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Forum Index : Windmills : MacGyver Ax-Fx Build
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Crew As promised, I have begun building my axial-flux wind jenny (generator) and will post pictures and commentary as I proceed. For starters, this project has taken me a long time to start simply because I want to make it so simple, you'd have to pay someone to help you screw it up. I'm trying to be innovative while at the same time use off-the-shelf materials, keeping the build within the reach of most folks. The only tool that you'll need and likely not have is a lathe, but we'll cross that bridge when we come to it. For now, here are the basics: I want to build an all-aluminum chassis. The reason is: extruded aluminum tubing (both round and square) is readily available worldwide. Second, it's strong and lightweight. Best of all, I've come up with a way to weld the stuff without having to use heli-arc! The "welds" are extremely strong and it takes only a little practice to get good at the welding technique. More on that later. Let's jump into it: 
This shows the basic all-aluminum chassis. I've used both square and round T-6 extruded aluminum. The base will be welded (later on) to another round aluminum plate, which will cary it on the mast or tower and act as a pivot, enabling the machine to turn into the wind via a flat tail. The tail as well as the blades will be constructed out of 2mm "Corflute" extruded plastic sign material. More on that when my shipment of Corflute arrives (next week???) 
My digital camera does not like tight shots. I apologize for the blurriness, but I wanted to show how nicely the round tubing welds to the flat tubing. This round piece will hold the windmill's main shaft; blades on one end and rotating magnet wheels on the other. 
Here's another angle showing those welds. These are basically "butt" welds. I'll explain more about the welding technique just a little farther down this page. 
I'm showing this shot to let everyone see that the welding technique does not distort the aluminum tubing on the inside of the weld. This tubing, by the way, is 1/16" thick. That's really, really thin stuff to try and weld without burning the crap out of it. More later. 
Here's another view of the entire chassis facing the opposite way. For now, you'll have to visualize with me: The three Corflute blades will be mounted on a hub to allow balancing and easy installation and removal. They will face into the wind. Behind that will be the main bearing, which in this case will be a "bushing". This entire chassis is only about 12-inches long, mind you -- yup, it's just a little fellow. You can make yours any size you want, but I like small stuff. There will be stops on the main shaft each side of the bushing, keeping its fore and aft travel to within less than 1/1000th of an inch. That's what we call a "running fit". It's not tight enough to bind, but won't wander either. Behind that will be a pair of wheels housing several neo-magnets in a circle around the wheels. These will be arranged in a N-S-N pattern and will each barely glide over the surface of a set of copper coils (called the stator) which will be locked to the chassis between the two rotating magnet-carrying wheels. On the rear end of the thing will be a Corflute vertical stabilizer, much the same as seen on the tail of an airplane. It will have a small controlling surface (rudder if you will) to allow me to compensate how far into the wind the thing points, so I can offset the action of the angular momentum created by the spinning mass. I'll cover all that when the time comes. Okay, I know it's on everyone's mind, so here's the Big Question: How do you weld aluminum without a $3,000.00 heli-arc set-up? This is so cool, you're gonna wet your britches! Here's a Link to the Website where I learned the answer for myself. Look it over and watch the video(s). I ordered their 1-pound package (approximately 22 welding rods) and got it in about 4 days through the US Postal Service. Total out-of-pocket expense was $45. It took only half a rod to weld that chassis and I think after a little practice, I could do it with less rod. Solar Crew: Hey! Do you guys know what this means to us all? It means we can now build All-Aluminum flat-plate solar collectors for heating water and other things (I heat oil, but don't try this without some instruction from me -- PM me). Aluminum is over the top compared to copper in its ability to transfer heat. Another thing is, although I used virgin aluminum for my windmill chassis, recycled stuff works just as well. The only difference is you have to spend more time cleaning the base metal before you fire up the torch and make the welds. I don't know how well this is going to work with folks popping in with comments, but my guess is when it's all done, I'll throw up a Web page of my own and drop a link here on the 4m (with Glen's permission, of course). For now, let's roll with what we've got! I'll add more as it happens, so stay tuned. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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Perry Senior Member  Joined: 19/11/2009 Location: Posts: 190 |
