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shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210
Posted: 06:27am 31 Dec 2010
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Greenthumbs the metal disc was the only thing on my mill i had to have someone else make they had a full workshop and balance was important here the grub screw has been replaced with a keyway and thread on the end for a bolt into the shaft
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 09:03am 31 Dec 2010
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Hi Greenthumbs,
You've got my attention with four F&P motors on one shaft. I've aquired 4 motors and planned to put up 2 mills. I'd save the cost of 1 tower if I could stack them all on one, but I'd have to consider the torque to drive it. Yearly average is 4.6ms, hieghest 80km with only gusts above that. Pressing the bearing assembly into 65mm box section works better for me, so I'll go with that.
Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333
Posted: 09:48am 31 Dec 2010
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Guy's there is a limit to things and you need to look at all the facts before jumping in feet first.
Firstly to tread untrodden ground is good, as long as you see it as a experiment and not as the answer to all prayers.
Number 1 is the cogging effect will be 4 times greater and considering is a huge issue with a single F&P stator than 4 times the effect is a big problem.
Secondly for the cost of stuffing with several F&P you could build a good alternator from scratch that would out preform a dogs breakfast of several F&P's.
The F&P is a great system to wet ones feet into wind energy but fall short of using the best advantage of the potential the wind has to offer.
Before you spend $$$ and time developing a generator that has drawbacks look towards what gives a bigger bang for the $$$ spent and most importantly how your design can be controlled in all wind conditions.
Pete.Sometimes it just works
shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210
Posted: 08:57pm 31 Dec 2010
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guys pete is right! four stattors on one mill has been done it was only good for around 1200 watts if i remember, and in truth it was heavy as hell I loved building a f&p mill and think they are a great lerning mill but all that build them and decide they want more power change there type completly most go with axflux they can really perform and if you go with a proven size all the hard work will be done.
i would recomend two books one is dans homebrew windpower and the other is hugh pigot he is a guru on this stuff.
I am hoping for around 3kw on my new mill and petes new mill is going to start in the lightest brese these figers f&p have never come close to and many have tryed.
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 11:31pm 31 Dec 2010
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Good to see high windspeed location data. Can you provide some windspeed distribution data? Such a precise average indicates accumulated data for a considerable time period. Do you have a spreadsheet of the data to share with the forum?
I think you may be pushing the mechanicals of a basic F&P spline over the longer term with more than 2 stators.
Probably better to look for an alternative.
Looking forward to seeing some data.
Gordon.
become more energy aware
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 05:04am 01 Jan 2011
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Hi to all,
Gordon you read into the wind info well. I used the Aust Gov Meteorological site to calculate 4.6ms yr average. I averaged the lowest daily wind speed for the yr, did the same for the hieghest, then found the median between the 2 to arrive at 4.6ms. 80kmp is the hieghest wind speed on any day of the yr not including gusts. The readings are taken at the closest light aircraft landing strip near my block, so I'm veiwing them as a sample only! Sorry I don't have a spread sheet to share.
Shawn I've also read the forum on the "beast" I think it was. 4 F&P motors on 1 head. Pete's assesment of the cogging problems are valid, thats why I floated wind speed details.
As far as $$$ value, I'll need to put up a tower because the foundation is deep sand. I'm looking to power up Mains pressure water pump, a computer,TV, lights and ceiling fans from battery bank. I'm anticipating F&P's will do the trick. If not I'll have a descent tower to put a more efficient head on, thats the plan anyway.
cheers Rastussee Rastus graduate advise generously
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 02:55pm 01 Jan 2011
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Hi Rastus,
this is hijacking the thread a bit, but covers info discussed above.
I wish the average was as simple as you have made it. You simply have the median of the average of the daily maximum windspeed and the daily minimum windspeed for the year.
The windspeed distribution is not a normal distribution, but usually a distorted negative exponential distribution. From my own weather data recording, I have only recorded a normal type distribution during a storm event that lasted 3 days, and had maximum wind speeds of over 100kph. If the data was a normal distribution then the mean and median would ne the same, but this is not the case for a negative exponential distribution.
here is a months data of some typical wind at my home. Dark Green is 10min average, and the orange line is the daily maximums of recorded data within all of the 10min averaging periods within the day. Note the significant difference in the graphs
for say between the 4th and 10th of the month, the true average would be close to 4mph, but with your method, would be about 10mph. I am not sure if the met data is a 10min average, or just a maximum record as such. Gust readings may be an instant maximum, and not any averaging.
