Author Topic: Piggott Blades simplification possible? (Read 95262 times)

Menelaos · « **Reply #66 on:** May 29, 2012, 10:46:32 AM »

like this?

http://www.youtube.com/watch?v=g8hioldi6TY

or this?

http://www.youtube.com/watch?v=LmtMQeoKCu8

I was about to build one like I posted in the second link but then it seemed a little bit too much work and expenses for my needs...

Max

Frank S · « **Reply #67 on:** May 29, 2012, 11:55:59 AM »

Actually that second video would be a much simpler design than the concept I was thinking of. It would be pretty simple to build and could be mounted either on a table saw or a radial arm the tricky part would be with a fixed blade of a radial or table unit the rig would have to actually move up and down while the tracing arm remained solidly fixed in relation to the saw blade.
The pattern and the blank would rotate together by a chain & sprocket their axis would be mounted in the moving end of a double parallelogram arm set up which in turn would slide along on 2 linear bearing shafts.
I might spend a little time and draw that up in my solidworks cad program to work on either machine

Menelaos · « **Reply #68 on:** May 29, 2012, 03:26:20 PM »

I did actually draw that ins Solid works 2007 as well...I will check out if I still find the file, so you can build up on that and don't have to start all over again... ;-)

For quite a wile I was really into that Idea but I am limited in space so I tried to make a construction that is very light and that can be easily disassembled. The machine has to be really stiff and accurate. Propellers are different from wind turbine blades. The sharp trailing edge is not so simple to cut accurately....if you want to get it working properly it will be quite an expensive machine. Sanding is needed anyway. I feel this is only good for a rough cut out...and it takes ages to properly set up the blank and the copy and to adjust it.

I have made quite a few blades now and I have practice with my hand- and Power tools and can get the work done quickly with those...
If I was to get some kind of automatation into the process, I would probably build something really simple similar to this:

http://www.youtube.com/watch?v=o7OH-Q2Vl6Y

I would make the windward side with the band saw as I did in my video. For 3 blades of 1.5 m length that takes about half an hour. The root part and the Lee side I would then make with that kind out router that I showed in the above link an leave about one millimeter of wood on top. It does not have to be too accurate. Again it would only be good to get the rough out of the Lee-side and the the rest done with the power sander. I feel that would be way quicker and cheaper.

I was a lille disappointed when I noticed that this great machine is way over my needs because I would as well really like to build it...but more for the fun of building it rather than for getting the processing speed up.

But if you really want to build that kind of machine I hope you put up plenty of pictures up and mae a video of it working :-)

Max

Radman1 · « **Reply #69 on:** June 30, 2012, 12:49:21 PM »

Hi all, I built the Piggott six foot 24volt turbine this last winter, to say the least it has had it's ups and downs. I live in Oregon and we get our share of rain in the winter. I carved the blades as described in Hugh's book. They came out OK but it took a lot of lead to balance them. I made the tower out of two 4x4x12 posts, so when it was time to raise the turbine, I drove steel fence posts about three feet into the ground. I never dreamed they could pull out, but the gooey mud let one go and it all came crashing down. Broke the blades and the tail but the turbine was OK. I had been thinking about how to make the blades a little simpler. I started with 2x6 ceder, for the root cut a 6" 15 degree angle in the end, I than cut one side out to give me a nice flat blank about 1/2 inch thick, I next made a cut from the root to the tip down too two inch's. all that was left was a little work with a sharp plane to shape the front and trailing edges. The tower is sitting in a crappy location with to many trees blocking the wind, I guess that's what happens when you live in the wood's. So can you guy's tell by looking at the picture if these blades are right? It has not spun up to enough speed to produce more than five volts.
Thanks for any help, Radman1

jlt · « **Reply #70 on:** June 30, 2012, 01:24:10 PM »

You need to bench test the alternator to check the cut in rpm. It should reach charging under 300 rpm.Also check out the angle on your blades from the picture it appears to have too steep of angles. You need only about 1.5 degrees of angle at the tips.
Getting it up above the trees will help a lot .

