Author Topic: Blade Material (Read 5040 times)

fabricator · « **on:** September 19, 2009, 12:46:45 AM »

I'm getting close to starting my blades for the 17 footer, I have been shopping for wood, clear western red cedar will be close to 1000 bux, applenonia (or something like that) will be 400-500 bux, I can get ten foot pine 2x4s with a few small knots for $2.78 each so that would be around 100 bux for enough lumber.

I have a large pile of air dried red oak but I assume that will be too heavy for blades, I'm leaning towards the pine 2x4s, input would be greatly appreciated.

birdhouse · « **Reply #1 on:** September 18, 2009, 08:23:03 PM »

fabricator-

i dunno what part of the country you live in, but here in portland, or, home depot sells 2 X 3 8 footers for 1.63 a pop. they are all fir, and mostly clear. some even VG. if you spend some time picking through them you can get some amazingly nice lumber! (look at my recent post and i show the stock i used) i spent 30 bucks for enough wood for an 8' set (laminated). the largest downside is they are pond boards, so some controlled drying time is needed. wood framing lumber varies greatly between lowes, home depot, parr, and other yards. 2 X 3's seem to get the best stock. look around, you'd be suprised by how nice of lumber you can find, however kild dried stuff is typically not anywhere near as good of wood, but it's already "dry".

as far as i've read here, hardwoods aren't neccesarily bad. they will probably be slower to start up, but may carry that speed/momentum through a lull in wind whereas a light set may stop, then have to start up again. with the shear size of a 17 footer it may just plain make the mill "too" heavy.

if you are laminating blades, don't be afraid to let adjacent boards "f%$^&" eachother. common practice for framers. basically if you have one piece of wood with a bad warp, stick it next to another one with the opposite warp and they will cancel each other out (in theory). good luck with your decisions!

Jerry · « **Reply #2 on:** September 18, 2009, 08:38:00 PM »

Hi birdhouse.

Sorry to but in here but. I'm in Salem. I"d like to see your genny once she's up and flyin.

My Hugh Piggot 4ft is built from laminated wood and its awsome, but thats because I didn't built it.

Jerry

tecker · « **Reply #3 on:** September 19, 2009, 02:17:27 AM »

Poplar is good and easy to manage .

freejuice · « **Reply #4 on:** September 19, 2009, 03:43:01 AM »

Hi Fabricator,

I'm still new to the wind generator stuff but i will thorw my hat into the ring on this one too. I just finished up some 5 foot blades out of white pine... around here most home builders use the stuff ( South Carolina). If they have it in your region you can pick through some boards at Lowes or Home Depot you will come out very good in price. The stuff works beautifully and ends up stable & fairly light weight.

If not mistaken I think the Dan's once used it in one of their projects..its somewhere around here in their site.

Personally I would stay away from yellow pine, while its very very stong, its weight can vary greatly from board to board. some have a lot of sap in it and some of the heart woood planks can burn like a torch if you lit them. Likewise they can bend,warp and twist if the sun hits them. I have seen a small 1x2 yellow pine board about 10 foot long bend so much it all most ressembled a hockey stick when left out in the sun for a week or two.

fabricator · « **Reply #5 on:** September 19, 2009, 08:14:35 AM »

Thanks for the input guys, interesting stuff, menards is having a sale starting tomorrow on select white pine, these boards are clear and very straight with no warp, I need 8'6" boards so the 3x8 firring strips won't work.

defed · « **Reply #6 on:** September 19, 2009, 08:34:50 AM »

if i ever get around to making some blades, i may check into poplar. it has a nice grain and is easy to work with, and not too heavy.

Tritium · « **Reply #7 on:** September 19, 2009, 08:39:23 AM »

You can get complete blades here way cheaper than 1K.

http://www.royalfabrication.com/custom.htm

Thurmond

birdhouse · « **Reply #8 on:** September 19, 2009, 10:00:05 AM »

scarf joints may work to join short boards to make a long one??

when done correctly with good glue the joint is typically stronger than the wood itself.

i don't think i'd try it, but its a thought.

maybe if every other board was full length and scarfs in between?

you can save wood to by only glueing the long boards where they need to be. in other words, your blanks can have shorter boards along the trailing edge as your going to cut the down anyways.

those royal fabrication blades do look nice!