I think met data is a guide only and seems optimistic. Actual location data will provide what is needed.
At my home, the wind drops off to close to calm around sunrise and sunset, except during storm events.
BTW the loads are similar to my RE setup. I use between 1 & 2kWh most days. My windmills do not provide enough power all year, but some days I have surplus. Other recharging options are used to maintain the battery.
Gordon.
become more energy aware
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 08:57am 02 Jan 2011
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Hi Gordon,
Very informative post.I'm greener than grass when it comes to forums,and unsure of the protocols, however I've welcomed all of the posts. The chat has been very helpful, particularlly from exsperienced wind generators! You are correct, the met readings are taken at set times. My home conditions are similar to yours with nearly calm sunrise sunsets with 6 or less dead calm mornings a year. Your stated 4mph average isn't enough to run the mill. However that's obiously not the case over all. I'm imagening to get 1kw out of 2 dual head F&P's. My plan is to put them a minnimum of 60ft high, hence the apprehension about the towers although I do have engineered plans to choose from. Not that it is a yard stick to go by, but a small township aprox. 40 miles away has a succesfull commercial wind farm providing its power.
If I need to post another thread please advise?
cheers Rastus see Rastus graduate advise generously
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 02:40pm 22 Feb 2012
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Hi to all,
Progress in my dimension moves slowly.I've encountered a few unknows to mounting the tool @ cutter grinding wheel to my circular saw.My brother machined the hub wheels needed to mount the wheel to the saw drive shaft.There was some end float that I reduced to minnimize wheel run out.In doing so I discovered the shaft rpm is 1/4 of motor speed so the efficient cutting speed of the wheel is 4,500rpm,but the drive shaft speed is only 1,000 rpm.My impression is the wheel will be crushed rather than cut effectively,so I'm about to conscede defeat to those who said it can't be done.Are there other helpfull considerations that I'm not aware of,some discussion would be appreciated.Cheers Rastussee Rastus graduate advise generously
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 08:53am 27 Feb 2012
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Rastus,
This is one where you should take it on the chin, scrape together the money and buy a shaft off of Trev, if you really need a splined shaft. The key to good milling is to hold the cutter and work rock steady, any movement at all, will bend an arbor or chip the cutter. A bin full of stuffed cutters and shafts is not going to save you money even if you don't put any value on your time. personal experience
Trev is selling the shaft a substantially less than an engineer would charge for a one-off job because he can do a batch and split the setup and tool cost over 5 or 10 shafts.
I do quite a few freebie jobs for people as a favor, but there are two things I expect to be paid for.
Milling work and thick walled high tensile steel.
cheers Yahoo I'm confused, no wait... maybe I'm not...
Rastus Guru Joined: 29/10/2010 Location: AustraliaPosts: 301
Posted: 11:30am 27 Feb 2012
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Hi Yahoo,
I'll take this one on the chin!Exstending splines using general workshop tools might be helpfull to other members apart from myself.So onto the next possibility!I propose to mount the purpose S.S. tool&cutter wheel onto a benchtop grinder.Adjust the mount of the grinder or the work jig,to control depth of cut.Using conventional cutting in small measure and multiple passes down to full depth should result in safe working conditions.Any thoughts?Cheers Rastus see Rastus graduate advise generously
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 11:51am 27 Feb 2012
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Dunno, if I am building something from scratch that needs a splined shaft and hub or sleeve, I use the standard spline sizes for 1000 rpm PTO's. I can buy that stuff for a fraction of what it costs me to build it. Like anything it took me a long time to find a supplier that was not ripping me off.
even the 20 spline 1 3/4 inch shaft is not that expensive and will handle 75 Kw no trouble at all.
If you found a router (multi speed)it would certainly handle plastics and aluminium etc.Edited by yahoo2 2012-02-28 I'm confused, no wait... maybe I'm not...
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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