Radman1 · « **Reply #71 on:** June 30, 2012, 02:06:17 PM »

Hey Jlt, thanks for the reply. What is a optimum angle at the root? These blade are a snap to make on a bandsaw and I can cut any angle I want. I know it will put out the juice but a good site is a huge issue on this land. I built the tower so I can go up and down by my self, I made a steel sleeve to connect the 4x4's together and it seems to work OK but I am a little nervise about adding one or two more 4x4's to get above the tree's. As you know, when the tower is on the way up or down and is hanging out there at 30 degrees or so, it's just a lot of damn weight on the ankers and wire. I could not believe that post came out of the ground last winter.
Radman1

Menelaos · « **Reply #72 on:** July 22, 2012, 05:55:34 AM »

some time has passed...has anyone except me tried to male blades the "one side" way...?

Max

scoraigwind · « **Reply #73 on:** July 22, 2012, 04:21:47 PM »

hi Max,

I believe that Dan Bartmann mostly uses this approach when making smaller blades. He has the sloping leading edge like that. Cuts both the drop and the thickness at once.

I gave it a try last month for a small set of 2 metre diameter blades we built as part of a workshop in Ireland. You can see photos and a video on my blog. http://scoraigwind.co.uk/2012/06/workshop-in-leitrim-with-eirbyte/

It went pretty well. Most of the work was done by one guy (he got hooked on it), and I did not also teach him my usual method (since it would be unfair to confuse him) so it's hard to tell whether this was easier, but it went well. I am still a little bit uncomfortable with it still since the shape of the section is a bit different from what I usually aim for, due to starting with a wedge shaped piece, but I am pretty sure that it's only a problem for me and not a real problem so thanks for your input.

all the best,

Hugh
Hugh

Menelaos · « **Reply #74 on:** July 23, 2012, 07:31:39 AM »

various browsers tell me that the server is down, so I cannot have a look at your block...will try again in the evening...

Max

Menelaos · « **Reply #75 on:** July 23, 2012, 08:33:13 AM »

Was able to see it now...looks like you have had a good time :-)
I wish I was there just for the fun of it !

Are those blades flying already?

scoraigwind · « **Reply #76 on:** July 23, 2012, 05:35:28 PM »

we got a few hundred watts out of them but we had to take them down again. It's a ferrite alternator on that one and I like it. Simple and strong.

Menelaos · « **Reply #77 on:** July 23, 2012, 05:42:32 PM »

Why did you have to take them down...? What happened to the blades?

With ferrets, don'T you often get runaways...?

scoraigwind · « **Reply #78 on:** July 25, 2012, 03:57:02 PM »

We only put it up to test it for the people who had built it. This was not a permanent site. I hope it will be tested for longer soon. Seems like a nice machine!

I have loaded a lot of ferrites into the alternator and it has much more torque than my earlier ones, when ferrite magnets were expensive to buy. So I don't worry about it running too fast, but it does run a bit faster than a neo one, and that is actually good for the performance.

Anyway I have a lot of neighbours with the early ferrite machines and they have run very nicely for many years with modest outputs and happy owners.

SparWeb · « **Reply #79 on:** August 16, 2012, 07:19:38 PM »

Quote from: Menelaos on July 23, 2012, 05:42:32 PM

With ferrets, don't you often get runaways...?

Was that lost in translation, or did I miss the joke?

bob golding · « **Reply #80 on:** August 17, 2012, 02:43:45 PM »

just been reading some of this thread while i wait for the weather to improve. serves me right servicing the turbine in august.

i noticed on the pics from Ireland that Hugh posted of the one sided carving that there is a very steep angle to the root. i have always made the angle as shallow as possable. i cant see the point of having a sharp transition to the root,as there is not a lot of energy to be found in the inner part of the blade.
any one explain the thinking behind the sharp transition?
i am going to have to make a new set of blades at some point so am very interested in peoples thoughts on blade design.
all my blades have basically worked fine so it seems to me unless you have some way of testing your alternator on the bench it is a difficult to see if there any differences.

but that's just me if it works i am happy.

khloreen · « **Reply #81 on:** October 06, 2012, 02:24:11 PM »

Hi max!
I am working on a turbine of mine, I got the piggott book went through but found it a little difficult to understand the blade fabrication, I however came across your video online, and really like the work you put into the video, it was very understandable.
My question is
Have you tested that blade? And if you did was it as efficient as that of piggott?
Thank you in anticipation.

