GOE222 /table saw??

[Dave B]

bcalmed & windy,

  Very creative and super job. It takes time and a bit of patience and I salute your resourcefulness. You certainly have opened the door to anyone with a decent table saw knowing that they can custom cut any profile this way. Again, great job and be sure to post photos of a completed set. Thanks for sharing,  Dave B.
 

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.
(Attachment Link)

 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.
(Attachment Link)

 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.
(Attachment Link)

 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.
(Attachment Link)

 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 

[windy]

opo

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

opo,
 
 I just have 10" Delta contractor table saw. No special setup. I just moved the fence a quater inch at a time and adjusted the blade height using a digital caliper. I always measured from the back of the fence, on both ends, to the outside of the table to make sure that the fence is parallel to the blade. I also had to make a stop to keep from sawing into the root of the blade. I just set the table saw close to a wall so that the end of the blade hits the wall after each cut. As long as you don't move the table saw, all the cuts will line up when you are done. I also shut down the saw before lifting the board off the blade to keep from sawing into the waste wood.

windy

[windy]

How did you remove the remaining wood in the first picture. I did not get that from your description (perhaps just overlooked it).

XXLRay,

 First picture, I used a table saw. Second picture , I used a Dewalt 4-1/2" Flap Disk (Model #DW8308) on a side grinder. They are available from 36 to 120 grit. I used the 60 grit and it really takes the wood off without any burning of the wood. I would also get the 120 grit for when you get down to the bottom of the saw cuts. You really have to take it easy using the 60 grit. Cost is about 8 or 9 dollars each.
Also, do it outside. It makes a mess in a shed. Fine sawdust over everything.

windy

[SparWeb]

First off: excellent idea!

Second:  Have you thought of a way to make a twist to the shape, as in give it more angle of attack at the root?

Maybe by putting a wedge under the board in the right spot. 
Trailing edge:  Saw cuts deep at the root, shallow at the tip. 
Move the wedge a bit for every successive cut... 
Leading edge: Wedge is moved out of the way so the slot is constant the whole way along.
Flip blade over to do the opposite side, put a new wedge in, but the other way around.

I've probably failed to communicate what I'm thinking with words.

Twist isn't necessary so this could be excess work, defeating the purpose of this much-simplified way of making the blade.

To make the set of (3) blades as identical as possible, each can be passed through for each table saw setting, before adusting the saw blade for the next pass.  Then run all of the blades through again for that pass.  Eliminates the variations in saw blade setting if you set up to do each one all at once, and probably is faster, too.

[XXLRay]

Second picture , I used a Dewalt 4-1/2" Flap Disk (Model #DW8308) on a side grinder.

Just to make sure (as I am not a native speaker) - this is an angle grinder (like this: http://en.wikipedia.org/wiki/Angle_grinder), right?

[jlt]

That's a  neat way  To carve a blade. And do all three the same. Might try using two saw blades stacked together with a thin washer between them.  It would speed things up a bit.

[opo]

And here it goes a little contribution to the table saw blades gang:

I created a little program to perform the calculations for the table saw carving. As input, it takes the 4 digit NACA profile we want to carve, the size of the piece of wood (2x4, 2x6 for example) and  the pitch angle. The output, as of today, is an eleven column list of numbers giving the (x,y) coordinates of the points of the airfoil, upper and lower curves, the next set of columns gives the (x,y) coordinates of the pitched airfoil, upper and lower, then the scaled to size pitched airfoils coordinates, and finally, the lest three columns gives the measures for setting the saw blade for the upper and lower foils.

I assumed a kerf of 1/8" but this could be easily changed to be part of the input.

