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turnymf Regular Member Joined: 04/10/2008 Location: AustraliaPosts: 84
Posted: 09:33am 27 Feb 2010
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(the cardboard i just ripped off a box)
Would that be a beer box Downwind?
I am with you on the "build a mini mill and learn " approach.
Will she drive a Led?
Playstation 1 spindle motors have a ball bearing disc grabber that could be used here
Might have to make one myself, feel like I'm missing out on the fun
cheers
KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178
Posted: 09:55am 27 Feb 2010
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Pete
this is it, the turbine the neighbors wont complain about!
NOW -you could make say 3-400 more of them and mount them in a frame about 10m off the ground!!!
Would the blades from a PC fan be any good?, you got a few of them around too
Nice one overall Luck favours the well prepared
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 10:34am 27 Feb 2010
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turnymf
It would be good to have your involvement.
I dont think a led is a part of it, and funny you should mention a led as i just hooked a led to the test mill and it needs a cyclone to generate 2 volts to light the led, but it will do it .....Just.
I think on the day of test the generator is provided by the olympiad and Gaby needs to supply the blades for testing.
Karl,
Yes this one wont cause a neighbor problem, but the problem is what do i do with all the power... a full 1 volt.
You should know that a PC fan is small in dia and we need torque to get this thing to spin.
Then "high" speed to get the voltage.(we are not concerned with current just voltage)
Same problem as a big turbine but smaller scale.
In actual fact its harder as we dont have the mass area.
It is what i mean by there is a lot to lean from a mini mill.
Pete.Edited by Downwind 2010-02-28Sometimes it just works
neil0mac Senior Member Joined: 26/12/2009 Location: AustraliaPosts: 210
Posted: 10:41am 27 Feb 2010
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Hmm. Here's me thinking (guessing?) that a piece of plastic with a steep(er) pitch right neaqr the centre hole would assist with the starting torque problem. Probably the height of it could be detriniental to the final RPM, though. Perhaps there is a happy middle solution?
A further thought about attaching the blades. in stead of used a 'bolt' drill holes on the blade(s) and CD and use Araldite (epoxy resin) like a 'rivet'?
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 10:56am 27 Feb 2010
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neil0mac
Im all ears on your thoughts.
1. i dont know what you mean exactly.
2. remember a 14 year old student on the other side of the world needs to be able to build this with limited resources.
I found 4 dobs of hot glue was more than enough to hold it all together in even high winds.
All up this will need to run for no more than 15 minutes on the day compared to a life time in the wind.
Good to see you are happy to lend some thought to help the young lady out.
Pete.Sometimes it just works
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 01:07pm 27 Feb 2010
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Hi Karl,
As silly as it sounded to use a pc fan blade i thought i would try one as you rightfully reminded me there was a few on the bench (along with every thing else on the bench)
I must say i doubted the thought but was proven wrong.(bitter taste in mouth now)
I tried a 75mm pc fan mounted in reverse and to my amazement it started up and spun up to 0.5 volts output.
With the 250mm double blade i got 0.7-1.0 volts at the same distance.
Still amazed it worked as well as it did.
Pete.Sometimes it just works
gabymuino Newbie Joined: 25/02/2010 Location: United StatesPosts: 26
Posted: 03:26pm 27 Feb 2010
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Good morning guys…
You’re put me crazy with all these concepts and terminology. But, “THANKS” I’m learning a lot!!!
I’m just waiting for my mom to take me to the store to buy the PVC pipe.
Meanwhile, I made a try with a plastic water bottle. The result was great I got in the high speed almost 0.7 Volts!!! that is more than on the Nationals last year score. But I still having trouble on the low speed, I don’t know what is going on, probably is my fan that is to old or the generator has to much movement.
I have couple of questions… probably you already told me. Which size is your blade? The one that I made is 20cm… Probably that is one of the reason that doesn’t work in low speed and the other is the material. Do I use the maximum size permitted that is 24cm?
What do you think?
Please comment my pictures. Gaby Muino
turnymf Regular Member Joined: 04/10/2008 Location: AustraliaPosts: 84
Posted: 03:45pm 27 Feb 2010
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Ok
Had a old ps1( busted) and fitted the cd grabber thingy to a sled motor off a old cdrom
Found a scrap of laserlite, only had trimdeck profile
Cut it out with scissors and hot glued
I made 3 sets, each looking better and more balanced as I went
They all lite the led when put in front of a big fan They performed( according to led brightness) in this pix worse futher from the motor, which the order they were made
Probably a error on my part
Easy to see why the comp has a max diameter of 24cm with no metal
Good luck with it Gaby
Just make lots of models until you find resonance
cheers
turnymf Regular Member Joined: 04/10/2008 Location: AustraliaPosts: 84
Posted: 03:59pm 27 Feb 2010
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Hi Gaby
Big is best, go the whole 24cm
I used only hot glue
A ping pong ball would make a nice nose
You're on to it
cheers
gabymuino Newbie Joined: 25/02/2010 Location: United StatesPosts: 26
Posted: 04:03pm 27 Feb 2010
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Great more help!!!
Thank you Did you test your samples?
Did you have the speed you got with each one?
Wich fan you use?
I think I need to buy a new fan My mom is going to kill me when I tell her that I need a new one
RegardsGaby Muino
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 04:49pm 27 Feb 2010
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Gaby see what you have done ? you even have turnymf
having a play now.
