Author Topic: GOE222 /table saw??  (Read 44354 times)

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bcalmed

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GOE222 /table saw??
« on: April 17, 2011, 02:00:20 PM »
I've been lurking for a couple years and have an ECM with PVC blades limping around and around. It's just for fun, no furling, but it actually generates some power. I've begun to realize that, at some point, I've got to make/buy some real blades and get the RPM's up where they belong. The existing blades are 32" each for an overall diameter (with hub) of about 68". I believe this is probably too big for the speed the ECM needs.

I (sort of) get the blade carving thing for the Dan's and Hugh's blades, but I'm intrigued by the GOE222 profile.

I think I may have come up with an idea that might make carving the profile fairly easy.

I'm sure you all will tell me if I'm right, half-right, or nuts.

Here's the idea - based on a finished 2x4 blank...

* GOE222.pdf (14.58 kB - downloaded 1195 times.)

I've got way too many stations listed for a 2x4, I know, but I imagine it could be scaled up and then they might be useful. I did it in inches 'cause that's how I started. I suppose someone smarter than I could put these numbers in a spreadsheet (whatever that is) and make it automatical, but that's out of my league.

I plan on trying this on a cedar 2x4x96 and kerfing the whole length. I'm lazy, so I'll cut the kerfed blank into my finished lengths and fill the kerfs with glue or something for the area where the blades attach to the hub. One board should make balancing easier (I think), and will mean only however many passes per side rather than 3X. I'm going to start with ~32" blades because I can always make them shorter. I expect I'll end up at 24" or thereabouts.

I'll post pics of the carnage when I've finished...

,,,or given up.


bcalmed

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Re: GOE222 /table saw??
« Reply #1 on: April 17, 2011, 04:33:42 PM »
BTW,

Here's the deal for a 2x6 @10 degrees with stations at 1/8" intervals with kerf depths in millimeters...

* GOE222_2X6.pdf (24.74 kB - downloaded 722 times.)

bcalmed

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Re: GOE222 /table saw??
« Reply #2 on: April 17, 2011, 04:55:51 PM »
Bear in mind that I've never used a table saw in my life - I'm scared respectful, very respectful of them. I have no idea how finely the depth is controlled. I know there's a crank, but ...

Originally, I thought that one might cut the kerfs far enough apart to leave supporting material sufficient to support the piece while kerfing and then sand, grind, chisel, drawknife, use high explosives to remove the excess. This woulld work much like the Dan's/Hugh's process for blade carving.

Now I think, with a couple of blades ganged and a jig of some sort to clamp the material, one might be able to just saw all the excess away; leaving a minimal sanding job to finish. This process may only be possible for one side, but, with a jig that's contoured to one or the other, both faces might be doable.

Lazy, I know...

SparWeb

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Re: GOE222 /table saw??
« Reply #3 on: April 17, 2011, 06:29:26 PM »
I tried power saws on my blades.
Things happen too fast for my reflexes that way.

Just my experience, but I find that sawing by hand through the cedar is so easy, that whatever I gain with the power tool is small compared to the time spent fussing about to set them up (and filling the mistakes).

The choice is affected by the size of blade you're considering, which is how you get guys like Oztules cutting 8' long blanks with a chainsaw to build a 16' rotor.
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bcalmed

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Re: GOE222 /table saw??
« Reply #4 on: April 17, 2011, 06:59:31 PM »
Just my experience, but I find that sawing by hand through the cedar is so easy, that whatever I gain with the power tool is small compared to the time spent fussing about to set them up (and filling the mistakes).


I get that about the tapered/twisted blades, but I'm talking about the no/no variety and sawing lengthwise to depth on a blank. I don't have a hand saw that long...  ;D

opo

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Re: GOE222 /table saw??
« Reply #5 on: April 17, 2011, 08:18:18 PM »

I do not know how difficult it will be, but I had exactly the same idea for carving no twist, no tapper blades with the GOE222 profile: using a table saw, which I don't have yet but it is in the near future plans (a press drill and also a band saw are also in the plans).

I also wonder how rough the end product will be and if the thin trailing edge will hold up to the tablesaw abrasive disc. But other than that I think it may work, it could produce a very good approximation of the profile.

