New copper cable size and length recommendations Summer
|Additional information for tail vane
(table on page 27)
Tail hinge angle for the largest machines is only 15 degrees for battery charging,
increased to 20 degrees for Grid-connected versions. The 3600 tail vane thickness is increased to 9 mm. Target weights are given for the plywood vanes.
|Stator mounting plate for the 1200 or four
The stator mounting plate is drilled in 3 places to support the studs that are embedded in the stator casting. Normally I always make this plate triangular, but out of laziness I showed a square plate in the CAD renderings in the Recipe Books.
However I met Davide Bozza in Belgium who showed me his turbine, made with the square plate, which was very close to the stator, and he was suffering some cogging due to magnets interacting with the stator mount plate.
I have therefore updated the Recipe book drawings as shown on the right to show a triangular plate of minimum dimensions such as to minimise cogging and iron losses.
|Page 36 in One table of some of the
2009 inches edition I wrongly stated that the numbers of
coils in the stators.
Nobody ever pointed it out to me at the time, but I fixed it accidentally in the August 2010 edition when I put both magnet and coil numbers in the table on page 36 (see right)>>>
I learned of this from reading the Fieldlines discussion board!
Anyway, if you are using the early Inches edition before August 2010 then please look at this table on the right. In any case you can find the correct number of coils in various other places in the book but this doesn't excuse my error, sorry.
|Page 29 of the Inches edition (Why
did nobody point this out to me before?)
There is a mistake in the table at the bottom left hand corner of the page describing the 12-foot turbine.
The length L needs to be 15 inches. Otherwise you will not be able to achieve the desired shape of frame and get the desired 8 inch offset.
I am sorry for this and previous mistakes in the Inches edition and had sincerely believed that I had rooted them all out. I have not built a 12 foot machine in inches for some years, which is the only rather poor excuse I can offer. Personally I prefer to work in metric since my brain is only small. Fractions of inches send it spinning.
Another test is to connect the rectifier and check the DC output voltage to find the ‘cut-in’ rpm. If the cut-in rpm is much lower, then you should increase the gap between magnet rotors to reduce voltage and prevent the turbine from stalling.
12-volt turbines can usually cut in at the slightly lower rpm without fear of stalling because the wiring in 12-volt systems is more inclined to create a voltage drop that pushes up the rpm and prevents stalling later.
If you are working with 8 or 16 magnets then you can skip the 60 degree stage of the process, and just use this angle-halving technique to keep on dividing angles in two until you have the correct number of divisions. Start with Y and Z and find 90 degrees then go to 45 (for 8 magnets) and further halving them again for 16 magnets.
To divide angles in half, just use trial and error and find where the two circles meet.
(To find 40 degrees (1/9th of a circle) you first find 120 degrees (1/3rd) and then divide this in three using trial and error to get the right setting for your compasses. This would be for finding the best size for a coil in a 9 coil stator.)
diagram of a larger stator mould for a 3600 or 4200 turbines
Start by drawing diagonal lines across the corners to find the centre. With the 16 pole machines you could also use these lines to mark the four mounting points. But in all cases do check that they are equally spaced apart.
A new table to help clarify the numbers in each turbine:
|Page 37 new diagram of
larger stator connected in series/star for voltages above
With 12 coils then the phases are (1,4,7 and 10) (2, 5, 8 and 11) (3, 6, 9 ,12).
Connections between most of the coils are very simple: connect the finish to the start of the third coil on (skipping two). Bypass two coils and connect to the third one. Often a good position for the actual solder join is between the two coils you are bypassing. See the section on tools for advice about soldering.
The diagrams show the wires spread out, but in reality they need to form a neat bundle that lies snugly against the outside of the coils.
You will also need to make a spacer that keeps the two cheek pieces the correct distance apart, 12 mm (10 mm for the 1200 turbine). The best approach is to drill the hole pattern in a piece of plywood, using the first cheek piece as a pattern, and then cut between the centres of the corner holes to create the spacer piece. You can adjust the thickness if the first coil attempt does not fit the stator. A thicker spacer makes a narrower coil.
When the first coil has been wound you should check its size to make sure that it will fit into the stator. For example if there are 12 coils they must fit within a 30 degree segment (9 coils each fit within 40 degrees, 6 coils each fit 60 degrees). Draw out the shape on paper or plywood. Lay the coil in its place so that the outer edge of the hole matches the outer edge of the magnet disk. If it looks fine, then carry on and wind more coils. You can also find out the ideal size for the island at this stage (see page 40).
“Two in hand”
Where the table specifies “[email protected]” wire you will need to put the wire on two reels and feed two wires into the winder side by side. Connect these wires in parallel.
Where there are two wires ‘in hand’ (e.g. [email protected]) they are connected in two parallel connections as shown here. I prefer to keep the two connections apart to reduce parasitic current pathways.
Welding the yaw bearing to the alternator frame of the larger turbines 3600 and 4200
See also the video
Mark the position of the centre of the alternator on the underside of the flat-bar.