You have started something girl.
It is pleasing to see you are making an effort and getting some results.
Many that ask questions here just expect every one else to do the work and give them the answers.
It is nice to help someone that is prepared to help themself.
With the blades i made i used the full template size (250mm)
I figure you can always shorten a blade but hard to make it longer.
By full size (25cm) it should give greater power on startup and easier to see if a reduction is noticed by shortening the blades a small (5mm) bit at a time.
My aim would be around 23cm in the end to ensure you were well inside the maximum limit (24cm)and not be disqualified by some strange measurement. (play safe)
If you dont understand the terms we use than ask, as its not strange terms but windmill talk.
Basically you are building a windmill albeit a tiny one.
The same rules and laws apply to your mill as a bigger one. So some of the terms are important to understand.
I keep using cm and mm i hope you understand these measurements if you have trouble than say as i can work in inches but have trouble with the fractions...Wierd system!!
Pete.
Sometimes it just works
gabymuino Newbie Joined: 25/02/2010 Location: United StatesPosts: 26
Posted: 04:58pm 27 Feb 2010
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Pete,
I sent to you a couple of emails...don't worry about the measurements I can manage both Metric and English systems...I'm in a Greek school and I have 4 hours of math every day in English and in Greek both systems.
Gaby Muino
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 04:59pm 27 Feb 2010
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Hi turnymf
Good to see you having some fun too.
I think your motor is much bigger than mine and would expect a higher voltage output.
The mass of cd you have would effect the preformance greatly i would expect.
The trick here is to get enough torque to start the mill and then high enough speed to get the upper voltage range, as speed is volts here and that equals winning or loosing
Pete.Sometimes it just works
neil0mac Senior Member Joined: 26/12/2009 Location: AustraliaPosts: 210
Posted: 09:14pm 27 Feb 2010
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Edited by neil0mac 2010-03-01
gabymuino Newbie Joined: 25/02/2010 Location: United StatesPosts: 26
Posted: 09:23pm 27 Feb 2010
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Hi neil0mac,
I didn't get what are you trying to say... Maybe I'm so tired
By the way I'm a girl Could you please explain more to me?
Thank youGaby Muino
neil0mac Senior Member Joined: 26/12/2009 Location: AustraliaPosts: 210
Posted: 09:46pm 27 Feb 2010
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Ok. Now you have a pic!
I'll test you with this one!
I did consider suggesting that you could use two of those additions in each half of the blade - with a suitable hole (between them) through the blade and the CD. Could possibly give more torque without increasing the resistance at higher revs, meaning you could reduce the height of the add-ons a bit. (It is a reduced version of a PC fan.)
Certainly your wider (green) blade could probably be done this way.
(If I can mystify 'Downwind', I can mystify anyone?Edited by neil0mac 2010-03-01
neil0mac Senior Member Joined: 26/12/2009 Location: AustraliaPosts: 210
Posted: 10:10pm 27 Feb 2010
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Here is the idea improved a bit.
Instead of the wide flat section (uselss bulk that creates 'inertia' (the resistance to being moved) in the centre of your blade, use the same amount of plastic to give the 'aerofoil effect' and strengthen the blade at the same time = lighter, stronger, better.
How far you extend these from the centre will be a matter of trial and error. Also, the shape of the leading edge can be altered in any way you fancy. Probably a straight taper as per my inital diagram can be improved greatly!
Ok, so I attached them to the leading edge - not the trailing edge! Swap them around and make them the full width of the hub area.
(Aren't 'we Aussies' good at wasting other people's time (constructively, we hope!).)Edited by neil0mac 2010-03-01
gabymuino Newbie Joined: 25/02/2010 Location: United StatesPosts: 26
Posted: 10:38pm 27 Feb 2010
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You're not wasting my time!!!!
"Aussie" people are the most incredible people I never met for help I never thought before that I could have help from far away...Can you imagine...from Australia!!!!.
I still don’t get it. Are you saying that my first try can improve the starting of the blade.
Now the green one is pretty good but I’m having trouble with the low speed. The score is going to be based on the sum of the low speed and the high speed.
Gaby Muino
neil0mac Senior Member Joined: 26/12/2009 Location: AustraliaPosts: 210
Posted: 11:45pm 27 Feb 2010
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What I am getting at, is increasing the torque (turning power) by using a greater pitch near the hub - the last suggestion was utilising the green one, but with an additional hole through each blade to allow:
a) increased air flow (less flat area to cause resistance which means that less (none?) of the energy from the fan is wasted in pushing air sideways (at right angles to the motor axle, if you like) without moving anything.
b) make the blades more rigid so that they can be effectively 'narrower' at the same time.
Is that any clearer?
______________________________________
OK. I'm throwing up ideas 'outside of the normal'. Maybe one (or a combination of them) might just make a significant difference.Edited by neil0mac 2010-03-01
gabymuino Newbie Joined: 25/02/2010 Location: United StatesPosts: 26
Posted: 11:51pm 27 Feb 2010
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okidoki,
Now I got it! Gaby Muino
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The Back Shed's forum code is written, and hosted, in Australia.
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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but the problem is what do i do with all the power... a full 1 volt. 
and would expect a higher voltage output.