Cheers
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klsmurf

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Re: GOE222 /table saw??
« Reply #6 on: April 17, 2011, 08:51:24 PM »
I would expect that with a good table saw, good set up practices and patience, you could get a decent rough cut of the profile. You will still have quite a bit of gouge, spoke shave and scraper work to do then.
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bcalmed

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Re: GOE222 /table saw??
« Reply #7 on: April 17, 2011, 10:08:22 PM »
You will still have quite a bit of gouge, spoke shave and scraper work to do then.

Some hand work, but far less than taper/twist blades, don't you thiink? I don't know why 'd need the tools you mention - remember, I'm shooting for 32" blades - not 8 footers. A close look at the clearly-drawn profile on the end grain should actuallly be all I need - the measurements would be superflous - now that I think about it. 

After all, the kerfs are there and closely spaced - just a get 'to the bottom of it' sort of thing. Almost 2D, I'd say. I'm betting that a 4" disc grinder and a 6 - 12 inch long section of the inverse of the curve as a sanding block and some 80 grit would make short work of it. CVG cedar is pretty easy to work. and there won't be much '"meat" to remove - just 'fins and nubs', if you will.

The nut of it is that I'll have GOE222 blades when I'm done.

ghurd

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Re: GOE222 /table saw??
« Reply #8 on: April 17, 2011, 10:25:33 PM »
I have to wonder about the existing blades.
Do they follow a good design, or do they sort of look like others you saw in so photos?
They could simply have problems in the design.

The ECM is now wired by removing the star point and rectifying the 3 phases individually?
The 12V cut in RPM somewhere around 110~125 RPM?  That is awfully slow.
The blades could be sort of stalling (though I feel PVC type blades are "sort of stall resistant").  That is they can not get turning fast enough to be efficient because the load is applied to soon. 

If you still have some of the PVC around, and the existing set is 3 blades, might try making it into a 6-blade.
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windy

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Re: GOE222 /table saw??
« Reply #9 on: April 17, 2011, 11:39:28 PM »
bcalmed,
  I am thinking of trying to make a set of GEO222 blades@10 degrees, for my 16 foot diameter mill using a table saw but can't seem to find how to figure the profile. Could you let me know how you figured, or where you got the diagrams for your 2x4 and 2x6 blades? I don't think that a 1.5"x5.5" would be thick enough or strong enough for an eight foot blade. Thinking that a full 2"x8" blank may be heavy enough, but not sure.
 I know I can buy a set but that's no fun!

windy
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bcalmed

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Re: GOE222 /table saw??
« Reply #10 on: April 18, 2011, 12:27:31 AM »
G-

Yes, the existing blades are ugly. They start easily, but never seem to 'wind up' liike (I think) they should. I should add that they're not exactly in "clean air" since they're only about 15' up in a turbulent area. However, from one direction (North), the wind is unobstructed and, even when we get a good breeze - 12 - 18 MPH - the blades just don't "take off".

I'll post pics of the blades tomorrow and suffer the slings and errors...

Yep, the ECM is separated at the * point and each of the 6-coil phases has its own bridge. The most I've seen is 4A into a semi-dead deep cycle battery. I've got no logging nor much in the way of test equipment - a couple HF DVM's and an infrared (or ultraviolet) tach. The mill is down now while I build a 35' tower. I've spun the ECM with a drill to ~350 RPM and get about 28Voc through the bridges at that speed.

I just think that, with the low current I've seen when the wind is 'good', that the blades are the culprit(s).

Of course, I haven't been able to measure the RPM's on the tower, so I'm just guessing.

bcalmed

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Re: GOE222 /table saw??
« Reply #11 on: April 18, 2011, 12:35:52 AM »
windy,

I just found the GOE222 profile and stuck it on a box representing a finished 2x6 in a vector graphics program (CorelDraw). I put the basic profile in the box and turned it X degrees and roughly centered it. Then I supeimposed vertical lines at 1/4" intervals and "cut" the lines with the profile. After that, I just read out the lengths of the lines both above and below the profile.

I don't really know much about this, but it seemed reasonably simple.

If you'd like me to figure the measurements for a blank, just PM me with the size.

