My No2 3.7m dia, (12 footer) gets a rebuild.

[clockmanFRA]

Early this year my No2, been up 11 years, suffered a total failure, as the so called 18mm thick marine plywood that clamps both sides of the blades just turned to cardboard.

And the blades just flew apart. These blades were a fiberglass design and about 3 times the weight of normal cedar wood blades.

The photo below shows one blade with a bit of one of the hubs of the so called Marine ply...



These blades as they flew apart then bent the main 12mm stainless steel bolts and damaged 3 of the cast resin coil Stator mounts.



So re-cast the 12 coil stator using Epoxy resin over the reduced size and repaired polyester cast.



Also did the same to the 2 magnet discs.
PMG all rebuilt and ready to go back on the main pole  so the blade assembly can be fitted.






Now to carve a new set of cedar blades.

[kitestrings]

Nice save.  Nice work clockmn.  I assume water impregnated the blades?  I think you had mentioned that was an issue causing imbalance.

The bade mounting jig is just a template, is that right, but you are using a metal plate IIRC blade clamping?  Look forward to seeing your blades.  Best.

[clockmanFRA]

Hi kitestrings,

Yes the blade mounting jig is just that, a drilling jig etc.

Going to use 12mm thick Aluminium 400mm diameter discs to hold the blades together this time.

Also as i have a nice stock of cedar timber, will start cutting the new blades tomorrow.

Now a Question for you, ...... My No 1 turbine has cedar blades and every year they get water in them and every year i need to re-paint and re-balance.  So with the new No2 cedar blades i thought i would coat them from new bare wood with a thin viscosity Epoxy resin, as the stuff i have been using is thin and stays paintable for about 1 hour.  On a test piece of wood the epoxy soaked into the surface about 5mm in depth, then set giving a waterproof coating.

Any opinions on that blade coating concept. ? 

[kitestrings]

Hmm, my experience is limited with best paint/finish.  I'm lucky to have a couple friends who both were very experienced automotive painters.  We originally used Imron primer, ''5000" I think it was, follow by top coats of single-part poly PPG Concept IIRC.  The primer was very good, very hard, but nasty stuff to work with as I remembered.

When we refinished last, I largely deferred to Albert, but he used an epoxy primer, and the same top coat.  It is a nice finish, I added 3M leading edge tape and I try keep them clean and waxed.  So far, so good.

All that said, I don't think we have the environmental, moisture issues here that you've battled there.  Hopefully the cedar is an improved substrate.  I gotta think it will be better.  We have (white) cedar rail fences here that are well over 100-yo.

[SparWeb]

I'd love to help, but I seriously don't have any experience with an environment like yours.  My climate is very dry. 
I probably get away with lots of other stupid mistakes I don't understand because of it.

But if stupid questions are all I can offer, here are a few more:

Are there moisture traps in your hub?
Are there exposed seams between laminations?
Are the bolts installed with a sealant or are there cavities in all of the holes?
Would you consider applying a sealant between the hub and the blades as they're assembled?
Is your hub plywood?

[clockmanFRA]

Hmm, my experience is limited with best paint/finish.

When we refinished last, I largely deferred to Albert, but he used an epoxy primer, and the same top coat.  It is a nice finish, I added 3M leading edge tape and I try keep them clean and waxed.  So far, so good.

Thanks Kitestrings, so it looks like the thinish viscosity Epoxy resin might be a goer then.

[clockmanFRA]

I'd love to help, but I seriously don't have any experience with an environment like yours.  My climate is very dry. 
I probably get away with lots of other stupid mistakes I don't understand because of it.

But if stupid questions are all I can offer, here are a few more:

Are there moisture traps in your hub?
Are there exposed seams between laminations?
Are the bolts installed with a sealant or are there cavities in all of the holes?
Would you consider applying a sealant between the hub and the blades as they're assembled?
Is your hub plywood?

Yes the 5 main 12mm bolts that hold the blades and the Hubs, to be now aluminium, will get plenty of sealant as the bolts pass through each cedar blade, although this is difficult with 5 stud hub with 3 blades. But might also treat the 12mm holes, actually they will be 14mm diameter as the studs never line up exactly, with the epoxy resin down the holes, ie pour it down and collect excess on the other side.?

 The original No2 turbine had those terrible plywood hubs, this re-build will have aluminium ones.

I did use lots of mastic when assembling the blades on the hubs, but i do wonder if the mastic just held the moisture inside.

My No3 turbine has deliberately designed drain holes in the end of the fiberglass blades. And since erection this No3 turbine stays roughly within balance.