Here is an example of the program runing for a NACA6616 (very similar to GOE222) airfoil on a 2x6 at  10 deg pitch:

NACA6616
wood dimensions:

       +----------------+
 wh |                       |
       +----------------+
               ww

wh=2.0
ww=6.0
Pitch angle(in deg)=10.0
0.000000   0.000000   0.000000   0.000000   0.000000   0.000000   0.000000   0.000000   0.000000   2.000000   0.158242
0.014756   0.035576   0.026911   -0.027387   0.050122   0.225587   0.187548   -0.133790   0.050122   1.774413   0.024452
0.033651   0.051116   0.049683   -0.035028   0.145579   0.337096   0.330063   -0.155210   0.145579   1.662904   0.003032
0.053323   0.063069   0.071677   -0.039371   0.249367   0.428221   0.464548   -0.157958   0.249367   1.571779   0.000284
0.073432   0.073003   0.093235   -0.041985   0.357835   0.507873   0.594655   -0.150941   0.357835   1.492127   0.007301
0.093836   0.081532   0.114498   -0.043482   0.469514   0.579524   0.721852   -0.137634   0.469514   1.420476   0.020608
0.114459   0.088972   0.135541   -0.044180   0.583621   0.644975   0.846923   -0.119835   0.583621   1.355025   0.038407
0.135252   0.095517   0.156415   -0.044273   0.699666   0.705311   0.970357   -0.098633   0.699666   1.294689   0.059609
0.156181   0.101294   0.177152   -0.043887   0.817314   0.761257   1.092489   -0.074749   0.817314   1.238743   0.083493

...

0.604355   0.120380   0.603978   -0.000393   3.445621   1.340977   3.569222   0.626957   3.445621   0.659023   0.785199
0.626088   0.117794   0.623912   0.001738   3.576730   1.348339   3.684789   0.660314   3.576730   0.651661   0.818556
0.647743   0.114778   0.643923   0.003647   3.707830   1.353082   3.801044   0.692443   3.707830   0.646918   0.850685
0.669317   0.111338   0.664016   0.005328   3.838888   1.355234   3.918019   0.723316   3.838888   0.644766   0.881558
0.690804   0.107480   0.684196   0.006778   3.969874   1.354821   4.035745   0.752908   3.969874   0.645179   0.911150
0.712201   0.103207   0.704465   0.007991   4.100758   1.351868   4.154250   0.781193   4.100758   0.648132   0.939435
0.733505   0.098524   0.724828   0.008963   4.231515   1.346395   4.273561   0.808150   4.231515   0.653605   0.966392
0.754711   0.093436   0.745289   0.009689   4.362119   1.338423   4.393704   0.833761   4.362119   0.661577   0.992003
0.775816   0.087945   0.765850   0.010167   4.492548   1.327968   4.514700   0.858006   4.492548   0.672032   1.016248
0.796817   0.082055   0.786516   0.010393   4.622778   1.315046   4.636572   0.880872   4.622778   0.684954   1.039114
0.817712   0.075769   0.807288   0.010364   4.752790   1.299671   4.759342   0.902344   4.752790   0.700329   1.060586
0.838496   0.069088   0.828170   0.010079   4.882565   1.281852   4.883027   0.922413   4.882565   0.718148   1.080655
0.859169   0.062016   0.849164   0.009534   5.012082   1.261598   5.007648   0.941070   5.012082   0.738402   1.099312
0.879725   0.054552   0.870274   0.008729   5.141324   1.238917   5.133222   0.958308   5.141324   0.761083   1.116550
0.900164   0.046699   0.891502   0.007663   5.270273   1.213810   5.259767   0.974124   5.270273   0.786190   1.132366
0.920481   0.038458   0.912852   0.006334   5.398912   1.186282   5.387301   0.988515   5.398912   0.813718   1.146757
0.940675   0.029828   0.934325   0.004742   5.527224   1.156330   5.515840   1.001483   5.527224   0.843670   1.159725
0.960741   0.020811   0.955925   0.002887   5.655191   1.123953   5.645403   1.013029   5.655191   0.876047   1.171270
0.980678   0.011405   0.977654   0.000770   5.782795   1.089146   5.776006   1.023158   5.782795   0.910854   1.181400
1.000482   0.001609   0.999517   -0.001609   5.910020   1.051901   5.907668   1.031878   5.910020   0.948099   1.190120

