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Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 01:29pm 10 Feb 2011
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Hi to all,
I'm interested to learn of any mechanisms adopted/adapted by members to completely stop F&P mills that are at risk of racing out of control. The proposed mill will not be closely attended and manually furling out of the wind before a potentially damaging storm may not be possible. Has anyone used an electricly actuated brake prompted through a control program? I hope I'm not drawing at straws!
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 01:46pm 11 Feb 2011
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Rastus, I am not convinced that a completely stopped blade is better than a slowly turning one in high winds.
Anyway, for a slowly turn shaft brake I would try this idea, seen many years ago on go carts .
They used a centrifugal clutch that allowed the cart to stop with motor idling and race off as soon as throttle was applied.
That could work in reverse as a brake, centrifugal weights with suitable springs do not contact the stationary brake drum until a certain speed is reached whence they slow the mill down.
The drum will need to be able to dissipate the friction heat. You could try metal on metal friction (possibly noisy) or - as I have seen in an old washing machine spin brake - little brake shoes just as used on car wheels but smaller.
The advantage of this is that no electrical control circuit is required. You just need to get the brake shoe spring tension right.Klaus
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 10:03am 12 Feb 2011
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Hi Klaus,
Thanks for the suggestions. From reading forum threads it seems that 600+ revs are entering dangerous ground, so a centrifical brake sounds like it would negate damaging the mill until I manage to set furling at optimum. Unfortunately I'm totally unfamiliar with the go cart clutch and the washing machine brake, could you name possible manufaturers to lead me to further research?
cheers Rastussee Rastus graduate advise generously
KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178
Posted: 10:43am 12 Feb 2011
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make it furl
easy!
start with it furling off at say 6m/s then tweak it until it gets to the sweet spot
ie no more output.
took me about 2 days and if you design your mill head right, takes about 5 mins each adjustment, including taking the mill down.
forget brakes might as well build an AXFX by the time you get it right..Luck favours the well prepared
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 02:14pm 13 Feb 2011
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Thanks KarlJ,
I'm not confident about the certainty of furl design. My impression is you win some and lose some because there are variables, all of which can't be taken into account. A number of mill failures and dangerous exsperiences in the forum have been put down to furl settings. These projects appear to have a good standard of workmanship/planning, so with "luck" it seems that "exsperience" weighs in heavilly. While not looking to make an AXFX mill, I do want additional control of the mills operation and willing to go with something that has already been tried and proven if available. I'm willing to go with your advise, but obviously need more imput!
cheers Rastus
see Rastus graduate advise generously
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 02:32pm 13 Feb 2011
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Rastus, its as simple as typing the words "centrifugal clutch" into google. Please do check your spelling and then look at the pictures how they work. There is info where to buy them if you are not up to making one yourself.Klaus
shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210
Posted: 03:17am 14 Feb 2011
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Hi just my take here, karl is right!! and if you go with his design, which I copied, you can adjust it so it furls way too early. This is good to start, then you can adjust slowly until happy.
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 02:12pm 14 Feb 2011
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Hi Tinker,
I've been found out, I'm not only computer illiterate! It will save me a lot of time with such a straight forward search with correct spelling.
Hi SHawn,
I'll have to look back through the forum and find KarlJ's plans and look more carefully at them. Thanks for the replies above, although they appear simple they help me better use my time and bring the project closer to being realized!
Interesting note a motor bike brake is being used on a geared F&P mill on the forum.
Cheers Rastussee Rastus graduate advise generously
What about mounting the turbine on a swinging bracket. Use a solenoid to relase a lock that then permits the turbine to point its blades upward out of the direction of the wind.
When the strong winds disappear then you can then lower the turbin such that the blades point into the wind and then apply the lock again.
The tail would need to be weighted such that when the lock is released the force of gravity would ensure that the turbine shifts and the blades end up pointing upwards.Thankyou.
Regards Darcy Randall, Perth Western Australia
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 12:29pm 15 Feb 2011
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Hi Darcy Randall,
Your proposal seems do-able as long as the head is close to balanced and the tail is fixed. The wind force of the swept area would be concentrated on the locking devise (pin/bar?) creating a heavey load for a solenoid to actuate making me wonder if it would be fail safe! Could you ellaborate further please? To reset the mill a horizontal flap on the top of the tail could supply enough lift to bring it back to HAWT in theory.
cheers Rastussee Rastus graduate advise generously
KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178
Posted: 12:19pm 16 Feb 2011
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The above is a tried and true mechanism as used on the SOMA windturbine
only drawback is the half a lifetime it will take to get it working correctly / smoothly and quietly in such an manner that it doesnt destroy itself.
Geez -lads no credit to me on "MY" design because its not -its PHILLM's
my mill is an off the sheld Phillm mark 2 which I now believe, after Phills mods to
the yaw bearing shaft attachment to be one of the most reliable machines out there.
The furling control is bat-sh*t simple and works - i have control down to decimal places of wind speed in m/s if i want it. -fact is you dont need that much control as after the f&P fails to put out any more grunt its hardly worth running it any harder.
My advise - although the f&p is free its let down in something very important -performance and at the end of the day 600W just isnt enough. for less money than you can build a tower you can buy a tower, mill the whole shooting match from Phillm and with a few mods, call it your own. and for all intensive purposes you'll have a well designed mill that works pretty well.