I found my 3.7m long blade template yesterday amongst my turbine stuff, so away down to my new garage upstairs now to spend the morning choosing 3 blanks out of 6 pieces of lovely rough sawn cedar.
 These rough blanks are 70mm thick, 200mm wide and 2.2m long. These are all quarter sawn but have some small knots and grain changes so need some serious consideration which will be the tip or the root.

[Mary B]

Spray on epoxy paints seal well BUT they are nasty stuff for the lungs. Full face respirator with fresh air feed from outside the paint booth/area. I helped a guy n weekends who built steel stands for salt pellet tanks for bulk salt delivery. Salt dust on everything and sat in the rain and snow so concentrated salt water. It was very rare fr a stand to show rust, if one did it was usually a missed spot or most often a scratched spot when they put the plastic tank in when one of the guys at the salt delivery company slipped with a ratchet or wrench and gouged it. And didn't bring it back for a touch up before going into service.

A soak in marine varnish will seal the surface. Would need to make a bag and slide blade in, add varnish, pull a slight vacuum to force the varnish everywhere and open the wood pores.

I wonder if the bolt holes through the blade are where the water is getting in. You have some constant motion of the threads against the wood/fiberglass that will rub through a paint/varnish coating creating a bare material spot. I wonder if adding an aluminum tube for the bolts to pass through would help this. Rough up the exterior with 80 grit and epoxy it in place making sure the epoxy first coats all surfaces fully. The aluminum will compress somewhat between the clamping plates but will keep the blade from compressing enough to maybe open a hairline crack in the coating...

[Astro]

^^^^^^ That is where my mind went, actually it made a brief stop at flex seal, and then went to marine grade products.

[kitestrings]

If you pay some attention to coating the end-grain and the bolt-holes, I think it helps.  Then, I suppose they can still get nicked putting them on by the threads, but I wouldn't think there'd be movement once they are sandwiched and tightened.

[SparWeb]

I, too, would be wary of putting sleeves on the studs.  Bolt Sleeves are best used for controlling clamp-up forces, or permitting rotation.  Bushings in holes reduce damage from bolts bearing in to a soft hole.  Niether solves problems of moisture ingress.  Actually, a bolt sleeve just adds a new cavity for water to enter.
I am considering capillary action in addition to the natural channels in wood grain.
The sealant ideas being discussed are the best way to go.

[clockmanFRA]

Thanks guys, okay will paint the finished blades with Epoxy resin, the thinnish viscosity 2 pack stuff that is used in Marine building.

When i get to the 5 bolts passing through the blades, then i will have a serious re-think.  But so far the silicone sealant after epoxy coating down the holes, looks likely at prsent.

After 14 years of use in outside conditions, Polyester is waterproof but not UV stable as is polyurethane varnish. Vinlyester, is used as a gel coat, but its not waterproof but UV stable. Epoxy, is so far in my limited use, waterproof and UV stable.

BLADES.

To be 3off for a 3.7m diameter Wind turbine. TSR about 7, using Hugh Piggots wonderful designs for his 3.6m diameter.

My good friend 'Dimitri', French 'Off Grid' Log Cabin Nut,  his profession is a forester with all the machines to cut and drag out, had these red cedar collected from a nearby council who had put them aside for burning from there ornamental tree arboretum so no cost to Dimitri. He cut them up into usable logs, and i bagged a good section with minimal knots and a good straight grain.

6 years later and seasoned we cut the section up for 6off Wind Turbine blanks all quarter sawn and reasonable straight grain.

[SparWeb]

My favourite part!

[Astro]

Really I think we are over thinking it. If it has been up 11 years and this is the first time it has had to come down for repairs, I think you are winning.
I think even the big wind farms would be happy with 11 years pretty much maintenance free.
That said, if it can be improved, by all means do it.

[clockmanFRA]

Sparweb, i thought those cedar blanks just laying there!!!!! would get you going. lol.

[clockmanFRA]

Astro,  This is a wind turbine forum, and these need repairing so i post here.

However, on average they need to come down about every 18 months, for rebalancing and servicing, cables untwist, shackles tightened, re-paint the blades, check magnet discs clearance with the Stator and adjust, grease tail and main pole spigots. etc etc.

14 years ago making and putting up a Wind turbine was the best solution for renewable energy creation, especially as the 32 neos magnets were fairly cheap, and the parts about $1000.   PV was then expensive.  Today i can get the latest mono 120 cell panels at about $1200 for generating the same energy as 3off my turbines, and PV has no moving parts, well my PV Trackers do but that's another story.

But i will keep these 3 flying as long as practicable and as long as I stay fit.

  Today they say a Statement to the World.

[Mary B]

Your 3 turbines take up far less space so there is a trade off between wind and solar...