And here is the code of the program: Feel free to use it, modify it and improve it, of course, there are no warranties, it certainly doesn't work and contains many errors.

 airfoils.c (2.62 kB - downloaded 296 times.)

compile with
gcc airfoils.c -lm -o airfoils

run with
airfoils


Cheers,

Octavio

[bcalmed]

An idea for the table saw blades in order to minimize the 'finishing' process:

I had originally thought that most, if not all, of the waste could be cut by the saw blade - single, double, dado, whatever. Then I realized (duh!) that, if one doesn't leave substantial (like windy's) 'meat' between the kerfs, the whole thing becomes unsupported and generally the process won't work.

Then I decided that a jig might work better...

 GOE222_JIG.pdf (20.62 kB - downloaded 421 times.)

The first side is easy - since the obverse is flat. The second side would require one or more shims. The contoured "orthotic device" shown isn't really necessary - just a shim the length of the blade at the appropriate point on the profile and secure mounting of the half-finished blank in the jig.

This way, the saw does nearly all the work and the finishing part is minimized.

Of course, maybe the hand finishing would be faster than the saw. It would take, maybe, twice as many passes on the saw to eliminate ~90% of the hand finishing. However, the margin of error would probably be reduced.

Just a thought.

[opo]

bcalmed,

I think leaving two or three legs on each side of the leading and trailing edges would be enough for stability.

Cheers

[bcalmed]

I think leaving two or three legs on each side of the leading and trailing edges would be enough for stability.

I think you're probably right - then you could 'saw away' almost all of the rest of the legs. I'll reserve judgement on that 'til I actually try it, though.

I suppose that the width of the blank would be a determining factor. The bigger the blank, the less (relatively) support those legs would give.

"Wiggly" would not be a good thing...

...as in most endeavours.

[windy]

Second picture , I used a Dewalt 4-1/2" Flap Disk (Model #DW8308) on a side grinder.

Just to make sure (as I am not a native speaker) - this is an angle grinder (like this: http://en.wikipedia.org/wiki/Angle_grinder), right?

opo,

Yes, that is power tool I used.

windy

[windy]

For  anyone trying the saw method,
 My experiment with using a table saw to cut the profile was so simple that before trying to build any kind of a jig, I would suggest that you take a foot long piece of scrap 2x6 and see how it works. One thing that I should have tried to remove the waste wood is, take a sharp utility knife and score the first piece of waste wood, break it off and then score the next piece. If that would work there wouldn't be much left to sand. I think that if you score it deep enough, it should break without going below the saw cut. Another reason to use the 1/8" cut is that you will end up with more reference points when you finish sanding. I think you would end up with a more accurate profile.
 Another thing I should point out is, if you look at my first post, Using table saw.JPG, between the 15th and 16 saw cut, I moved over only a 1/8" and made another cut. The reason i did this was if I continued to cut on the same side of the line, I would start to cut below the profile line. If you draw the 1/4" lines on the end of the board, the blade profile and where the saw will remove the wood, you should see what I am talking about.
 Bcalmed's 2x6 posting has station line every 1/8". I used 1/4" stations and used every other measurement that was posted.

windy

[zvizdic]

Very  GOOD idea!

As proven by Chris 222 airfoil is worth pursuing and coming with a ways to carve .

It puts a good airfoil to easiest to carve.

[ontfarmer]

What thickness and width should be used for a 10 foot blade?

[opo]

What thickness and width should be used for a 10 foot blade?

This has to do with rotor solidity:

Solidity= (# of blades)*(area of one blade) / (Pi*(D/2)^2)

where D is the rotor diameter. If solidity is low (say 0.09) then you should design for high tip speed ratio, low torque blades. On the other hand, if solidity is, say 0.90, then you end up with a high torque, low tip speed ratio rotor.

Cheers,

opo

[bcalmed]

Obviously, this is a stupid question.

