 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Windmills : Ax -Fx New High & Major Failure
  Page 2 of 2 |
|||||
| Author | Message | ||||
Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5123 |
You sneaked in there Oz  The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
fillm Guru  Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Well at least its not a " I Totally Disagree" Oz , but "I do have to agree with what you have said" , where the Ax Fx is working so much harder than the F&P and the extra torque is only adding to the failure point.. The F&P blade hub is similar but 3.1m dia , it is powering the Ax at the moment and will under go a complete strip down when I redesign the Ax blade hub to with stand "Force 12" .. I hope we can all learn from this and put a lot more effort into this area , I suppose when you look at the ring of bolts on the "big boys" at the blade root and they would be all 2 1/2" + at a guess , they are spelling it out for all to see what kind of forces they a dealing with... PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
||||
RevUpWind Regular Member  Joined: 03/05/2008 Location: AustraliaPosts: 60 |
Yes, for my 2 bob's worth would seem the inner shaft should take up at least a third of the blade length. At present with two dual stators, one at 1.2m blade length and SS tube the whole length with just over a quarter of bright steel stub. Have had no problems yet but the shorter length must give more strength. Other mill is 1.1m with same bright steel stubs but 25mm MS tube the whole length of blade. Am now thinking is this really strong enough and then the corrosion? Have sealed ends to try to stop moisture but think would be good idea to check and see just what is happening. I have used large pop rivets x3 in stub ends and bushes with SS grub screws with lock nuts and 3/8" cap screw in end of shaft with large washer to hold it there. Other is the same but stubs our welded onto hub. All this has worked very well, but our problem has been no lathe so hub centers from F&P's have been used which do the job but just not as well as a steel spline mount or collet setup. On a happier note with all this wind today in Hervey Bay saw the 102 make 42amps and the 80 do 30 amps. Thats 72amps and the dump fuse blew, fortunately standing there when it happened. So upped the fuse size and back in business again. You certainly have my commiserations Phil and am sure you will be back together very soon. I keep thinking how would it be if these PVC blades where extruded Aluminum as MacGyver is sort of suggesting. Extruded marine grade and anodized and lots of money. I just got to keep paying attention and learning to enjoy the moment. Peter ....River Heads - Australia The wind blows wherever it wishes; you hear the sound it makes, but you do not know where it comes from or where it is going. |
||||
| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5123 |
Thats actually a possibility in the future. There are extruded aluminium blades in the pipeline, but its some time off ( definatly not this year ), if they become available to us at all. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
||||
gpalterpower Senior Member  Joined: 19/07/2009 Location: AustraliaPosts: 175 |
Phil, Certainly is intrestering to see so many comments pouring in. Being a novice in this area,my thoughts were way track. There is more to building one than I first thought. Have to beef a few things up. ps. Got carried away with my pics I'll start a new thread in the future. Regards Marcus if it aint broke dont fix it!! |
||||
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
RevUpWind [Quote] if these PVC blades where extruded Aluminum as MacGyver is sort of suggesting Woah! Hold on here, MacGyver is not THAT clever! What I did was manufacture SHEET aluminum blades in the fashion of a modified, high-aspect-ratio Clark Y. They were hollow, pop-riveted together and fastened to a center aluminum tube using quarter-inch pop rivets and an occasional steel screw at the root, tip and one in the middle (for shear safety). The blades were VERY light and being hollow, I left the tip caps off and found the blades "pumped" air that exited at the tips and spoiled the tip vortex, which had previously created a noise problem. Any future blades made by me in this way will be symmetrical-section and have no built-in lift! If the blade gets away in a high wind, that "lift" becomes quite a force to deal with. In my case, my tower dealt with it once and for all! 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 |
||||
AMACK Senior Member Joined: 31/05/2009 Location: AustraliaPosts: 184 |
Phill, As GIZMO said someone else had a failed tube on PVC blades, it was me. It was in NO WAY the blades it was me, I used 3mm plate steel for the hub not 6mm.  I have been back to fix the stuff up and it will not happen again. I know how you feel putting all the work into it and getting home to see a big heap of now scrap steel sitting on the pole were your pride and joy once was. Since the big bang I have uses shorter blades, I went from 1.6 to 1.0 and they work well.
Andy *Note to self 1. Make it thick 2.Make it heavy. 3.Make it stronger than it should be. 4. Don't rush the first job as the second job will cost more and take mor |
||||
| fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Andy , I made mention of another failure ,that hasn't been posted yet and is similar to this where the blade tube let go at the solid to tube transition , From memory your blades smacked the tower due to flex in the very weak blade hub and a small tail causing to much yawing ,the blades were still on the tubes but pretty smashed up .. Good to here you are back in buisness , I don't feel to bad about the failure as most seem to think , the infomation and knowledge on knowing where the weak spots are far out weigh the cost and time to repair the blades.. PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
||||
JimBo911 Senior Member Joined: 26/03/2009 Location: United StatesPosts: 262 |
I have opted to use three 1/4 20 stainless bolts with washers and nylon inserted locks nuts to connect my blades to the steel innner shafts then used pop rivets to fasten the remaining blade the the tubing. Unfortunately I have been so busy with work and other personal stuff that I haven't had time to get my mill off the ground, but I did get the mast (tower)ready to go. Will keep you guys posted. Jim |
||||
| KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
Jimb911 Make sure the bolts used are a 0.003" fit or better and they MUST have a shank on them ie no threads in bearing. Stainless, stainless stainless.... not actually a particularly good material when it comes to fatigue I'm afraid. Id be going for unbrako's with an appropriate shank and washers to make sure there is no threads in bearing. In my previous feild as a quality inspector at an aircraft manufacturer, threads in bearing are a huge no-no. I have gone per the instructions on the site plus some extra for good measure however i will be drilling a ~15mm hole into the solid shaft for approx 100mm. Problem here is clearly a point load that cannot be overcome simply by chamfering the end of the tube and relocating the weld, the loads MUST spread out evenly and not end up in one place as fatigue will break it. My idea here is only a guide, no more. I have done no calculations or finite element modeling analysis. What I do know is that I have a 15mm drill bit that will reach about 100mm! and it has to be better than nothing. Karl Luck favours the well prepared |
||||
| KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
I didnt bother with the hole, the mate who did the plug welds didnt have his lathe set up and getting it anything other than straight down the guts would have done more harm than good. as mine is much smaller than phillm's rig i'm sure they'll hold up fine with 8 5mm stainless rivets per blade. Cant wait 'till my hub arrives. Karl Luck favours the well prepared |
||||
| Page 2 of 2 |
|||||
 Print this page |
 |
The Back Shed's forum code is written, and hosted, in Australia. | © JAQ Software 2025 |