[Astro]

Astro,  This is a wind turbine forum, and these need repairing so i post here.

However, on average they need to come down about every 18 months, for rebalancing and servicing, cables untwist, shackles tightened, re-paint the blades, check magnet discs clearance with the Stator and adjust, grease tail and main pole spigots. etc etc.

14 years ago making and putting up a Wind turbine was the best solution for renewable energy creation, especially as the 32 neos magnets were fairly cheap, and the parts about $1000.   PV was then expensive.  Today i can get the latest mono 120 cell panels at about $1200 for generating the same energy as 3off my turbines, and PV has no moving parts, well my PV Trackers do but that's another story.

But i will keep these 3 flying as long as practicable and as long as I stay fit.

  Today they say a Statement to the World.

All I was saying is I know guys that work on the big ones and I think 10 plus years with just minimal servicing is excellent. You must have done a good job of building them to start with.

[SparWeb]

Sparweb, i thought those cedar blanks just laying there!!!!! would get you going. lol.

Oh yeaaaaah.
Don't leave out aaaany details.

[clockmanFRA]

Just to give all of you some idea of scale of a 3.7m wind turbine.

These blades are No 1 Turbine and made here in Normandy in April 2007, and went operational later that month.  Red cedar wood and ready for painting and then attaching to the PMG unit.



 

[clockmanFRA]

And one photo for the Girls.



WORK ON THE BLADES.


Firstly my grateful thanks to Hugh Piggott for his most wonderful calculations, for matching the blade dimensions and correct form/shape to the PMG output.  With out stall and with out over speed and cogging.  And yes so far all my blades are silent when running except for the hum from the PMG when outputting that electricity.

Nice one Hugh, and for those who don't know about him. He lives in Scotland, Off Grid, and plenty of wind, been doing and perfected his wind turbine design over 40 years now, and publishes How To Make books.   see .....  http://scoraigwind.co.uk/

[kitestrings]

Looking good clockmn! 

One of my favorite tools, and it’s handy for this, is a slick. They are common in timber framing. It is like a chisel, but much longer, with a lower angled bevel. You don’t hit it, just pare, and it affords great control. 

[taylorp035]

When you get to larger blades, it seems like it's almost necessary to cut the excess material off.  I've gone both ways using a draw knife for the main removal, but also have tried my hand at using band saw or hand saw.

Yes, and post lots of photos!

[clockmanFRA]

Carving the blades,....continued,

[clockmanFRA]

Aerofoil shape, and another blade finished.

[SparWeb]

Beautiful! 
Enjoying the show.

[clockmanFRA]

SparWeb,

Thank you for your kind comments.

Sometimes the road of the single minded Wind Turbine Blade maker is a very lonely one !

I will add all these Photos etc to my book in the Wind Turbine chapter.

Yes, I know that to most of you all this is old hat, and yawn, but there are folk out there who want to do, but find it difficult to get started, so hopefully this will help others to have a go.

Well that's the idea!

I posted all these on Facecloth as well, in appropriate sections, most love it and hopefully gives them encouragement.

  It shuts the bla, bla armchair wafflers up, that i do actually get out and do things!

Thanks again SparWeb,

[MattM]

I'm always impressed by the steel parts.  If only there was a way to integrate some porcelain into those coil sections to help protect the coils during flexing in extreme conditions.  You could close those gaps down even tighter.  If your disks flexed they'd rub that porcelain and not cause any abrasions on the epoxy or coils.  Kind of like some of those old industrial strength rotary tools that could handle extreme heat on the arbors.  Porcelain wears very, very slowly.

[Mary B]

Always enjoyable to see a craftsman at work producing something that is a work of art!

[PaulJ]

   "Yes, I know that to most of you all this is old hat, and yawn".

 It might be old hat but it's never yawn. Thanks for the pictures!

[clockmanFRA]

Making a 3.7m diameter Wind Turbine blade balancing jig.


For those of you with an enquiring mind and those of a you with a Mechanical Engineering bent.


So these aluminium 400mm discs will sandwich the 3 wood blades and be stainless steel screwed to each side of the blades, then the 5off 12mm bolts will pass through the whole blade/hub assembly.


The materials for the balancing jig are all below with some steel parts needing machining and cutting to size. I do love a good search in my steel stock bits, and sort out a design with what i have. Keeps the little grey cells going.

The plywood triangle is my 5 bolt hole wood jig for drilling the 5 holes in the correct place.

[SparWeb]

Aluminum 5083 is weldable, so can we look forward to seeing some shiny molten beads?!

[clockmanFRA]

Sparweb, no need for any welding.

I do have some soft.orn for you, the cedar wood blades get Epoxy coated, lovely shine.!!!!!