Since I'm going to try to make GOE222 blades, I ought to know what this "10 degree pitch" is of which many of you speak. I thought (in my ignorance?) that it referred to the angle at which the "centerline" of the profile differed from the plane of travel of the blades. I realize that, apparently, I don't even know which end is up. I guess I DO know which are the leading and trailing edges, but is it the convex or concave face of the blades that faces the wind? If the pitch isn't the same as the angle of attack, then I'm baffled. Moreover, now I doubt myself about which way the pitch/angle should "rotate" - leading edge windward or vice-versa...

Anyone care to enlighten me?

Rick

[DualFuel]

Hey,
I like the table saw idea, and its obvious sucess.
Does anyone know if the blades could be cut with planer or jointer, whose blades have been milled to the 222 profile?
I thought to cut out a set of blades for the top half. Then another set for the bottom half of the profile. Installing them on two jointers would offer faster production as well.
DF

[SparWeb]

Obviously, this is a stupid question...
Anyone care to enlighten me?
Rick

It's not immediately obvious to many.  For a wind turbine, the "front" is the face you see when looking at the turbine from upwind.  That face of the blade is the "flatter" side of the airfoil.  The "back" is the curved side.

So if you translate that into your mental picture of an airplane wing, the aircraft is going forward and down, and producing lift.  Because we are making wind turbines, the lift in this case makes both torque and thrust.

I'm pretty sure that you can find good diagrams on Hugh Piggott's page - there is a 6-page PDF introduction to WT blades that is VERY helpful.  Somewhere on the bottom in his "old stuff".

[kevbo]

Since I'm going to try to make GOE222 blades, I ought to know what this "10 degree pitch" is of which many of you speak. I thought (in my ignorance?) that it referred to the angle at which the "centerline" of the profile differed from the plane of travel of the blades. I realize that, apparently, I don't even know which end is up. I guess I DO know which are the leading and trailing edges, but is it the convex or concave face of the blades that faces the wind? If the pitch isn't the same as the angle of attack, then I'm baffled. Moreover, now I doubt myself about which way the pitch/angle should "rotate" - leading edge windward or vice-versa...

The "convex" side goes downwind. (opposite of a driving propeller)  The leading (rounded) edge still goes upwind.  Pitch measurement needs to be defined with respect to a datum that varies depending on the airfoil. I don't know what datum is used to measure the 10' pitch with the GOE222 'foil.  

With flat bottom, or cambered airfoils, it is convenient to measure with respect to a stick spanning the concave (or flat) surface, like this model airplane propeller pitch gauge does: http://static.rcgroups.net/forums/attachments/2/4/0/5/9/3/t2586007-238-thumb-prop%20pitch%20gauge_2.JPG?d=1245185240  

It is trickier with symmetric or semi-symmetric airfoils, here is a pitch gauge used with model helicopter rotor blades: http://t1.gstatic.com/images?q=tbn:ANd9GcRyu4bIltz5Jp57jblAu9teqv0YcRLVfs8v_pa8LDpHfwhT8bdREQ&t=1 Note that the airfoil is held between V shaped jaws.

[kevbo]

It appears that the datum for the GOE222 runs from the trailing edge to the farthest point on the leading edge curve.

This shows the airfoil at zero pitch:

http://www.worldofkrauss.com/foils/435

[fabricator]

Hmmmm, I could see a pretty easy to build sled on rails with a router on it to carve blades like this, support would be pretty simple you need un carved stock on the root end for mounting, just leave six inches or so on the tip end too, then just saw it off when done.

[bcalmed]

The router sled would be cool, but you'd still need to manually adjust the X and Z axes for every pass. I just tried to think of the easiest way to do this - with tools I don't have to build (not that I'd be able to). The most 'building' one would need for the table saw approach would be table extensions. Those, I can build from scrap lumber/plywood.

I've toyed with the idea of removable shims to eliminate adjustments to the saw fence, but I think 1/4" shims, one removed after each pass, would introduce way too much inaccuracy AND danger to the process.

