fibre glassblades

[stratford4528]

Has any one had success in making fibreglass blades

[birdhouse]

sure, folks have done it.  wood seems to be an easier medium, unless molds are made for higher production numbers. 

personally, i chainsaw carved my wooden blades, then put a layer of fiberglass over the top of that.  the blanks were made from layers of clear fir. 

why do you ask?

adam

[stratford4528]

I have used a couple of Chinese turbines 200watt and 100watt and the blades didn't last very long. So I have decided to try and make replacement blades because I have friends who have the same problem. The blades I am trying to make will be a lot stronger more efficient and low noise. I have made the mould from a wooden blade I made. Also I am making my own turbine which I need blades for. Also I thrive on challenge. I am trying to make the blade in one  which is a problem So if any one can give me advice I would appreciate it.
Bob

[Royalwdg]

Wood is the best bang for buck. Especially in the cold climates like mine with 15 degress below zero in the depths of winter.  Cyclic stress will crack plastics and resin based materials.   Dave Moller

[Biofarmer]

 There are several ways to make 'glass blades, hybrid versions so to speak. The methods that are practical (and safe) for smaller turbines don't really apply for bigger machines.. What kind of rotor diameter are you building? I assume you have made a two part mold- what do you need advice on at this stage of the game? The mold is usually the most difficult part of the process...

[DustinDoyle]

You should look into how fiberglass home built airplanes are made.

Molds are not necessary, but may make things easier, especially if you plan on making more than one set of three.

I would likely use extruded polystyrene foam, possibly cut by a hotwire cutter, and S-glass to make the blades, with aero space grade epoxy. www.aircraftspruce.com or www.wicks.com has lots of suitable materials. I would buy the fiberglass from http://www.thayercraft.com I have no relation to any of those companies, I am just a happy customer.

If you decide to work with epoxy make sure you read up on how to do it correctly and safely.

[stratford4528]

I have made the two part mold with the help of my grandson who works in fibre glass but he has lost interest in helping me any more now he has his own family. I tried to bolt the two halves of the mold together so the blade would set as one but the leading edge did not come out very good which means that I would have to sand it into shape which defeats the object. So I was wondering if I should make them separately and glue them together after they have set.The mold is for a 10 ft turbine so if I get it to work I just cut the blades shorter to suit the smaller turbines I have. I have several turbines I want to eventually sell when I have blades for them. If its of any interest My tower I made with scaffolding 30ft tall with a 10ft by 4ft working platform then I have a 10ft mast which I can winch up and down which makes it easy to work on the turbine. If any one would like to see pics I can send some.
Bob

[stag]

Some yachts have been built from GRP/foam sandwich. You cut shapes from a dense foam and laminate GRP over it with extra layers at more stressed areas. It may be possible to make the blades and hub all in one unit using this method. I have never heard of this method being used for turbine blades,but boat builders have found it strong and light weight. Try a small test piece and see what you think. Some foams are melted by polyester resin. Maybe boatbuilding suppliers sell the right kind of foam. Some sanding may be required to get very smooth finish.

[letERblow]

Might check out "infusion" molding. Pack the mold with a cloth wrapped core and use  vacuum to draw in the resin. This posting
http://www.fieldlines.com/index.php/topic,146381.26.html
they have done some infusion molded blades.

[clockmanFRA]

Hi Stratford,

Yes I make the 3.6m diameter Hugh Piggot design, actually they are 3.7m dia.

If you search Hugh's site you will find a document by 'Engineers Without Borders'  where Hugh was involved in the creation of his design into fiberglass for the reason that in that particular part of the world normal timber was soon eaten by the insects.

Note, You really do need to stiffen the moulds or the blade distorts and twists.

The tricky part is joining the 2 halfs of a blade correctly and keeping things streamlined and the internal I beam joining to the root block. Filling with foam is fun as the window of the mix is about 8 seconds.

We here in Normandy are not commercial, we build stuff just for us. But if you are interested we can always make a set and you can watch/join in.
http://www.echorenovate.com

Here's a pic of my moulds, with the fiberglass matt precut using the templates ready for the resin. Other blades were given to me ready for testing, (cat takes a dim view of these interlopers). And see  http://www.navitron.org.uk/forum/index.php/topic,17156.0.html  For my build and further fiberglass blade info.

[Biofarmer]

Bob,
  By all means send some photos- it will save some time if we can see how the leading edge turned out. Was good practice followed in making the mold halves? As in were alignment pins/holes/notches/marks or whatever method used to assure accurate orientation to each other? Are the mold halves good and sturdy to resist warping during clamping and thermal cycling? Unless you take a more novel approach, like prepping the mold to accept two-part polyurethane foam so you can make foam blanks and then vacuum bag the glass & epoxy over it, you will always be stuck facing the "Leading Edge Join Job." The foam blank method is actually not a bad way to go, as it allows you to split the blank along the airfoil's high point and install a spar(s). This method also allows you to cast the spar directly into the foam blank if you wish.