-bcalmed

ghurd

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Re: GOE222 /table saw??
« Reply #12 on: April 18, 2011, 08:57:56 AM »

I'll post pics of the blades tomorrow and suffer the slings and errors...


I just think that, with the low current I've seen when the wind is 'good', that the blades are the culprit(s).


I enjoy making fun of bad blades!  LOL
Nobody's first set of blades looked very good.  My 50th set didn't look very good.  I bought my only good looking blades.

Is the ECM the type with 18 easy to see separate coils on white plastic?  I would expect more amps from a 1HP wired that way.

If the ECM the very old type with windings that don't look a whole lot different than a regular motor?  I would still expect more than 4A in good wind from a 1HP, but I have a feeling that type would peak out (plateau) at a lower amps.

You may be at the point where it peaks out when wired that way.
This is a new type 1/3~1/2 HP with just the star point cut and all 6 wired rectified.


Or in stronger wind, the long PVC blades may be bending goofy so they can't go faster, sort of self-limiting RPM.
Usually my  bending PVC blades get noisy with buzzing, flapping sounds, but mine are smaller and spinning pretty fast.

Best bet, IMHO, is to do the surgery separating the coils into groups of 3.

I believe fast wood blades will stall with the way the ECM is wired now.
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bcalmed

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Re: GOE222 /table saw??
« Reply #13 on: April 18, 2011, 11:25:27 AM »
It's a GE 1HP with the white plastic. Looked brand new when I got it (free) - just didn't have the 'brain'. All three phases show the same resistance ~3.? ohms, if I recall correctly. The blades were cut from a piece of 10" PVC light green sewer pipe. They will bend, but that stuff is about 3/8" thick so they're not really 'flappy'. I do know they don't track accurately, so there is some noise - but not bad. The other issue may be the 'angle of attack', if that is the right term - the leading edge is not exactly smack down on the metal and so that may be another problem.

PS, don't eat before you look at these...




« Last Edit: April 18, 2011, 11:31:53 AM by bcalmed »

opo

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Re: GOE222 /table saw??
« Reply #14 on: April 19, 2011, 01:24:03 AM »
your blades look like fast blades. They probably reach cut in speed in slower winds. But because the winds are not strong enough they do not carry enough energy to crank your alternator to higger amps hindering your blades to keep speeding up to their happy rpm speed.

If you have enough pvc left to make another set of blades then go with fatter blades and probably add an inch, maybe more, to their length.

I find carving the 222 profile to be a non trivial project, but I want to give it a try too.
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ghurd

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Re: GOE222 /table saw??
« Reply #15 on: April 19, 2011, 10:53:04 AM »
When they are flat on the floor, like in the pic, look at the blade tips.

Could be the tip, and quite a bit of the length, are not really doing any good.
A ' u ' shape with the leading and trailin edges both pointing up is a common problem with not getting any power out of them.
Need sort of a ' j ' at the end...  '  _/ ' ... ?

If the leading and trail edges both point up from the floor, then the 2 parts are fighting each other.
And it can get worse when the wind bends the blade back even a little.
I bet they have both those problems.

I don't think it needs super fancy blades, it just needs better blades, even if they are PVC.
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Norm

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Re: GOE222 /table saw??
« Reply #16 on: April 19, 2011, 01:36:50 PM »
When they are flat on the floor, like in the pic, look at the blade tips.

Could be the tip, and quite a bit of the length, are not really doing any good.
A ' u ' shape with the leading and trailin edges both pointing up is a common problem with not getting any power out of them.
Need sort of a ' j ' at the end...  '  _/ ' ... ?

If the leading and trail edges both point up from the floor, then the 2 parts are fighting each other.
And it can get worse when the wind bends the blade back even a little.
I bet they have both those problems.

I don't think it needs super fancy blades, it just needs better blades, even if they are PVC.
G-
G, It looks to me that his blades should have been made from larger diameter PVC?
like maybe twice the diameter. That's the trouble I had making blades for a treadmilll motor.
using 8" PVC ....tried flattening the blades, but nothing works quite as good as using the
right stuff in the first place.
Norm.

