just noticed something worrying

[bob golding]

had to get the turbine down today as it had stopped turning. took it apart and discovered that the vinyl ester has started to come away from the magnet rotor. i noticed a distinct  crack  all the way around the inside of the magnet disc. i haven't checked the outside as there is a stainless band around it. put it all back together for now with a larger gap until i get more time to deal with it properly. it looks like water has got in and  rust is lifting  it off. anyone else had this problem. if i have to redo the whole  rotor i think it will be worth while getting it galvanised. i live on the coast so rust is inevitable here.

[Rover]

Ok, I don't have an axial, but if the vinyl ester was comming off enough to brake it, I have to assume that was actualy good, you didn't destroy your windings or the magnets. I'm not sure widening the gap and sticking it back up was a good idea, if the condition isn't fixed, next time it may result something that does damage.

[fabricator]

I don't use resin on mag rotors, you already have a stainless band on the edge the magnets are pushed into, next time either pin or bolt your magnets on and paint with a couple coats of epoxy paint, if that resin has any cracks and lets water in it is game over, more rust will keep forming and keep pushing the magnets out.

[imsmooth]

I cast my magnets in marine epoxy with bits of fiberglass in the mix.  I used fiberglass tape to wrap around the perimeter to keep the block fixed.  The surfaces of the magnets are coated with the epoxy paint. I have had zero problems.

Here is the rotor.

http://www.mindchallenger.com/wind/axial3.html
http://www.mindchallenger.com/wind/axial4.html

[defed]

i think it was Chris Olsen who uses red oxide primer on his magnet discs and has said the stuff is fantastic.  i plan to try it when i get my 10' going.

[SparWeb]

Bob,
Sounds like trouble and I'd try not to put it back in the air until you've done something about it.
The split in the resin may be caused by the rust pushing it away, but it could also be thermal expansion, disk warping, or cracks that slowly grow with vibration in addition to the other forces. 

BTW: on first reading, I thought you wrote the rotor disk (not the vinyl) was cracked all the way around!

Galvanizing requires some heat - you don't want to bake the rotor so much that the epoxy bonding the magnets softens or the NEO loses its strength. 
Any sign that the rust goes under the magnets?
Depending on the state of the rest of the V-E and the rust getting underneath it, you may need to take it all off and start again. 
Take off the rust where you can, then try a primer/sealer that promises better adhesion to steel. 
Re-painting a rotor with the magnets still on sounds like a big headache.  I don't envy you.

[scoraigwind]

Here is a five year old rotor here on Scoraig.  I checked it about six months ago and found that it had corroded enough to lift at the centre a bit. You can see where it is rubbing. I did add washers and made a plan.  I returned on site a couple of seeks back and fitted rotor cast on galvanised plates.  It may not be the only or the best way but it's heavy duty, and I plan to keep on doing that.  We'll see.

Onward and upward.

[artv]

galvalum primer is indestructable but it has to be applied on very clean surface......any air pocket or dirt pocket will cause a failure...........I srayed miles of this stuff back in the 80's .......I'm not sure if you can still get it or not......I was'nt aware that these magnets were that suseptable(spelling)to the elements............the ferrites don't rust at all............artv

[fabricator]

Oh yeah, galvalum is still available we use it all the time, but it's not the be all end all it can still be scratched off.

[artv]

as long as nothing was rubbing that paint will stick.....assuming it was done right.....artv.....thin it down ..4 or 5 coats

[ChrisOlson]

i think it was Chris Olsen who uses red oxide primer on his magnet discs and has said the stuff is fantastic.  i plan to try it when i get my 10' going.

I've been using another chemical treatment product called POR-15 too.  The rotors still have to be painted after applying POR-15.

The jury is still out as to which one is better for me.  But I'm thinking for all-around ease of application and construction, using the red oxide rust inhibiting primer is still the easiest and best.

POR-15 provides a more durable coating but it's not exceedingly easy to handle and apply.
--
Chris

[bob golding]

got a price for galvanising the discs today.60 dollars for both.if i do have to take them apart again, which i am not looking forward to, that is the way i will go. i will try and bodge the gap with more V-E for now and see if i can get some bolts though the resin to try and hold it all down.

[Dave B]

  I'll comment again on this as I always do. Why cast the rotors and encase the magnets in a clump of solid plastic (glass) on a steel plate ? The magnets, plastic and rotors expand and contract at different rates and the rotors do flex as well. We see it all the time, the plastic cracks or opens up around the magnets, it traps water and rusts. It's all bad after that. Casting looks cool new but then does nothing but add expense, weight and is an accident waiting to happen.

