Blade Hub Mounting Advice

[adaml]

Dear All,

After a bit of constructive criticism please (have google searched but can't be putting in the correct terminology).  Mounted my blades slightly differently this time around, i.e. from the edge of the root.  I don't know whether it is my paranoia but start up does not seem so easy like this.  I have used the same spec with these blades which are mounted to a 3/4hp ECM as I did with blades on a 1/3hp ECM which spin up very well.  My question, is the fact that I have mounted from the "edge" of the root influencing start up, would I do better to mount the hub in the middle of the root?

Blade length 26", TSR7.  All correctly balanced, blade weight 1lb ea.  Cogging of motor minimal at most.

Thank you.

P.S. know I can be a bit vague so please let me know if there is any other info reqd.

[TomW]

Adam;

Dis Claimer: I am not a turbine builder but have worked wood off and on my whole life.

My opinion on that method:

I think that mounting method will fail in short order. It will split along the line of the mounting bolts. Unless your laminations inside the root are different than they appear in the photos.

I would NOT trust that, especially if it will be near people in use.

Just my opinion, of course.

Tom

[Baling Wire]

In my opinion, your entire mounting hub is Too light-weight!  Get another hub with More material in IT and mount blades with more bolts.  This setup will Not last long, and as Tom pointed out; is a dangerous situtation.......

BW

[luv2weld]

It may be an optical illusion (delusion!) but the blade tips

do not look to be 120 degrees apart.

I'm basing that on the first picture and just continuing on the

leading edge line. The two bottom blades look to be too far apart.

Did you measure from tip to tip when mounting the blades?

I agree with the others, that is a little too flimsy.

Remember, it is easier and cheaper to over build than to

pick up the pieces and do it over again.

Ralph

[Flux]

I don't think mounting on the edge or the centre line will make any difference. I bet that if you swap the blades you will find differences in drag between the 2 motors is the factor that determines start up.

I also have no faith in the hub assembly but that is not your question.

Flux

[adaml]

Thanks guys, I will have a rethink of the hub assembly...... try to come up with something a bit more robust then, inc more bolts!

[bsafe]

I am also trying to come up with a blade mounting method for a ECM. I puchased a 1/2 inch motor arbor from "easypower" model # 81049. I have yet to carve blades. I plan on using Hugh Piggots method to connect the roots of the blades then sandwich the blades between thin metal plates (saw blades?) then attach the assembly to the arbor. I like the condenser fan hubs that Jerry has used but they have gotten very expensive. For the price the local shop is selling then I would be better off purchasing Jerry's custom hub,and blades.

[adaml]

Hi bsafe, sounds very similar to what I have been thinking, I have several thin metal disks and was considering bolting onto the front of the hub to give it some extra strength, possibly include another at the rear so I can get some extra bolts through - even just if as a temporary measure - need to fly this for a week then can come down and be more closely examined.  Did you get the ECM conversion done?

[wpowokal]

As shown, I see three possible areas of failure,

1. / they bend back and hit the tower.
   
2. / The wood splits
   
3. / the cup heads pull into the wood and the blade becomes sloppy leading back to 1 then 2.
   
   

Placing a disc on the front with additional bolts will suffice in the short term. For your next set of blades angle the base of each so they fit together and put a disc each side with bolts through.

allan down under

[bsafe]

I have yet to reattach the magnets. When I got the 1/3 ECM  two of the magnets were detached. I plan on wiping the rotor down with acetone then useing JB weld to reattach the magnets. I want to attach the motor to a lathe or drill press to collect some readings for the board as most of the ECM motor data is for 1/2 and 1hp motors. It is a 1/3hp x13 ECM motor and am trying to figue out if it might be usefull as a more efficient clothes dryer motor before I do surgery (the wireing conversion). Today I was able to do some work on my 21'mast. Bsafe

[adaml]

This is what I have done as an interim measure to try to add a bit of reinforcement, ideally think I would have like to add another disk to the back of the blades.  Plan to drive a few more screws in when on site:

[super windy]

HI mate

try and have plywood on both sides and at the front you can even make it triangle shaped like hugh piggott does on his turbines, make sure that once you then assemble it to your motor you balance the blades again, the easiest way is to hang a little weight at the same point in each blade and play with it till they are spot on, I hurried as usual and my blades weren't starting as they were supposed to then took the turbine down and spent a whole evening balancing them by using different methods, anyway here's a video of them sppinning and doing what they are meant to charging my batteries, hopefully you enjoy it:

http://www.youtube.com/watch?v=LmT3VlPzVz8

cheerio

windchaser