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Forum Index : Windmills : New member-Hi all. Wood blade carving
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| Throgdor Newbie  Joined: 26/01/2012 Location: United StatesPosts: 22 |
Hello all. Been perusing this forum and site awhile now and figured it was time to join in. I've been interested in wind power for some time now. Made my first Lenz2 vawt about a month ago out of corrugated plastic, cypress stringers, 4" pvc for leading edge, galvanized steel ribs, bike wheel, and a cheap hardware store bearing. It spins...but no generator. Not really all that impressed with it. So I ran across some video's from muddymuddymudman on youtube on how to carve wood props. I was intrigued and thought, gee, wonder if you could use a chainsaw for the rough cutting? I eventually came across Oztules description here on how they (he?) made a jig and blades using a chainsaw and a power hand planer. Converting from metric was fun. Thanks for online converters. I've made the jigs after drawing them up on Sketchup. I did a rough guess on the blades and have it set up for 3 deg pitch on the tip, 11 degree pitch at the hub, 3 feet 6 inches of airfoil, 6 inches for hub area. The blade is pine and from 2X6 lumber. Planning on tip to be 4 inches wide with just a small taper. First blade rough cut went....rough. Chain was tight, however the chain is a crosscut and not a ripping chain, plus the chippers are a tad dull, especially for ripping. (Used an electric 14" poulan.) This week I ordered and got a Black and Decker power hand planer. The windward, flat side of the blade came out with a small glitch. Planed backside of blade to remove the rough chatter marks from the chainsaw....and now the tip of the blade is maybe 1/8" thick. Sigh. I'm not even at the part of planing yet to work in the curve on the airfoil. The airfoil at hub area is much thicker than at the tip and not sure how to use this power planer to taper it down. Although I'm still stumped a bit how the tip is so thin. Perhaps I'll post some images later to show the problems on my site. |
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Throgdor The first couple of blades tend to a learning exercise so don't get disapointed. On the tip end of your blade draw a profile of the tip, make a little template out of plastic, it gives you something to work to. All the best Bob Foolin Around |
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| Throgdor Newbie Joined: 26/01/2012 Location: United StatesPosts: 22 |
Hi there Bob. Thanks for the reply. I went ahead and attacked the first blade with the power planer and it actually has a curved shape to the airfoil where it should. High part 1/3 of the way back. Although this blade won't win any beauty contests, it's not bad for a first. Cut out a second blade with chainsaw after adjusting the tip area on one of the jigs. Going to attack that blade today. Throgdor / Mark |
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| Throgdor Newbie Joined: 26/01/2012 Location: United StatesPosts: 22 |
Been a couple months since my post above. I was in no way real happy with my first blades, in fact they all are firewood. So I have been brainstorming on how I can make good blades that come that don't vary in thickness or angle of attack without relying on the planer in freehand fashion so much. I came up with and made an aluminum base plate extension to fit on my planer. This thing works nice. The blade rough cut by chainsaw stays IN the chainsaw wood jigs for the planing step. So now I am back to making wood blades using the chainsaw, hand power planer, 18" belt sander (with 50 grit and then 80 grit belts). I'll be posting pictures on my website over this weekend and repost here to update so all can see what I have come up with. |
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| Throgdor Newbie Joined: 26/01/2012 Location: United StatesPosts: 22 |
My website is now updated with some images and descriptions of my current HAWT practice blades and images showing the adapter plate I came up with for the power planer. Go My Hawt project to see. (Scroll down the page past the VAWT.) T |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Throgdor Thats clever thinking with the electric planner. I like it. I think using a electric plan like you have is a good alternative to using a chain saw. Not as quick, but a bit safer and more of us would have a electric plan than a chainsaw. Can I add a link on Oz's chainsaw page to your page, so readers can see an alternative if they dont have a chainsaw? Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Throgdor Newbie Joined: 26/01/2012 Location: United StatesPosts: 22 |
Yes by all means you can add a link to my page.  However I did use the chainsaw for the first rough cut, then I used the planer, then belt sander. Someone may be able to improve on this idea though.
I was going to add a link on that page back to Oz's chainsaw blade tutorial anyway. I was in a rush last night to get some images and descriptions up, and forgot to put the link in. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Throgdor I've add a couple of pictures from your site, and a link, at the bottom of this page... http://www.thebackshed.com/Windmill/articles/ChainsawBlades5 .asp Let me know if thats OK. It might inspire others to give Oz's blade making methode a go, but using a electric plan instead of a chainsaw. Or even just to use the plan for finishing as you have done. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Throgdor Newbie Joined: 26/01/2012 Location: United StatesPosts: 22 |
That should do fine. Thank you Glenn. |
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| Throgdor Newbie Joined: 26/01/2012 Location: United StatesPosts: 22 |
Three acceptable blades from chainsaw carving spin up for the first time yesterday afternoon (October 5 2012). 
Read more of my entry at the bottom of my page here . Note, each blade is 48 inches in length. The tip AOA is 3 degrees, the AOA close to the hub is 11 degrees. No generator, simply free spinning in the wind. I am VERY impressed with this. It starts up as effortlessly as my vawt did with very little air moving (2-3 mph). For my first attempt at doing this, not bad, not bad at all.  |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Agreed, this looks like a fine job practicing making blades by the chainsaw method. When you get to attaching them to a generator there are two things I would have made different, important because of the load on the blades. First, I would have selected clear wood, no knots or defects at all anywhere along the entire blade. I would also select fine grained slow grown wood with perhaps 20 or more growth rings to the inch. The grain would run straight (or at a slight angle) across the raw plank thickness (quarter sawn) and never in a curve as that causes warping later. Warping would throw your carefully selected tip angle way out. Secondly I would not have placed the two hub mounting holes in line along the grain, this invites splitting under load, just like tearing along a perforated line. I'd used 3 screw holes drilled in a triangular pattern. The mounting plate would also cover the whole area of the blade ends, not just a little triangle like on your picture. Wood is a wonderful material, especially if its carefully selected for the job. I've built a wooden boat which gave me lots of practice with that 
I hope you read this as positive feedback as it is intended. Klaus |
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shawn Senior Member  Joined: 30/03/2010 Location: New ZealandPosts: 210 |
Great to see home cut blades I second Tinkers coments on the hub for extra strenth when they see some real wind you will get a surprize at how they come ALIVE so make sure they have a load,a good mast, and furling, otherwise it will all be for nothing but a learning curve.
keep up the good work. shawn |
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| Throgdor Newbie Joined: 26/01/2012 Location: United StatesPosts: 22 |
Yes I do take what you wrote as positive. With that said... This "rig" is purely experimental to see if the blades would even catch wind and spin up. They did, and did so impressively. Also not clear on the images, the blades are Sandwiched between TWO metal 3/16 inch thick each aluminum plates, so that should help hold off splitting. My next set of blades may be made out of cypress with 1/8" thick plywood gorilla glued to both sides of the hub area. The triangle pattern for the bolts is a good idea, however if I use the plywood on the hub area I should be able to stay with the 2 bolts, but I may offset one anyway. I am now repurposing a pair of riding lawnmower deck spindles to mount this rig on so I can let it run up. The initial bearings are/were old treadmill rollers. Not nearly sturdy enough. I'll have to do some researching into how to make a furling system soon! |
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