  I know there are a few out there (myself included) that properly prep the rotor surface and magnets and then use a quality epoxy adhesive to secure these. A couple good coats of epoxy paint finishes the job. No pins, bolts, stainless rings or solid glob of plastic waiting to crack on there.

  Those new to the board may not know that the fear of the magnets flying off was a ligitimate concern back in the day when the original casting of the magnets was done with Bondo body filler. When the Bondo cracked, water got in and things rusted. Oh, the horror stories reported then and all the wonderful thoughts of what happened first was quite entertaining. There were many creative ideas for solutions to a problem that didn't exsit and we still see these today because we have been traumatized. Pin the magnets, screw the magnets, band the magnets, completely cast the magnets etc etc. I agree that these ideas can be good for piece of mind but a little background on the horror stories and why things happened the way they did should be a bit of piece of mind as well.

  Here's my story and I'm sticking to it (that was bad). Properly prepare the surfaces and use a quality ADHESIVE to secure the magnets. A couple coats of good exterior paint or epoxy paint and you are finished. An annual inspection for maybe a bit of touch up paint is easy to see and effective maintenance compared to seeing all the possible hidden cracks wicking moisture that could be rusting around and under your expensive magnets with a casting.

  Dave B. 

[jlt]

Don't just take the magnets and place them, they need to be cleaned. they come with a lot of grease on them. I clean mine with solvent and lightly sand blast them . and use a epoxy glue to hold them on. and wipe some urethane windshield sealant around the edges .never had one come loose yet. If you want to use the magnets   on something else  don't glue them. buy the mags with holes  and screw them on. the urethane can  be cut with a ceramic knife.I use a two part epoxy primer on my rotors.I think that i am going to try powder coating ,on the next rotors i do.Harbor Freight have a kit to do it.  Just put the rotors in the oven after the wife go's to work. Think they need to be heated to 400 degrees. powder coating is very tough.And costs less than galvanizing.Don't  heat the mags to 400 d or they will be ruined .   

[bob golding]

in response to daves comments. i did just fix the magnets to the rotors the  first time i built this turbine. i used an epoxy sealant called bondaseal here  in  the UK. it worked fine until the bearings  gave out and trashed the stator. this ripped off the nickel coating from the magnets. being in a coastal location it quickly started to rust the  magnets. i managed to salvage them and clean them up. i decided to make bigger rotors last year and use V-E. it has been up about a year and apart from this problem has performed fine surviving a cornish winter. 90 mph gales at least twice, 60 to 70 mph are common.  there are no signs of any water getting into the magnets so far. i have had this turbine around 5 years so far and it has required some nursing to keep it going. it is my only source of power apart from a noisy generator so i do try and keep it going.  gives you some idea why commercial ones seem expensive. it takes a lot of work to make a reliable wind turbine that will work in all weathers and conditions. if it was just a hobby i would have given up years ago.            

[tanner0441]

Hi

A point to ponder JLT if you are going to powder coat them the stoving process, I think you mentioned 400 deg. will total neo magnets.....

Brian.

[Dave B]

Bob,
  I just wondered if you completley cast the magnets this time in the Vinyl Ester and if so why if the first rotors were so successful ADHERING the magnets ? Take a close look at Hugh's photo. Every edge of every magnet is or has been open to moisture and of course the inner edge of the casting as he mentions as well. Thank you Hugh for your posting, photo and your thoughts now on what you will try based on what you have observed.  Dave B.

in response to daves comments. i did just fix the magnets to the rotors the  first time i built this turbine. i used an epoxy sealant called bondaseal here  in  the UK. it worked fine until the bearings  gave out and trashed the stator. this ripped off the nickel coating from the magnets. being in a coastal location it quickly started to rust the  magnets. i managed to salvage them and clean them up. i decided to make bigger rotors last year and use V-E. it has been up about a year and apart from this problem has performed fine surviving a cornish winter. 90 mph gales at least twice, 60 to 70 mph are common.  there are no signs of any water getting into the magnets so far. i have had this turbine around 5 years so far and it has required some nursing to keep it going. it is my only source of power apart from a noisy generator so i do try and keep it going.  gives you some idea why commercial ones seem expensive. it takes a lot of work to make a reliable wind turbine that will work in all weathers and conditions. if it was just a hobby i would have given up years ago.            

