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Forum Index : Windmills : Blade help
| Author | Message | ||||
redbullalan Newbie  Joined: 17/01/2011 Location: United KingdomPosts: 38 |
Hi im back and still in need of your help got my first mill built and it works BUT it keeps smashing the blades. I have tried 3 different blade types (all home made ) a 6 blade a 5 blade with different lengths of blade. All have come to a sad end 1 was due to no lode i think it went to fast. I have a Kettler dc motor 1.8 hp 220v dc input 6 a 1300w 4800w 4800 rpm/ccw Model GMCD105 Anyone with some advice on size of blade shape patterns amount funds are low so has to be home grown. Please help 
Reddbull alan |
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shawn Senior Member  Joined: 30/03/2010 Location: New ZealandPosts: 210 |
have you read oztules post on making wooden blades with a chainsaw not sure on the size of your shaft but wooden blades are very hard to beat and home made out of plastic pipe would not stand up with the wind i get here. also i tilt the turbine back so to give plenty of distance from the pole. 
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| redbullalan Newbie Joined: 17/01/2011 Location: United KingdomPosts: 38 |
Thanks i will give wood a go i have had one go before never put it on as it was just out of a bit of scrap wood. thanks for your time Reddbull alan |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yeah I agree with Shawn, you cant go past timber. They are cheap and strong, and they dont have to be perfect to work well. You can buy extruded or cast blades, they work well but cost much more that a timber plank. If you have the time, timber is the way to go I did play around with PVC blades cut from pipe like yours. They work pretty good in low winds, but will bend back and hit the tower in strong winds. Let us know how you go. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| redbullalan Newbie Joined: 17/01/2011 Location: United KingdomPosts: 38 |
Hi i have see two plans on wooden blades the chainsaw one and one from utube Has anyone got some dimensions or how to plan for the blades size i need i can do a 4 blade. useing about a 600 blade then hub 600 blade is this the best size ???? What angel see one for 22 d is this the best all comments would be much appreciated Thanks for your tome so far This is a pic of the ones i put up today don’t know how long they will last Spent some time balancing them 
Reddbull alan |
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niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331 |
spending extra time balancing Alan is a good thing ...it,ll let them run smoother with less stress , i,m not so sure about a 4 blade prop , they seem to suffer (like a 2 blader) from vibration when the mill yaws and will try to shake things a bit...though saying that a 2 blade seems very close in efficiency to a 3 blade its a decent size good looking prop...maybe having a tail that furls a bit would help with the blade smashing problem ?... you could knock up a simple constant pitch 3 blade prop using hand tools and wood ,a rough airfoil shape with a bit of taper should be fine ...trick is matching the prop to the load the generator presents ...no easy answer there , experimenting a bit might be the only way ...i couldn't find any examples of the kettler threadmill motor used as a mill , if it was an ametek youd have plenty of reference material ... but theres not as much fun in that ....  niall |
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| shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210 |
To put myself on the choping block with all the number crunchers 
I would guess with those plastic blades you would not get high speed so to go wooden don't bother with anything more or less than three blades and just stabing at angles go for 3 degrees at the tip to 6 in the middle and what ever the hunk of wood will give ya at the hub. use some ply discs to sandwich them together and i balanced with lead, (not sure i should say how i did that  |
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Alan Here's a link to Alton's Calculator and you'll note that the "default" setting is 4* at the blade tip. I make my blades out of Coroflute plastic, but most folks on the forum seem to think they aren't robust enough for anything larger than the little stuff I build, which is seldom larger than 100 watts. Hope that helps you out some. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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