Author Topic: Piggott Blades simplification possible?  (Read 36716 times)

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khloreen

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Re: Piggott Blades simplification possible?
« Reply #81 on: October 06, 2012, 12:24:11 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

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Re: Piggott Blades simplification possible?
« Reply #82 on: October 07, 2012, 04:40:52 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

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Re: Piggott Blades simplification possible?
« Reply #83 on: October 07, 2012, 09:52:44 PM »
Thanks max.

stag

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Re: Piggott Blades simplification possible?
« Reply #84 on: February 10, 2013, 06:15:00 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

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Re: Piggott Blades simplification possible?
« Reply #85 on: February 10, 2013, 06:30:55 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

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Re: Piggott Blades simplification possible?
« Reply #86 on: February 10, 2013, 06:45:58 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

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Re: Piggott Blades simplification possible?
« Reply #87 on: February 14, 2013, 12:42:51 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

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Re: Piggott Blades simplification possible?
« Reply #88 on: February 14, 2013, 04:39:22 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

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Re: Piggott Blades simplification possible?
« Reply #89 on: February 26, 2013, 06:56:33 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

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Re: Piggott Blades simplification possible?
« Reply #90 on: February 26, 2013, 03:33:06 PM »
Hi Max.
Great work.

- Frans -

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #91 on: February 26, 2013, 06:16:53 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

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Re: Piggott Blades simplification possible?
« Reply #92 on: February 26, 2013, 11:12:41 PM »
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
I live so far outside of the box, when I die they will stretch my carcass over the coffin

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #93 on: February 26, 2013, 11:35:04 PM »
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

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Re: Piggott Blades simplification possible?
« Reply #94 on: February 27, 2013, 03:55:34 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
I live so far outside of the box, when I die they will stretch my carcass over the coffin

Menelaos

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Re: Piggott Blades simplification possible?
« Reply #95 on: March 03, 2013, 01:45:16 PM »
has actually anybody tried to reproduce my single side method...?
I would be interested in the results...

Max

bob golding

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Re: Piggott Blades simplification possible?
« Reply #96 on: August 16, 2013, 04:18:31 AM »
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.
if i cant fix it i can fix it so it cant be fixed.

doodadyoung

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Re: Piggott Blades simplification possible?
« Reply #97 on: February 09, 2014, 07:22:55 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

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Re: Piggott Blades simplification possible?
« Reply #98 on: February 09, 2014, 05:04:12 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

doodadyoung

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Re: Piggott Blades simplification possible?
« Reply #99 on: February 09, 2014, 06:25:22 PM »
It will be a while before they are flying. I am starting on the mounting frame and the magnet disks next. I started with the blades first after seeing your post and the chain saw method. It was fun making them, I wish it had more blades to make! I am an R/C pilot and have made my own props on my giant scale planes. Thanks for your innovating thinking on this one. Good job