Hey Mac, Looks good. Anxious to see this thing after hearing about it for so long. I think it will definitely be unique. Interesting aluminum welding rods.I just use aluminum wire in my mig. Technically you should use a different gas but I don't and have had really good results with C25. Never really sick welded before. You seem to have a good technique down. I guess we'll just agree to disagree on the bushing vs. bearing issue. It's a pretty small turbine so maybe you'll be alright. Perry |
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| Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
We'll I just watched that video and I see it is not a stick welding process now. Basically it looks like a 'solder type' alloy that just melts onto the surface. There is no penetration into the part. I would be careful with butt welds. The load in your joint is going to be carried only by the thickness of your coating. I am not sure of the mechanism that holds it to the base metal though as there is no penetration or alloying going on there. Perry |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Perry You're absolutely right about weld penetration, but the up side to that is it doesn't distort the material (due to the lower heat range) and any over-the-top stresses could be bolstered using other means like clamps or straps. The rods came with a little "Facts" sheet and here are some of those: Tensile Str, lbs/ sq in = 47,000 Compression Str, psi = 60,000 - 70,000 Shear Str, psi = 34,000 Charpy Impact Str, psi = 4 ft-lb to break 1/4" bar Hardness (Brinell) - 100 Ductility = Good Melting Pt. (deg. F) = 732 Specific Gravity = 6.7 Density (lbs / cu in ) = 0.25 Coefficient of Linear Expansion = 15.4 x 10^-6/*F Electrical Conductivity = 24.9 % of Copper Thermal Conductivity = 0.24 Cal/cu cm/*C I didn't try to break my new toy, but it "feels" pretty tough. Since this is such a small build, I think it should hold up under heavy winds. I plan on making the blades only 18" - 24" (haven't decided yet). A larger machine could use "gusset" welds as well as some straps and bolts if necessary. The welds just make it look cooler, IMO. 
Oh, while I'm here: I plan on making a couple windmills on this build. One is the ax-fx of course, but the other one(s) will be a neo-impregnated, iron-core fart fan a.c. motor, which will be spun up using a belt transmission. My hopes is it will be an easier build for folks who just want to build something to charge a battery or two [ like me :O) ]. Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
Perry; You are correct about the method of welding with this alloy stick rod. The procedure is Identical to Oxy-Acetylene Torch welding. I happened upon the introduction of this new technology while attending a Fly in of experimental aircraft. This was about 6 years ago at Arlington Washington. The vendor cut and welded a Coca-Cola can, also welded Brass and Aluminum together. and several other combination's of metals. I purchased the Torch with 2 packages of rods.and a bottle of Mapps Gas. The Vendor showed photo's of an Aircraft engine with a broken Cylinder Head, the repair was shown in steps from weld to grinding and polishing. The beauty of this is that the metal need not reach the melt temperature to bond. It compares to the strength of the metal and does have the ability to stand up to temperatures above 600 F. A standard Propane Torch can be used to weld,But Mapps Gas should be used because propane is a little bit cool for a quick fluid weld. This is good Kit to have around. EDIT, You Guys Type much faster than I There were no Posts after Perry's 1st. Time has proven that I am blind to the Obvious, some of the above may be True? |
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oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
Yes the welding is interesting , more importantly, the project is afoot. Keen to see this morph into a windmill from the bare bones shown so far. I will be a hard sell for the iron core neo version on a belt with such little blades...... but I've been amazed by you before too 
Keep it coming.... and that damn avatar is making this diet I'm on less appealing each time I see it..... ..........oztules Village idiot...or... just another hack out of his depth |
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| Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
I guess this isn't really welding at all. At least by the definition of welding. It's more of a solder process. It's more of a convenience or marketing term because people associate metal joining with welding. The 'material specs' that Mac posted are impressive. I think it is a pretty strong material. My only issue is with how well it bonds to the base material. Wood glues like we use to glue our blade blanks together is quite strong. The joints are also strong because the glue 'penetrates' into the wood. If you try gluing two pieces of metal together you get no penetration and a very weak joint. My point being.....If you have failures in your joint maybe you could add some geometry to the joint, like roughening up the surface or drilling multiple holes for the metal to flow into (simulating wood grain for wood glue)that could help the joint strength considerably. Perry |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Hi Mac,( or is it Mr. Spam)(Ok i wont call you spamy if you dont call me winky) I thought this day would never come, where we get to see the build. It is kinder sad that growen men here, are getting excited about 3 bits of shiny metal welded together.