I have a yankee designed thing in the garage with furling tail and the lot.
$150 it can be yours use it the same way I did -a windmill learning tool
add to it steal from it play with it.
Luck favours the well prepared
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 03:12pm 16 Feb 2011
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Hi KarlJ,
I don't have half a lifetime to set up a mill and Soma keep design details close to home. Your endorsement of Phillm's mill appear well deserved,however the personal satisfaction of completing a project even with help can't be measured in dollars and cents. Some members just get a kick out of hearing their mills turning in the breese. I hope to join them in the future!
Thanks for the additional options!
Cheers Rastussee Rastus graduate advise generously
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 03:54pm 18 Feb 2011
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Hi KarlJ and Shawn,
If it's not a trade secret, can one or both of you detail the mill head and tail starting positions and then, the micro m/s adjustments that are progressively made until maximum potential is reached please?
cheers Rastussee Rastus graduate advise generously
shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210
Posted: 09:03am 19 Feb 2011
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Im sure karls is a little diferent to mine as mine was built with what i had around (not a full workshop) but hope this helps.
As you can see just one nut to loosen and the mill falls down to the mast side icreasing mast mill distance, straight up and no distance, so you want to start straight out the side and work up as you get brave i did it this way cos i could have gotten the tail angles all wrong but with this setup its very forgiving.
and the string holds the wires away from the spinning mill.
edit Buy the way if you get the blades right you should hardly here it turning in the wind unless its a gale!!
And unless my amp guage is calibrated wrong i bought it from ecoinervation top my mill can do is a kw very respectable.Edited by shawn 2011-02-21
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 01:03pm 20 Feb 2011
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Hi Shawn,
Your description supported by pictures are a practical help to understanding how to start with a mill set up, then safely control adjustments until the "sweet" spot is located. Thanks! 1kw is a better output than I'm exspecting, but if I come close to that I"ll be rapt! I'm planning to buy blades from Philm, balancing them accurarely and keeping runout within 1mm is emphasized in other threads. By keeping to these parameters I probably won't hear the mill running then, I'll have fun watching it instead. Thanks again,
cheers Rastussee Rastus graduate advise generously
windman1000 Regular Member Joined: 21/06/2009 Location: United StatesPosts: 91
Posted: 05:48pm 20 Feb 2011
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shawn
Your way looks easy but I would be to afraid of it coming loose and slipping down then not furling as much then it comes more loose to where it finally falls off.
I was having problems with getting my mill to furl at the right wind speed, so i decided to make the tail angle adjustable, I don't Have a good picture but here is a drawing.
KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178
Posted: 11:03pm 20 Feb 2011
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I'm not at liberty to give away someone elses design, i appreciate the need to DIY however a working platform to start with is haighly valuable.
this is why you always see great designs from Phillm, Gordon, Trev etc as they have built lots and learned what it takes.
AMACK -build it thick build it heavy is his motto and nature can dish it to the best of them.
make sure the blades dont come off.Luck favours the well prepared
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 02:35pm 21 Feb 2011
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Hi windman 1000,
Another viable option! If the head isn't adjustable, include it in the tail. While it was a passing thought to me, you've obviously made it work. Well done! I can follow diagrams/pictures to some exstent, thankyou, some of the practicle aspects aren't always obvious to me I've found. You have illustrated the need for 2 pivot points along with small adjustments by degrees. A number of mills are running similar setups to Shawns reliably, so it may depend on how big a spanner and brute force is used on the nut!
Hi KarlJ,
I understand your position and respect your reply. I'm not wanting to infring on anyones pattents/copywrights or income. PhillM, Gordon, Trev along with international enthusiasts have been instrumental in helping the majority of projects succeed. Generously sharing their hard earned Knowledge, is remarkable. In fact the cottage industry of Homegrown power wouldn't Flurish without the likes of people of their calibre. Shawns reply gave step by step guidelines without betraying exact measurements leaving room for an individual unit to be made. Of course I'm interested in using guidelines that are broadly accepted.cheers Rastus see Rastus graduate advise generously
shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210
Posted: 04:36am 22 Feb 2011
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windman your way would be great I guess there are many ways to skin a cat! I have very high wind here and the tail gets a beating so in my case i would not have to many joins there.
the bolt/nut that holds my mill head is bigger than the nut on my car toball so i can swing hard on a big spanner to tighten, was going to add a stop if it got loose so it would stop half way down giving max furling but have never needed it so i never added it.
Its great how almost all mills are different but the basics are the same with the good mills anyhow, posting photos of your mill will always open the door for critasisam and i have given my share, but its the way i learn best so i give back what i have learned from others.
Rastus good luck with the build!
ps have you read oztules post on chainsaw blades?
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 01:25pm 22 Feb 2011
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Hi Shawn,
I've glanced through the chain saw blade link but decided it is more work than I'm prepared for. I've used chain saws for over 35yrs, 8yrs professionally, but don't have the stamina for them now, apart from tidying a few fallen limbs. I have the idea that solid timber blades allow less wind strength behind the head to the tail, wear Phillm's shaft mounted blades would let more wind past with less turbulance. Hyperthecticly keeping the mill more stable and smoothing out furling overall. My ideas have been proven wrong and can be improved, so I'm open to suggestions?
P.S. If most heads where held on with a nut that size we'd never loose them! cheers Rastus see Rastus graduate advise generously
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.
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