I plan to make a dozen or so fixed size shims at 1/2" stations and double up the saw blades. The grinding/sanding bit seems pretty easy if one is at all careful. The paint trick 'windy' mentioned is a great idea. We used to do that at the body shop to point out sanding scratches when finish sanding before paint - it was called a "guide coat". The "height of cut" adjustments might be easier than I originally thought in that the adjustment wheel has a fixed turns/height ration and measurements might not be necessary after a test piece or two - just a 'half-turn/quarter turn" kind of deal. We'll see.

I doubt the performance of this profile will be materially affected by a few wows and gouges here and there - plus, there's always Bondo.

A cut-out template of the profile to slide down the blades will tell the tale - it's: leave it 'fat' and sand a bit more, a lot easier than patching and re-sanding.

After Memorial Day I'll get at it - right now I've got too many tombstones to layout and sandblast. Hey, somebody's got to do it.

-Rick

[DualFuel]

 So I asked a friend who does a lot of wood working...and he told about a wood shaper. Its seems that blank blades can be purchased for them, then milled to the shape you desire. I could see a shaper with two sets of blades cut out for the over and under profile of the 222.
 The table saw is a good plan for one set of blades, but I am thinking more about multiple sets of blades ( up to ten sets).




DF

[ghurd]

"Shaper" was the 1st thing a freind of mine said too.
He has made custom shapes from blank blades several times, and he says it is not difficult.  Not sure how he did it, but he does not have access to a milling machine.  Probably did it with a die grinder?

1st thing I said was "Yea, that will work on the first side, but what about the Other side?"
He claims that is no problem either.  I don't recall his solution.
G-

[zvizdic]

My attempt at GOE222  is to rework 10' Otherpower blades to something close to goe222.

I use angle grinder to grind a concave to front face.

[Royal]

Hi guys,  I finally got caught up to this long conversation on the 222 profile. I thoughtI'd try to clear up a few things.  I currently build the blades that Chris Olson and Dave B use along with many others that I have shipped to many areas of the country. [LINK REMOVED]  First of all you are doing a great job of producing this profile by using a table saw. There is also something called a Dato blade that looks like it wobbles and is adjustable for widths. Might be handy for you.  
    The pitch is generally set at 10 degrees for best overall performance considering RPM and torque.  The pitch is the angle that the chord, the line from the blunt point of the leading edge to the tip of the trailing edge, makes with the plane of the direction of travel.  The angle of attack is the angle that the wind hits the blade compared to that chord line. Standing still and a puff of wind hits the blade the angle if attack will be 80 degrees, considering the chord is already at 10 degrees.  As the blade starts to move forward it changes its own condition. The combination of the wind direction coming straight at the generator and it's forward motion gives you an apparent wind more towards the leading edge.  The angle that this apparent wind makes with the chord is your angle of attack.  Unloaded the 222 profile runs right up to almost a 0 angle of attack. At 0 degrees angle of attack this blade has a decent amount of torque.  The 222 profile really gets interesting when you put a load on it and the angle goes up to 2 or 3 degrees. This is where the lift increases substantially.  Good luck you are doing a great job with this profile.   Dave Moller

DHD: PLEASE NO MORE SPAMMY COMMERCIAL LINKS ELSE YOUR POSTS WILL BE REMOVED

[ruddycrazy]

G'day Guy's,
                 It does seem the GEO222 profile is the preferred profile for wind genny blades and the link Kevbo put up where one can view different profiles quite easily some of the naca profiles are very similiar. On viewing them several times it does appear on the leading edge the difference in profiles is where the blade profile cross's the line. The naca-8514 cross's say at 3" on a 10" wide blade where the GEO222 cross's the line at 5" respectively. So in that regards how would the 2 compare for say a 4 metre blade set (16').