Can i give a pointer on the close up camera shots. Read the manual..... Most digital cameras default to "landscape mode" and are great for distance shots. For things closer you will need to change the setting to portrate. Mine is a cheap crappy old one now, and the 2 settings are marked with a little mountain symbol for landscape and a flower symbol for portrate, yours will have some choice of settings too. It would be well advised to have a fiddle and work it out, so us poor old buggers can stop polishing our glasses to see the images better. 
Pete. Sometimes it just works |
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GreenD88 Senior Member Joined: 19/05/2009 Location: United StatesPosts: 104 |
Heli-Arc is still the best way for a strong structural/pressure weld. But other techniques have been around for a long time, they even sell rods for old arc welders, which would probably give a better penetration. Here's a company that sells the arc welder rods. http://www.zena.net/htdocs/welders/Rods/Aluminum.shtml Also most welding places sell aluminum brazing rods too. But if all you have is a mapp torch then those soldering rods are probably best for you. If it was me before putting too much effort into it I would make up a test piece and load test it with a bunch of concrete blocks and see what the breaking point is. Then make sure that the force exerted by the blades in the strongest gale isn't going to rip it apart. I have doubts that the low temp solder will bond strong enough. But then again aluminum is fairly absorbent metal. If you need some help with finding formulas, I'm sure someone here will help. Anyways it's looking good. Keep us updated. Edit: Found a couple links to durafix on ebay. 1lb for 23.99+shipping and 1/4lb 6.99+shipping. 1lb Durafix And only use a stainless steel brush when cleaning. 1/4lb Durafix Licensed Master Plumber / EPA 608 Universal License / 410a Safety Certified / Medical Gas Brazer/Installer |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
[Quote=Pete]Can i give a pointer on the close up camera shots. Read the manual..... Boys don't read directions! Heck, I'm pretty sure I threw the manual away as soon as I got the thing. Thanks for the pointer, though. I'll fiddle around with it and if I get a better picture, I'll post it here for you. In the meantime, just think of my blurry pictures as naked women instead of windmills and use your imagination! Perry Remember, this thing is only about a foot long, so I imagine if I blasted it with my 20-gauge pump, it'd still survive. I took the "welded" chassis to my nephew's work (he's a certified welder) and he tugged on it harder than I would have liked, but it didn't budge. I think it's pretty strong despite my agreeing with everyone's point of view that it is merely metal-hot-glued together. I plan on installing a moveable "rudder" on the test model and controlling it using R/C. I'll fly the thing in a very strong breeze and furl it hard left and hard right several times to test the worthiness of the build. I'll try to capture that on video and throw it up on You-Tube for everyone to watch. Heck, as well as this stuff works so far, I'm thinking about designing and building a bullet-proof (literally!) R/C glider fuselage out aluminum. Talk about the ultimate bolt-on-wing arrangement! Boy . . . even more projects to think about! . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Cudos To Pete Okay, I took Pete's advice and messed around with my camera until I found that little flower and guess what? It worked: 
Here's a clear tight shot of that round-to-square butt joint. 
Here it is again from a different angle. 
This is that flat-seam butt weld. 