Menelaos · « **Reply #82 on:** October 07, 2012, 06:40:52 AM »

I myself have not tried them yet but I made some sets for other people that are happy with the blades. The way I cut the blades will not effect the efficiency. All the angles and stuff are the same...
Anyway, those Piggott-blades are not on the top end of efficiency. They are easy to build, solid and run well, what more do you need. If there were differences, they would be too small to be really noticeable.

If you want an perfect blade ( whatever this means...) than you have to male a lot more effort and spend some money...

Max

khloreen · « **Reply #83 on:** October 07, 2012, 11:52:44 PM »

Thanks max.

stag · « **Reply #84 on:** February 10, 2013, 08:15:00 AM »

Back to the original question. How much simplification do you want. The ultimate in simplicity is an untwisted,untapered blade. And they work very well,given a good profile. It also has got to be much easier to get them all the same shape and weight.than hand carved twisted blades. If the outer two thirds of the blade provide 90% of the power,and outer one third 50%,with little twist in this area, then why bother with twisted blades at all. It may make aerodynamic sense to have some taper giving a higher aspect ratio nearer the tip which is travelling faster,but it's debatable how much difference this might make. The setting angle can be as small as 4 degrees for speed with ,maybe wedges glued on near the root to increase the angle and assist start up. I respect the knowledge and experience expressed in above posts,but even though I am an experienced woodworker/boatbuilder and have the neccesary tools, I can't see myself carving twisted blades any time soon.

Menelaos · « **Reply #85 on:** February 10, 2013, 08:30:55 AM »

The problem with untwisted blades is that they are not that easy to make from wood. When it comes to Glas fiber blades I agree but with wood you then have a lot of weight on the tip section and the blades have to be quite thick and wide...too much and if you make it less in width you lack stability.

I now do my blades with the chainsaw...but also a one-cut version. I woll soon upload a video on youtube.

Max

stag · « **Reply #86 on:** February 10, 2013, 08:45:58 AM »

Fair comment. I forgot to mention that having been a boatbuilder I make GRP blades,but had considered using wood in my next project.

mallikarjun · « **Reply #87 on:** February 14, 2013, 02:42:51 PM »

Hi This is Mallikarjun

I'm a student ,we r doing a project on axial flux permanent magnet generator for wind power

i am using magnets of trapezoidal shape magnets(NbFeB) of

with dimensions of outer diamater 60mm xinner diameter 47.5 X height 39.5mm and thickness 5mm

magnet grade 42 of NbFeB

since i m doing 8 pole rotor and stator would be star connected and i am using 12 coil for stator
i need know about how many turns per coil should be used for 300watts capacity and the gauge of wire
speed would range for 350-400rpm

please help me out

JW · « **Reply #88 on:** February 14, 2013, 06:39:22 PM »

Hi All, just checking to see if this thread is posting from the newbies section.

I see Bruces logic moving this topic, its basic (the topic) good thing for new users to familiarize themselves with..

JW

Menelaos · « **Reply #89 on:** February 26, 2013, 08:56:33 AM »

As I promised, I did upload a video on making the blades with a single cut chain saw method, so here it is:

http://www.youtube.com/watch?v=aTloL-j5BSY

Max

midwoud1 · « **Reply #90 on:** February 26, 2013, 05:33:06 PM »

Hi Max.
Great work.

- Frans -

Menelaos · « **Reply #91 on:** February 26, 2013, 08:16:53 PM »

Thanks.
It does work ok but I prefer the band saw method over this one. You can see the problem in the video as well:

If you get close to the root of the blade, you have to make several passes to get the correct twist. The blade of the chainsaw tends to lift off from the guide rail on the trailling edge. This is because on the leading edge side of the blade the chainsaw blade has an angle going upwards but has to go downwards on the trailling edge side. So you have to twist the saw blade to get that done. Using the piggot Style blade and applying the chainsaw method to that one, the problem is not that bad as the leading edge is on the same level all the time. Doing it my way it is the back side of the chainsaw blade that has to rip off the material near the root of the blade. This results in the blade becomming blond quickly and you need a lot of power as you always have to press down the tip of the saw blade. I have now mounted a handle near the tip of the chainsaw blade. This way it is possible to push the saw sideways which saves a lot of human power and helps reducing the number of passes towards the end. BUt still after a set of 3 blades the chain has to be replaced or sharpened...ok...it costs about 5 bucks so no problem but I wanted to mention.