Cheers Bryan

[ChrisOlson]

DHD: PLEASE NO MORE SPAMMY COMMERCIAL LINKS ELSE YOUR POSTS WILL BE REMOVED

What's a spammy commercial link?  Dave Moller has been building GOE222 blades for guys on this forum for years.  I can point out numerous posts in the past where guys have asked what the link is to Royal Wind & Solar where these blades are built.
--
Chris

[DamonHD]

He dropped a link in the middle of a para apropos of nothing at all in the first post that I looked at, just like SPAMmers dropping in links to random 'cheap goods' and 'cheap meds' (etc) sites.  And each other post had a link too IIRC.

And as he only had 3 posts, and we have rules about not putting links in early posts, AND he had put in his site URL in his profile too, it seems pushy-->SPAMmy.

So let's please not argue about this: putting links in early posts before bona fides have been established for the user ID is not on.

Rgds

Damon

[ChrisOlson]

So let's please not argue about this: putting links in early posts before bona fides have been established for the user ID is not on.

Well, OK.  I just know Dave M has posted here before many, many times in the past.  The user ID he's got now is different than what he used to use so perhaps he forgot the login or password and made a new user account or something.  At any rate, he's far from a "newbie" on this forum and there have been many requests in the past for the link to his website for the Wincharger blades he carves.  So putting it in his user profile is probably a good idea, and not at all spammy or pushy to my way of thinking, simply because Dave M is a long time member of this forum under a different user ID and there are a lot of members of this board flying his blades, including DanB.
--
Chris

[kurt]

if you loose the password to your account there are methods available for recovering your account if the automated methods do not work there is an admin email address at the bottom of the main page you can use to contact a moderator for assistance if you insist on signing up for a new account then you can expect to follow all rules that apply to newbies until you get your post count back up because moderators apply newbie rules based on post count only it is not there job to try to figure out if you had an old account and abandoned it etc. just way to many members here to keep track of that stuff.

[ChrisOlson]

I build some modified GOE222's out of Douglas Fir 2 x 6's using the following hand tools - power planer to rough shape the blade, custom made draw knife to cut the face, belt sander to finish it, picnic table for a workbench, pine tree for shade, and Bud Lite to reduce the effects of the 90 degree weather:



This is actually for a four-blade rotor for an experimental 13 foot geared turbine that I'm building.  I have three blades finished, one to go.  The pitch is 9 degrees, and the chord is 5.55", for this four-blade setup.  I modified the GOE222 airfoil at the trailing edge to remove some of the "cup" on the face, which I think is partially responsible for making these blade refuse to back down when the machine is furled.



The following photo has a printed template of the GOE222 airfoil stapled over the end of the blade to show how I modified that trailing edge for less "cup"



My hope is that the modification will provide less drag and slightly less torque for the four-blade rotor, which will have plenty of torque anyway with four blades instead of three.

I'm just using these Douglas Fir blades for cores - they will be laid up with two layers of glass and carbon fiber.  Just using hand tools it takes me about 2-1/2 hours to build one blade.

I studied the GOE222 airfoil and compared it to flat-faced profiles like the NACA 4412 or Clark-Y and it's pretty much the same except for that trailing edge.  The trailing edge provides the effect of wing flaps on a Clark-Y - lots more lift, but also more drag.  My modified GOE222 has more of a concave face than the Clark-Y but no "wing flaps" in the breeze like the GOE222.  I'll report later on whether or not I get more power (kWh production) from the four-blade modified GOE222 setup vs the three-blade GOE222 on one of my geared machines.
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Chris

[Dave B]

As usual Chris, this is great work and we'll all be very interested to hear how itl works out with your profile. Being in the log home business as well as RE contractors often "cope" logs with a large table saw or hand saw blade running perpendicular to the work piece. Just taking off a very small amount each pass with a rip fence or jig works very well and could easily cut the concave face of his type of profile as well as the many other options previously mentioned. I'm sure your draw knife acts very much as a scraper with the blade of the tool having the curved profile. Not many have designed a machine for a particular profile like you have, seeing more of that kind of engineering for any profile could far exceed the "anything will work" performance most accepted by home brew machines.  Dave B.