SparWeb · « **Reply #9 on:** September 19, 2009, 10:20:28 AM »

Here's how I glued together several planks of 1x8 (0.34" x 7.5") western red cedar:

Putting 5 boards together this way takes out all of the warping and if I was still concerned about it, I could clamp additional square steel tubes on the sides to hold it as the glue dried.

I love working with cedar. For 8' blades, I don't need any power tools to cut and carve easily.

Dave B · « **Reply #10 on:** September 19, 2009, 10:30:45 AM »

I have run both the Poplar and now Ash blades from Dave here at http://www.royalfabrication.com/test.htm indicating the strength of properly laminated blades. 16' and 18' and he will be running his 20' very soon.

I am completly sold on wood as the premier blade material for cost / performance and durability. I think there is a line of thought out there that blades need to be light weight. This is probably based on the fact that hand carving might be easier with softer (lighter) wood.

If you are concerned about running heavier blades then maybe you are actually concerned about the construction of your machine ? Overbuild everything with a wind system, Mother Nature will show no sympathy sooner or later.

As a testament to this 222 profile and the quality of these machine carved blades, they really kick ... There is a reason why Bergey has been running a similar profile on their machines for so long as well. Dave B.

dlenox · « **Reply #11 on:** September 19, 2009, 10:59:34 AM »

Fabricator,

I used Sassafras for my blades, it's referred to as 'poor mans hardwood', but I have a butt-load of it in my pole bard that I bought a couple of years ago for $.50/bft!

Also put on an outside layer of glass cloth which is working out real well.

Dan Lenox

fabricator · « **Reply #12 on:** September 19, 2009, 01:53:44 PM »

Thanks for that link, that is very informative.

fabricator · « **Reply #13 on:** September 19, 2009, 04:01:29 PM »

Yeah I know Dan, I've read your blade page about 50 times

I may do the glass thing, but I will for sure at least paint them with a good epoxy.

nekit · « **Reply #14 on:** September 19, 2009, 04:40:23 PM »

I've been trying to decide on what to use too. I think I'm going to go with White Pine. Mid weight, easy to find and fairly low cost. I was thinking of going with 1x 4's if I couldn't get 2 x4's without knots. I'll be interested in hearing what you decide.

Rob

fabricator · « **Reply #15 on:** September 19, 2009, 05:59:55 PM »

I went to Menards and got white pine 1x4s, they call them quality boards, I sorted through the stack and got mostly clear with some very small tight knots, I only got enough for one blade as I wanted to see how they would act when clamped up, with a little tapping they look pretty good'

Since they are 3.5" wide I plan to only plane off enough to flatten everything out and use a little more angle at the root, I'm wondering if fiberglass cloth between the laminates, say, every other one, would make the blade significantly stronger?

I'm also wondering about Titebond III glue, it says 10 minutes open time, it's gonna take me a lot longer than 10 minutes to lay these things up.

oztules · « **Reply #16 on:** September 19, 2009, 08:39:39 PM »

Dave " As a testament to this 222 profile and the quality of these machine carved blades, they really kick ... There is a reason why Bergey has been running a similar profile on their machines for so long as well."

I'm still trying to work out how Bergey manages with their blades to not require dump loads, not need to be loaded, can still furl normally no load or full load, and control charging by unloading the mill when the batteries are full.....what kind of blades are these???

They have weights 3/4 out the length, but claim that these are for easy start, not power dissipation.

Your blades don't do this I think.... whats the difference then.

??

...........oztules

birdhouse · « **Reply #17 on:** September 19, 2009, 08:59:48 PM »

tightbond III is a great glue. i use it at work all of the time, however, i was a little weary of using it on my turbine blades. i opted for gorrila glue. it's poly based rather than water based, so i'm guessing it's stronger and has more weather resistance. running your blanks through a planer after glue-up will remove excess glue and make your blanks flatter and more uniform. i just don't know if a 8.5foot blade will fit through most planers? is the root larger than 12.25 inches? i'll bet the glass would make it a stiffer. i'd rather put it on the exterior leading edge ect. that way it adds strength and protects against wind erosion at the same time. both would probably be the cat's meow!

how are you gonna carve em?

wdyasq · « **Reply #18 on:** September 19, 2009, 09:19:47 PM »

" if fiberglass cloth between the laminates, say, every other one, would make the blade significantly stronger?