[bob golding]

dave, my rotot is not dissimilar to hughs except i have completely covered my magnets due to the aforementioned lack of any nickel coating. i dipped the magnets  in jenolite, a phosphoric acid deruster  and then dipped them in  galvafriod paint. it seems to be working so far. i have a test magnet outside in the elements which seems to be fine after a year outside. as regards the first set-up i just used the magnetic attraction to the rotor disc and the sealing qualities of the  epoxy. this worked fine for ages until the stator burned out in a storm and it  threw all the magnets off from overspeed.  :oi collected  them all  on the steel toecaps of my boots just from walking around the base of the turbine cursing about having lost them. got them all back bar one.

[tecker]

This sort of thing will be a problem in coastal areas . There are forces in movement that can't be a checked with paint or encapsulation . Open frames are just going to be a crap shoot . Start from scratch sand blast the rotor and  recast both rotor and the stator . Then design an enclosure for the machine to keep the weather out

[scoraigwind]

If you keep the weather out then you will have to derate the machine heavily because the cooling will be much less effective.

[jarrod9155]

My two cents on this , for a trade i am a body man in maine and we see some harsh weather salt sodium cloride on the roads new car even start rusti g in a year . So corrosion protection is right up my allie , incasing magnets in resin or anything is not good for alot of reasons resin that thick will not move the same as metal and vibration from the generator  spells problems . The best thing I can suggest is to sandblast the rotors and ether etch and paint or galvanize the metal and use a good epoxy not homedepot special something with a high psi test that mint for extreme pressure . And plus if there not seal in something they now can help cool the generator and stop the stator from producing smoke  . I added a seam sealer around the bottom of magnets after paint to stop any moisture from getting under the magets . Water will find away if possible. I have survived over 70 mph winds well over 400 rpms on a 18 inch rotor with out a magnet shotting off .

[bob golding]

got  a quote for powder coating and galvanising. they work out about the same. the only difference seems to be with powder coating i get the discs sandblasted as part of the process. i would have the clean up the discs myself for galvanising. anyone have an opinion which one to go for?

[jarrod9155]

powder coat

[DanB]

This is the sort of tricky stuff that only time unveils.  Lately I powder coat all the rotors before I fit magnets.  I do leave the tops uncovered because I like the xtra airgap and I I've seen the resin 'lift' over the tops of magnets before when I totally encapsulated them.  I don't know for sure...

But I have had exactly this problem a few times when using polyester.  I've never had it yet using vinyl ester but it would seem that BobG has now.  Vinyl ester seems to 'stick' to stuff better than polyester... maybe not good enough though.  I do know this... vinyl ester sticks a *lot* better to a powder coat finish than it does to bare steel.  I am hopeful, that by roughing up the powdercoat finish, before I fit magnets -that the vinyl ester will stay put.  I also always mix some chopped fiberglass in with the vinyl ester in that hope that if it does crack, it stays together longer...

All this said, I have no doubt someday we'll all be doing things completely differently, but for now in my mind this is the best process I've found ~ however I am really glad/grateful when folks like Bob share their failures.  It's good to know and good to keep in mind.

[Dave B]

Nice to have the authors of the "how to" books post their failures and design concerns as well, thanks guys. Maybe some kind of adendum or design updates listing here on the discussion board would be helpful to those who plan to build and have purchased the books. Tough (and expensive) to get these changes back in print I know.  Dave B.

[TomW]

Nice to have the authors of the "how to" books post their failures and design concerns as well, thanks guys. Maybe some kind of adendum or design updates listing here on the discussion board would be helpful to those who plan to build and have purchased the books. Tough (and expensive) to get these changes back in print I know.  Dave B.

Seems it would be  easy to pop a final line in the appendix to say:

Updates and revisions since this book was published will always be available Here

Web link here...

Then just put updates there in chronological order.

Just an idea

[scoraigwind]

Seems it would be  easy to pop a final line in the appendix to say:

Updates and revisions since this book was published will always be available Here

Web link here...

Then just put updates there in chronological order.

Just an idea

The way I print my Recipe books in batches of 200 at a time I do get the chance to update fairly frequently and I make a lot of small changes.  Any important ideas get posted in my updates page http://www.scoraigwind.com/axialplans/recipe%20update/index.htm  Also my blog http://scoraigwind.blogspot.com/ contains a lot of new ideas etc (as well as opinions and news).  It's hard to document every little idea that I might have as time goes by, and every trick I learn from others, but I do try to make most of it available on those links.