As the band saw blade is a lot less in width, that problem is not an issue there.

But finally if you apply a handle on the saw blade it is a fast way of making a blade and having to make only one jig saves time and also space in the work shop.

Max

Frank S · « **Reply #92 on:** February 27, 2013, 01:12:41 AM »

when I saw the video I was going to ask you why you didn't add a handle
some guys who do a lot of chainsaw sculpture will have a special bar that they have ground supper thin allowing them to twist the bar out of shape and use bow bars for weird and special cuts

Menelaos · « **Reply #93 on:** February 27, 2013, 01:35:04 AM »

well that would be a good solution...do you have an example for such a blade, I guess that that would be quite costy...?

Anyway, it also works with my standard blade in combination with the handle attached. With that one it is possible to get at least some flex ( you cannot get any if you do it without handle like shown in the video ) and you can push the blade down.

I can live with it. If I am planning on making 50 Sets of blades, I would have them water jet cut the same way that I use the chainsaw now, use a simple copy carver to make the leading edge side on the lee side at maybe 4 Stations and interpolate between them manually with a drawing knife and band saw...or use a 3d water jet machine to make those guide marks on that lee side...that would be the first cuts...then turn around and make the windward side. It is easy to adjust on the table as the lee side remains flat :-)

That should not even be expensive when we are talking about 150 pieces to maybe offer to people to finish themselves. But here in Germany, wooden blades are not that common and we have funny rules that make it hard to get permissions to put up turbines and expensive so it would not be worth its...and not as fun as making it the ways I showed here ;-)

Max

Frank S · « **Reply #94 on:** February 27, 2013, 05:55:34 AM »

No I don't have an example I only saw this one guy doing speed sculpture at a loggers competition back around 1993 His whole chain saw was homemade he looked like Edward scissor hands the way he maneuvered that thing it was driven from 2 flex shafts 1 running down each sleeve of his jacket the tools and bars were quick connect so he could switch from using 1 or 2 tools the bow or one of several bars the engine was on a back pack it looked to be a motorcycle engine of some kind hard to tell what it was
the 1 flexible bar he had was about 24 inches with a handle out near the end It looked like it would have been really tough on the chain and the bar to bow it and twist it like he did I think he lived somewhere in Oregon

Menelaos · « **Reply #95 on:** March 03, 2013, 03:45:16 PM »

has actually anybody tried to reproduce my single side method...?
I would be interested in the results...

Max

bob golding · « **Reply #96 on:** August 16, 2013, 06:18:31 AM »

Quote from: Menelaos on March 03, 2013, 03:45:16 PM

has actually anybody tried to reproduce my single side method...?
I would be interested in the results...

Max

i have to make a new set of blades soon so will give your method a try. i have always used windstuffnows figures before so time to try something new. i am in a high wind area so any shape will work around here. wind is mostly in the 30 to 80 mph range in the winter. i am using solar at the moment so have plenty of time to play with the blade carving.

doodadyoung · « **Reply #97 on:** February 09, 2014, 09:22:55 AM »

Fellow blade makers,
I have just finished my third blade using Max's chain saw method. It was very fast! I modified a 14" electric chain saw by cutting out the center of the bar to allow it to twist and follow the guides perfectly.

I allowed 1/8" extra to remove the saw marks and to get the slope perfect. I used a hand plainer, Block plain, belt sander and finished it off with a hand sander. I used the single cut for the thickness and the twist. with 3 stations. All in all total time not counting setting up the jig I have less than 2 hours in each blade.

I will be glad to share if anyone is interested

Menelaos · « **Reply #98 on:** February 09, 2014, 07:04:12 PM »

Looks great!

Nice to hear it worked out for you.

I also modified my chain saw the way you did and I also placed a handle near the tip of the blade which makes it easier and more safe to guide it.

Looking forward to see your blades flying!

Max

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Author Topic: Piggott Blades simplification possible? (Read 95262 times)