I'm also wondering about Titebond III glue"

I'll go second first here - ANY good modern waterproof glue joint should be stronger than the wood IF PROPERLY PREPARED, CLAMPED AND CURED. This also means proper temperature control of the part.

I don't like the idea of glass laminates in the blades. Glass is MUCH stiffer than the wood and a glass covered wooden object really becomes a 'wood-cored glass structure'. This structure becomes very interesting (read complex) and the strength depends on a LOT of different factors including resin properties and glass properties. The place to put the 'glass' is on the outside for stiffness, in the most simple terms and the resin used must bond to the wood and trap the glass in a matrix (epoxy is the only product I know that has these two properties and not all epoxies).

Ron

imsmooth · « **Reply #19 on:** September 19, 2009, 10:06:22 PM »

Read this.

http://www.mindchallenger.com/wind/bladecarving.html

Dave B · « **Reply #20 on:** September 20, 2009, 12:37:08 AM »

Bergey has a system that works well for sure as this has been proven over time. The blade profile is similar to the 222 but like you said that's probably where it ends. At one time I knew they had weights on the ends which would flex or twist the blades I think for overspeed protection. I don't see these anymore and maybe their furling system makes up for it somehow.

Looking at their 10 K Excel unit I see their tail is bent and their offset appears much less in proportion to the blade diameter than the typical "Dans" set up. As we all know there are many, many variables that have an effect on furling and I think this is part of Bergey's magic.

I have had to make many changes from the "standard" design because of the specifics of this particular blade profile. The 222 may self limit but I'm not anxious to find out how fast that is if it does. The blades accelerate like a bat and pull like a bear once they hit flying speed.

I wish I knew more about the Bergey controls, look at the wild "air brake" arrangement that Wincharger came up with to limit the power of these blades. Cool but scarey at the same time. Dave B.

behoof · « **Reply #21 on:** September 21, 2009, 10:07:14 AM »

HI fabricator,

I've found that Poplar is a pretty easy wood to work with. Used it to build a 12' set and and 10' set of blades.

What I did was seek out the local Amish community and they came up with just what I needed in size and the price was very workable.

I'd definately use it again.

behoof

MacGyver · « **Reply #22 on:** September 28, 2009, 08:38:09 PM »

Oztules:

Off Topic

Macgyver here (from thebackshed.com 4m). I'm lost here. Point me in the right direction, please. Does this forum work like thebackshed or is it different?

Take for instance, this thread. I don't make blades from wood, therefor I'm just enjoying reading all the articles. I make my 'wings' out of solid aluminum. I know a zesty way to make very long, high aspect-ration hollow blades out of aluminum and would share that, but don't know if I should chime in here or start a new thread. Come to think of it, I don't actually "know" how to start a new thread.

See? Lost.

MacGyver

fabricator · « **Reply #23 on:** September 30, 2009, 04:44:10 PM »

MacGuyver, I started this thread so I invite you to have at it, don't worry about a hijack, I am a sheet metal fabricator by trade and would love to build blades out of aluminum, but I have always been afraid of work hardening/metal fatigue failure, please post your method.

taylorp035 · « **Reply #24 on:** October 08, 2009, 06:12:02 PM »

I will second that. I have poplar for many of my turbines and it is very light weight and relatively strong and easy to carve.

taylorp035 · « **Reply #25 on:** October 08, 2009, 06:20:13 PM »

I once made a set of blades out of maple..... soon found out that maple doesn't cut real well. I ended up using a 1 1/2" chisel for the whole thing. Then I made the even more stupid mistake by making the hub out of hickory. For all I cared, the hickory was as hard titanium.

Pine is somewhat weak, but it is real easy to machine / carve. Poplar is another favorite, but I find sometimes that it doesn't carve nicely and leaves large holes in your blades.

UpstateNY · « **Reply #26 on:** March 23, 2010, 05:06:35 PM »

I know this is a wood-related thread, but I was wondering if anyone had ever tried building with that pink rigid foam insulation board. Isoboard, I think they call it. My idea is to laminate enough of it together to make a reasonable blade blank, shape and carve to it's proper form minus an eigth of an inch or a few 16ths, then seal it up and give it a few coats of either fiberglass or carbon fiber. I'm in the process of building a Pigott 4-footer, just for fun and hopefully leading toward larger projects.

I envision a lighter blade starting more easily, being easier to manufacture, and less prone to fatigue damage. Comments always appreciated

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Author Topic: Blade Material (Read 5040 times)