyone for your input.  I have come across high temperature copper wire for my stator (free).  I’m interested in finding out the max temperature for the vinyl ester that was given in the earlier string.  The distributor does not know.  Any info on this will be appreciated.  I fear burning up the stator in the hot Phoenix sun (115F in the shade, in the sun, hard to tell).  Thank you.

[MagnetJuice]

The tapplastics website has the data sheet for that particular vinyl ester resin. They list a maximum temperature of 241 F. That is typical of those resins.

I have read that if the resin is reinforced with fibers, it can withstand higher temperatures.

You don’t have to worry about the sun, it is the excessively high currents that sometimes can go through the coils that produce the heat. Keep the stator resistance as low as possible to prevent very high temperatures. The best way to do that is by using the thickest magnet wire that you can fit in the available space.

Ed