Subtract half of the pipe diameter to get 156 or 206 mm offset.
Incline the frame at 4 degrees to the bench and then hold the yaw bearing level while tacking it in position.
The hinge is not fixed to the downwind (back) side of the yaw bearing, but about mid-way between the back and the side. (55 degrees off downwind.)
A good way to set it up for welding is to prop the frame of the machine up on the bench or the floor at 55 degrees to the horizontal. Then weld the tail hinge pipe on in a vertical plane above the yaw bearing pipe, judging this by eye if you like.
The axis of one pipe is directly above the axis of the other one.
|On the right is a photo of a golf rear hub
having the brake drum removed. Use a 115mm cutting
Below is a table of sizes for common hubs on vans.
I am becoming aware that I have not made the magnet orientations sufficiently clear in the plans. It should be possible to see the way it works in the drawings on pages 63-64 at the back. But for the avoidance of doubt as they say please look at the photo on the right showing which way around the magnets and coils are to be laid out.
My reason for going to a different layout in the 8-pole alternators is to provide space in the middle of the alternator for rotating parts.
|Page 43 of the Inches edition the magnet
jig design table of dimensions used to have 2" instead
of 1/2" for the radius on the large machines. I don't
know how I made that mistake.
These circles are of course 1/2" radius, to make a 1" diameter circle on the larger machines because the magnets radiate outward as shown in all the diagrams, for example lower down on the same page.
|Page 58 of both editions of the Book has a
paragraph entitled Magnet Spacing
I did not make it clear that the ratio of coils to magnets is also important.
For 3-phase output you have to keep a ratio of 3 coils to 4 magnets. If in doubt about changing the design, send me an email and I can check that what you are doing will work.
|Page 18 of the Inches version of the Recipe
This is a bad one. I find fractions of inches pretty confusing, which is why I prefer to use mm. But there is no excuse for the mistakes that I made in the table of thicknesses for the inches version. I am losing a bit of sleep over these because they do critically weaken the blades. The table on the right gives the correct thicknesses. Please be sure to use these thicknesses and not the ones in the book! Sorry!
The metric version is fine. I just made a bad job of converting the thicknesses into inches.
|Stupid mistake corrected in the table of coil
on page 36 for the inches version
There are 80 turns and not 8 turns for the 12-volt version of the four footer turbine.
COIL WINDER - I have gone back to my old type of coil winder (upgraded) where you can tape the coils before you remove them from the winder. Metric and English versions
Here is a video showing the coil winder in use (among other things). Actually the drive shaft in the video is slightly different, and Alan has a counter on his winder too, but the notches for the PVC tape are there, and you can see how to slip the tape under the leg of the coil and bind the coil tightly before it gets removed from the winder. First fold the end of the tape over on itself sideways to make it narrow so that it will slip in under the coil leg.
I always used to do it like this in years gone by, but for a year or so I have experimented with a different system. Overall I find that taping the coils before they come out of the winder is better. It makes sure they do not lose their shape at all.
Extra descriptions of the jacking screws used for assembly and disassembly of the alternator:
Drill and tap one of the disks in three places so that you can use jacking screws. The holes need to be a little smaller than the threaded size. See page 13 for guidance. Keep the tap perpendicular to the plate while you make the thread.
The jacking screws need to be clear of the other studs and the resin casting. You can make them up by cutting lengths of threaded rod and welding a nut on the end of each. Make them long enough to stand out beyond the ends of the mounting studs so you can easily get at these welded nuts. I use a socket spanner in a cordless drill to spin the screws in and out.
Page 31 where the angle of the tail hinge is set upPlease note that the 4200 machine can produce 2000 watts in grid connected mode with a 20 degree angle, but for battery charging it is better to use an angle of 15 degrees from the vertical. This can be achieved by cutting the cross piece down to 22 mm thickness and welding it on at 85 mm from the bottom of the hinge.
Minor text changes
Big changes with graphics
Page 29 should include the following sentence:“The exact length of the 89mm yaw pipe is not critical, but I recommend about 400-500 mm length.”
Page 31 first paragraph should read as follows:“Weld the inner pipe of the hinge (E) onto the yaw pipe securely because it has been a common weak point, especially with beginners’ welding and when the blades are out of balance and the tail starts to bounce about. Start by welding a cross piece of 30-mm flat bar to the inner pipe of the hinge, positioned 85 mm from the end so as to give the desired 20 degree tilt.”
NOTE THE WORDS IN BOLD
Page 63 dimensions of blade wood - thickness is slightly incorrect - here is the corrected version to match the table earlier in the text:
Sizes are in mm 1200 1800 2400 3000 3600 4200
thickness 35 35 40 45 60 75
|See pdf file recipe update august.pdf
which has four pages 26,42,43 and 46 ready to print.
See also "extrarecipe64and65.pdf" for some extra drawings for the back of the book
New graphicspage 26 welding setup diagram added
page 42 radius labels have changed
page 46 new pictures of the magnet rotors of the smaller turbines