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Re: GOE222 /table saw??
« Reply #17 on: April 19, 2011, 07:21:00 PM »
Carving blades from a single piece of wood, like a 2x4 or 2x6 can also be problematic, even though a 2x4 is dead, unless it is very dry and sealed VERY well it sure wont act dead.
It looks from the picture like the only part of of those blades doing any work would be the root, that's gonna be the reason for the rpm problems.
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bcalmed

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Re: GOE222 /table saw??
« Reply #18 on: April 20, 2011, 11:15:34 PM »
Hey windy,. here ya go...

* GOE222_2.pdf (22.7 kB - downloaded 480 times.)

windy

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Re: GOE222 /table saw??
« Reply #19 on: April 22, 2011, 11:07:00 PM »
bcalmed,

 Thanks for the file. I'm going to try it on a short blank to see how it works. But looking at it, it should be doable with a table saw.

windy
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bcalmed

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Re: GOE222 /table saw??
« Reply #20 on: April 25, 2011, 12:04:34 AM »
G-

Here are some better pix of the rotor. I see that, although there is a 3-4 degree pitch at the tips, the leading edge is not parallel to the plane of the rotor. I'll try to remedy that by slotting the mounting hole or fabricating some 'crutches' to bolt the blades to which, in turn, will mount to the hub.

I tested the cutin more carefully this wwekend and it's 12.8 Voc @ 160 RPM. I suspect, as you say, that's too slow for the ECM as wired. Is it correct to aasume that if I wire it series/parallel (parallel three of the former six coils with the other three in each phase) that the cutin speed would double? I have a little DC/DC booster module [ Attachment Invalid Or Does Not Exist ] that begins to boost at 9.5 VDC and has adjustable output by turning a little multiturn pot. This gizmo purports to be able to pass 150W, but heats up a bit at 5A when I connect its input to a battery and its output to another semi-discharged battery. I don't know about the volts/amps deal as far as the ECM and the gadget are concerned. I (sort of) get that excess voltage over cutin voltage is (magically) converted to charging current, but, I sense that there's a range beyond which there are diminishing returns.

So, if I rewire as I mentioned, what should I shoot for with the booster [ Attachment Invalid Or Does Not Exist ] ? I'm guessing that the power of the blades at any given RPM is the factor I need to watch. Since the gadget/gizmo is adjustable, should I just fire it up and watch the RPM's - taking what power there is without 'stalling' the blades - until the ECM's unboosted output hits cutin?

Thanks,

Rick

[ Attachment Invalid Or Does Not Exist ]
[ Attachment Invalid Or Does Not Exist ]
[ Attachment Invalid Or Does Not Exist ]

bcalmed

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Re: GOE222 /table saw??
« Reply #21 on: April 25, 2011, 02:24:15 AM »
Screwed that up...

What's new?

da pix:





SparWeb

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Re: GOE222 /table saw??
« Reply #22 on: April 25, 2011, 11:46:40 AM »
In the pictures, the leading and trailing edges look rather "square".
A big improvement would be to bevel the trailing edges.
Rounding the leading edges will help too.
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
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bcalmed

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Re: GOE222 /table saw??
« Reply #23 on: April 25, 2011, 12:33:18 PM »
Which face do I bevel on the trailing edge - windward or leeward?

-Rick

opo

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Re: GOE222 /table saw??
« Reply #24 on: April 25, 2011, 02:06:44 PM »
Which face do I bevel on the trailing edge - windward or leeward?

-Rick

This is what I would bevel (sort of)



The blue is the size I would use instead, i.e. fatter blades.

Cheers

Octavio
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Re: GOE222 /table saw??
« Reply #25 on: April 26, 2011, 10:25:02 AM »
I might have missjugded the leading edge in your picture. If it is on the right then you'll have to flip the airfoil horizontally from the picture.

Opo
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Re: GOE222 /table saw??
« Reply #26 on: April 26, 2011, 04:48:18 PM »
I'm pretty sure that the the leading edge is on the right of the photo, so Opo has it drawn backwards (by his own admission).