[tecker]

OK let's say the break down temp for the vinyl is 300 degrees ( after it's fully cured ) the  stator and  rotor should  never exceed 300 degrees at any time .
 Next the magnets are bonded slightly to the coating and have to be encapsulated ( I think that the vinyl needs to stop short of covering the mags as it will let go in top without filler )
 Everything ferrous will rust
  Spin and torque taxes the paint or coating 
   In winter the mass of water will expand and I think that's' all one needs to protect against the rest will dry with the heat and movement Just keep the rain and snow out .
 A cover really  needs to be tried and perfected to see these machines  still up in 10 years .
 The cover has to let air in in large enough quantities to work with the current design and air gap ( maybe open on the bottom )
  Thoughts

[ChrisOlson]

A cover really  needs to be tried and perfected to see these machines  still up in 10 years .
 The cover has to let air in in large enough quantities to work with the current design and air gap ( maybe open on the bottom )

I've been doing that for quite awhile.  Unfortunately I've never taken a close up photo of the thing and this is about the best one I have that sort of shows it.  The generator is at the rear of the nacelle on this machine and it has a plastic half-moon cover over it but the bottom is open.  The cover attaches to the stator with two e-clips.



--
Chris

[bob golding]

i have some thoughts on covering the alternator. as hugh pointed out  if you dont derate it it will overheat. difficult to say how much. cant think of a simple way to test it either. given that these machines have to work over such a wide power band i would be very careful about trying this myself. a cover over the top might help but probably not in a coastal location where you  get a lot of sea fog. this stuff rusts tools stored in a dry garage so to get it to work on a turbine you would have to totally  seal the alternator or really derate it. i will take pics of my  magnet rotor next time i take it down to change the bearings. this should be  soonish. it is working fine at the moment but i will definitely  have to  change the bearings before winter. i will try  bolting the V-E to the rotor disc before i try anything else. if it all ends in tears we will know that doesn't work. flux did recoomend fixing it the the rotor disc when i was building it. should have listened shouldn't i.  . i have to make a new stator sometime as i have rubbed coils on the current one which i expect will  give way in the next storm. i have the wire and the resin, just need to find the time to do it. until then i will keep it flying till something breaks, then take pics of the carnage so we can all learn.

[ChrisOlson]

a cover over the top might help but probably not in a coastal location where you  get a lot of sea fog. this stuff rusts tools stored in a dry garage so to get it to work on a turbine you would have to totally  seal the alternator or really derate it

What I'd do in that situation is build your parts, clean all the oil and grease off them, leave them outside and let them "season" for a week to 10 days until they're covered with rust.  Then you treat them with POR-15:

http://www.por15.com/whatispor15.asp

They will never rust again.  Guaranteed.  I've used this stuff for years on the undersides of semi trailers that run in salt and 15 years later they're still rust-free.  Just be careful to have anything that you don't want coated protected, and don't treat assemblies with moving parts because the stuff will weld pieces of steel together and you can't get your parts to move anymore.  After POR-15 cures you can beat on it with a ball peen hammer, burn it with a torch, dump battery acid on it, and you can't destroy the coating.  You can grind or saw or drill thru it however.

The only downside is that POR-15 is hard to apply.  When you pour it out of the can into a paint gun, if you get any in the groove in the top of the can it will seal the can shut - permanently - and you have to get the sawzall out and saw the top of the can off to get the rest of your expensive POR-15 out.  It reacts with moisture in the air when it cures - if you get overspray in your lungs it'll weld your lungs shut and that pair of lungs is useless - permanently.  And you only use an old worn out paint gun to spray it because no matter how you try to clean a new one that has a tight needle and spray cap, it'll weld your new paint gun together and you won't get it apart again.

I have no affiliation with the company that makes it, I do not sell the stuff - just used it on semis for many years, and more recently my wind turbines.  If you think what it says on their website is hype, you can get a 4 ounce can of POR-15 for like 20 bucks to try on something that you think cannot be protected from the elements. 
--
Chris

[bob golding]

hichris,
 just found a UK supplier of por-15 so i will give it a go. the top of the tower definitely needs doing so will do that first. i have used moisture  curing sealants before now. if you dont use all of the tin straight away the contents go hard and useless in a couple of months. does POR-15 do that? this will determine what size tin to buy. most of the tower is stainless except the top 10 foot or so. sounds like good stuff.

[DanG]

They sell POR-15 in 4-ounce cans if you just want to do rotors, tail boom etc...

POR-15 outgasses CO2 as it cures, it will pressurize its can and bulge the lid etc. if it gets a strong whiff of humidity, and foam up if it gets a drop of sweat accidentally tossed in it.

I have decanted POR-15 into canning jars that have kept (in a safe place if they broke) for over a year - I used 'canned air' electronics cleaning spray to displace the air in the jars and the air over the POR-15 as I opened the lid, even drizzled the canned air into jar as I poured. Just do not get it on the rim of the jar or can!