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Forum Index : Windmills : Another way of making blades?
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5019 |
Been thinking. I remember as a kid I made a glider from a kit. The thing had a wing span of 2 meters. The wings were made from balsa wood lengths glued together with about 20 balsa ribs. Then it was covered in tissue paper and doped. This gave a very rigid wing. I hate carving wood blades, the first one is easy, but its the other two that are hard. I found it impossible to make 3 blades the same. And its a lot of work and mess. I wonder how successfull a ribed blade would be. I have access to a laser cutter so I could cut out the ribs exactly. If I didn't have the use of a laser I could use templates and a bandsaw. Print out the rib templates from my computer, glue it to the timber and cut it out. The ribs would be cut from 9mm plywood. The spars and leading/trailing edges from timber. You can get some interresting shaped timber lengths from the hardware store. The main support would be steel, a length of 25mm square hollow section, extending about 1/4 of the way into the blade and bolted to the ribs/spars. This steel support would be bolted to the windmill hub. The blade skin could be doped cloth, heat shrink plastic, or even thin ( 2mm ) ply wood or balsa bent over the ribs. If you used a flat table to built it on, you could use wedges and a ruler to get the blade twist right. It would probally take longer to make than normal timber blades, but should be lighter and exactly to shape.
Any comments. The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| sangeff Newbie  Joined: 05/11/2005 Location: AustraliaPosts: 29 |
Good idea glenn, I made a hot wire and am going to do a similar thing but cut them from a block of foam and then fit an alluminium or plywood spar and sheet them with a thin layer of fiberglass, Im just waiting for the right size and price foam offcuts from the coolroom mob down the road, |
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| brucedownunder2 Guru  Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
Hello Guys,, I thought of getting a good Known section (either build it or get someone to send their recovered broken one), then off to the surfboard builder and get him to build a mould . My friend is one of these guys, he suggested it would be not very expensive ,especially if you could sell a few to recover costs-- I'm importing a set of "Art" blades from usa, the 3 blades plus the hub is around 250 bucks -they are fibreglass with strengthers in them -I'll tell you what they are like when they arrive.
Bruce -- tower is at 42 feet -pivots,raise and lowerable in under 1 minute with my big electric winch-solid as .
Bushboy |
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| dwyer Guru Joined: 19/09/2005 Location: AustraliaPosts: 573 |
Hello everyone l have been intesting making windmill blades out of stainless steel as l do not know much as what is my idea is cutting stainless steel sheet and put on the hyd press as size sheet 2mm thick & three blades will be 1200 mm long however is anyone has done this before or where l able get plan or drawing ?? as l have enought sheets to make fews blade and also intesting in wood design like Gizmo Regard Ian |
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| MrBungle Newbie Joined: 07/10/2005 Location: AustraliaPosts: 34 |
Heya Glenn, Good idea. If your laser-cutter doesn't want to do them, tell him he has no choice! I've built quite a few model-aircraft (still do), cutting ribs out manually, even with a template is a pain in the %$#!! While I was reading your post, I was thinking about mentioning foam-cored blades, but then noticed that Sangeff already did. If foam has grabbed your interest, I would add: vacuum bag the foamcore/fibreglass, It's a great finish, almost polished. And if yer set up for vacuum bagging, go for carbon! Or, for better impact protection, carbon/kevlar!! The problem with foamcore tho, you'd probably have to find someone involved in R/C with a CNC hot-wire machine, they can cut wing blanks with washout/in, which would allow the twist in the blade. A nice benefit of this tho, is you can ask for ANY profile that exists, these guys have literally millions to choose from on disk, like the NACA sections etc. They can even hollow out a core to any shape to fit spars etc. Simo Edit: Two N's! |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
I have considered making blades the way we used to make wings for paper aeroplanes. To demonstrate the process, take a sheet of writing paper, heavy grade if possible, say A4 size. Fold the paper over exactly down the middle. The fold is the leading edge of the 'wing' or 'blade'. Use scissors and cut out the outline of your blade. Now carefully glue the cut edges but before doing so push one edge very slightly towards the fold. If I have described it correctly you have a shape that looks like an aerofoil, I dont know how good an aerofoil but the paper aeroplanes would glide quite well. By skewing the overlap you can put a twist in the blade which you need for windmill blades but didnt do much for the paper aeroplanes. Oneday, when I dont live in town, I will make a set of windmill blades from sheet metal using this principal, oneday.
John
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| peter Newbie Joined: 15/01/2006 Location: AustraliaPosts: 25 |
to overcome the problem of keeping the blades all the same shape and same cog i built prop carving machine so all the blades have the same shape as the template blade which the router follows. all that is required is some hand sanding to get a reasonable smooth look |
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