The left is the trailing edge, and I think you could bevel both windward and leeward of the trailing edge, for a no-net change to the angle of attack. 
No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
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ghurd

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Re: GOE222 /table saw??
« Reply #27 on: April 27, 2011, 02:15:33 AM »
While opo's sketch looks reversed to me too, the concept is still valid.

My gut feeling is that when the wind is pushing on the blade, the tip (and more) will go negative or close to negative, and that is bad.
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bcalmed

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Re: GOE222 /table saw??
« Reply #28 on: April 27, 2011, 11:47:25 AM »
Well, here's what I plan to do to the blades/rotor while I explore making the GOE 222 blades from 2x6 CVG cedar.

1) Round the leading edges and taper the trailing edges - trying to make the constant (more or less) chord part of the blades into an airfoil shape. I probably wont mess with the inner third.
 
2) Re-drill or slot the mounting holes on the blades to increase the pitch as much as possible. I'll probably fabricate some PVC 'shims' and glue them to the underside mounting surfaces for more support..

3) Carefully re-check tip-to-tip equalization and tip tracking, re-balance and re-mount. The new tower is almost ready.

4) Cobble together a bike speedometer tach and buy/make an anemometer to check TSR.

5) See what happens...

I'm still considering re-wiring the ECM to 3/3 phases and using the little booster module http://cgi.ebay.com/DC-10-32-OUT-12-35V-150W-adjustable-boost-converter-/120656554215?pt=LH_DefaultDomain_0&hash=item1c17b0e8e7. I need to figure out some sort of over-voltage/current protection as it has none.

Unfortunately, my electrical engineering degree is non-existent.

Any suggestions would be welcome.

Thanks,

Rick


windy

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Re: GOE222 /table saw??
« Reply #29 on: April 28, 2011, 11:51:49 PM »
bcalmed,

 Returning the favor for helping me with the blade profile of the 2.25"x 8" blade.
I tried making a blade from a 2x6 using a table saw and I would have to say that it will work. I spent about 2 hours sawing one blade, but once you have the saw set you should be able to make the cuts in all three blades, so it shouldn't take that much longer for all three.  Also, the saw fence has to be long enough and rigid enough for an accurate cut. And a sharp blade.


 Here is the blade after shaping. I tried using a hand plane but that didn't work very good, so I put a sanding disk in my 4" Dewalt side grinder and it took just a few minutes to get it down to the rough shape. Tried breaking off some of the waste wood, but it broke below the saw cut.


 This is the front of the blade. When I got close to the bottom of the saw cuts, I sprayed the blade with black paint so I could see how deep to grind with the side grinder. After that, you can just sand by hand until you remove the paint. I just sanded the end to see how the profile looks from the end. The black lines are from the paint in the bottom of the saw cuts.


 This is the back side. A little trickery to grind because of the inward curve, but not impossible. I just carved this blade to see if it can be done. I think a 5 foot long blade should work too, if the fence is long enough on the table saw.


 This is only a 3 foot blade using a pine board. Being that the blade is no good for anything, I will weight it down and see how many pounds I can hang on the end before it fails. I will post the results.
 I am still thinking of trying an 8 foot long blade, but that may be a winter project!

windy 

« Last Edit: April 29, 2011, 12:21:48 AM by windy »
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Re: GOE222 /table saw??
« Reply #30 on: April 29, 2011, 12:42:14 AM »

Hey windy, congratulations! and thanks for sharing the good news. Painting the groves is a very good idea, it tells you where to stop sanding/grinding.

Could you please post a picture of your table saw setup?

Thanks again,

Octavio
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bcalmed

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Re: GOE222 /table saw??
« Reply #31 on: April 29, 2011, 02:45:44 AM »
OK, I'm blown away!

I am soooo glad you did this and it seems to have worked - I have to use my neighbor's table saw and that won't happen 'til the middle of May.

Meanwhile, you've proven the concept. Sort of a CNC without those letters.
Two hours/four hours, but - GOE222 profile!
Just what I'd hoped - a synthesis of cheap, easy and low-tech.

Thank you, thank you, thank you!

-Rick

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Re: GOE222 /table saw??
« Reply #32 on: April 29, 2011, 05:13:19 AM »
How did you remove the remaining wood in the first picture. I did not get that from your description (perhaps just overlooked it).