And lastly, this shows the 45-degree butt-welded joint where the frame members join. This is the joint my nephew tugged on so hard, I thought I'd faint! Thanks for the advice, Pete. (You know, Spamy & Winky aren't all that bad!)  Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| neil0mac Senior Member Joined: 26/12/2009 Location: AustraliaPosts: 210 |
For those who think the joints need 'beefing up', there's always a gusset that can be added - even if only for a bit of (visual) re-assurance. |
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| Robb Senior Member Joined: 01/08/2007 Location: AustraliaPosts: 221 |
Now your talking! |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
GreenD88 Hey! Thanks for that Durafix link. That's a great price. I paid a total of $45 for the pound I got including shipping, but your link is a little cheaper. I've had several poor experiences buying stuff on eBay before, so for me at least, I'm satisfied with what I've come up with. One thing's for sure: The stuff works well! . . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| GreenD88 Senior Member Joined: 19/05/2009 Location: United StatesPosts: 104 |
I've been buying stuff on ebay for over a year and haven't had a single problem probably have spent over $300 so far. But I don't usually bid on an auction though just usually do "Buy it Now" stuff. Can find a lot of stuff cheap, I especially like the Daily Deals get some good stuff on there sometimes. Licensed Master Plumber / EPA 608 Universal License / 410a Safety Certified / Medical Gas Brazer/Installer |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
May 19, 2010 Update Okay; here we go: 
Just to keep things in perspective, this is my lathe and it's run by that 12-volt garden tractor battery sitting to the rear. The reason for all this "smallness" is I plan on retiring in my travel trailer when the time comes (soon!). 
Here's the back end of a HDPE (high-density polyethylene) plug I am using as a bushing to hold the windmill's shaft. The hole was cut with a letter "O" drill; the shaft is 5/16" steel. This gives a good running fit. 
Here's the same shot from a different angle. 
I cut the bushing with an "interference" fit and jammed it into the aluminum tubing. There is a tiny shoulder cut on the front to keep it from traveling under load. 
This is the FRONT of the windmill's main bearing (bushing). You'll likely note I "faced" the rear and not so in the front. This is so I can test the wearability of the rough HDPE against a thrust bearing. If it smoothes out from wear, I'll just face it off next time. It is just an experiment. Next up will be the main shaft and the hub, which will cary the three Corflute blades (still waiting on the Corflute shipment!). Stay tuned! . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Much better Spamy. I can see clearly now.......................(theres a song in there) Im sure there is a bit of old hippy in you somewhere, so just remember "flower power" 
Although i did like the naked girls in the early photos but they fogged my glasses up.
Pete. Sometimes it just works |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
May 20, 2010 Update: I'm back at it: 
For the time being, I've cannibalized a former build just to use the parts and not have to make more. This is the basic shaft, with thrust washer (front) and stop (rear). The shaft is 5/16" steel and I ran it into the bushing using light machine oil and a high-speed drill. Spins like a top! In the picture it looks crooked to me too, but it's not. 
Some of you will no doubt recognize this end of things. It is from a former, somewhat less-than-successful build (Oz snickers!). The plan is to remove the wheel containing the neo magnets and replace it with the blade hub, which will be turned in the next few days. Still awaiting Corflute shipment! 
Here's the tail end. I used a 10-24 set screw to anchor the stop to the shaft. I will turn two more plate-hubs similar to the one on the front end; each will hold one set of opposing neo magnets on either side of the stator. Stay tuned! Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
Hey Mac, I just noticed in the first pic of your last post that your rotor is inclined about 3 degrees, presumable to prevent a tower strike. Come clean, was that planned or a mis-alignment during fab? Am I the only one that has welded something crooked but had it actually end up helping in the end? Perry |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Perry Nope; it's actually straight. When I snapped the picture, the angle of the lens made it look crooked. I measured everything as I built it and afterwards as well, so I know it's straight. I put a little disclaimer to that effect in the picture caption, by the way! Edit: I think I figured out why it looks crooked: The wheel holding the magnets has lifted the whole shebang off the table a bit and I took the shot straight down from above. This would put the shaft portion of things on a bit of a tilt, thus the illusion that it's crooked. Sounds good to me!
Even if it were a little crooked, the way this thing is going to be built, it wouldn't matter. The critical part is that each magnet array runs parallel to the other and to the stator. If that turns out to be on a bit of an angle, no worries. As far as the blades striking the tower, I don't think that will happen (I suppose everyone says that though, eh?) because I'm using symmetrical-section blades and a positive pitch of between 15 and 25 degrees (I think). Until I actually jam things together, I won't know the final pitch, but when I figure it out, I'll post it. The only tower strike I've ever experienced was using aluminum Clark-Y blades, which had positive lift. That was a doosey of a strike, by the way! 
. . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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