I've slowly been putting together the 10' turbine according to the online plans as well as the book (which is identical as far as I can tell). I'm just about done with metalwork part 1 (
http://www.otherpower.com/metalwork.shtml). Before this, I had no experience at all with fabrication and had a limited array of tools. In a previous life, I was an auto mechanic and I'm also an Electrical Engineer so I didn't let the lack of experience hold me back. Because of the lack of experience, I had to learn and sort of "invent" processes of my own to get these parts made and thought I'd post to give others a sense of some techniques that can be used with a limited number of tools.
Here are the tools I ended up using to do the fabrication:
Cheap tabletop drill press with ~500 rpm minimum speed
1/2" variable speed spade handle drill (Dewalt DW130V)
Angle grinder
Circular saw with a metal cutting wheel (abrasive type) and wood blade
Jig saw with wood and metal cutting blades
Appropriate hole saws, bimetal
Hobart Handler 187 MIG welder
Misc C clamps
Lengths of 2x4
I had some of the tools already. But you could do this part of the project with only three power tools: the 1/2" variable speed drill, the circular saw and the welder. A handheld hacksaw and some handheld files could replace the jig saw and angle grinder (assuming you don't want or need to grind your welds which I'm, in fact, not bothering with). You could even rent all of these tools. Though if you are like me with relatively little experience, it won't be like you can crank out all the parts in a weekend. I could do that now, but the first time through is a lot of fiddling, trial and error, measuring and remeasuring (measure twice, cut once!).
Stator bracket:
Since I didn't have the bracket fabricated for me and I had no way to easily cut the complex shape, I opted to use 1/4 plate with 1/4 inch bar stock for the spokes welded to it at the right angles. One shortcut I took was instead of a round disc for the middle, I just cut it square. It doesn't look as pretty obviously, but shouldn't effect the operation of the turbine at all. I was going to try and cut a disc, but it is pretty hard to use a hole saw that big on 1/4 plate with a hand held 1/2 drill. Cutting the plate with a circular saw, though, is a piece of cake.
To drill the 1 1/4" hole for the spindle, I used a hole saw. Now, drilling with a hand held 1/2 drill is tough at first because the hole saw wants to skip around on the metal and not really get on track even with the pilot bit. I got around this by first drilling through a 2x4 with the hole saw. Then, I put the plate on a suitable support on the ground and lay the 2 x 4 with the hole on it in the appropriate spot. I stand on the 2x4 and then drill down (with the 1/2" drill) with the hole saw through the plate. The hole in the 2x4 keeps the hole saw aligned pretty well and I'm able to start a decent groove into the metal. After I get a groove, I put the thing on the drill press and finish the hole with that even though the rpm is actually well above what is recommended. I take it slow and use lots of oil which helps cutting tremendously. For other disc parts, I do the same basic procedure. For drilling the hole in the 3" and coping the 2", I do that entirely on the ground since I have no way to clamp the thing into the drill press very well. Drilling the hole and coping take much less time and effort than drilling a disc out of flat plate (since the hole saw is in contact with a much smaller piece of metal at any given time), so no big deal.
Rear spindle support:
The only thing different for me for this part is that the plans say to use a 3" hole saw. That makes a 3 inch hole in the plate, but the disc ends up being 2.75 inches around which is a pretty big gap to fill with the welder (1/8" gap all around). It may be the lack of precision with my drilling method since I am limited in precision with the hand drill and the table top drill press has visually noticeable runout. At any rate, I made the disc with a 3.25" hole saw and it fits in the 3" pipe perfectly with only a very small gap (maybe 1mm or less).
2" alternator/yaw bearing connector:
For this, I just clamped the pipe into the same jig I use to cut pipes (see more below) and then put 2x4 with a 2.5 inch hole cut in it above one end of the pipe to guide the hole saw. The only thing to be aware of is that you can't cut all the way through the pipe in one go since the hole saw is more shallow than the width of the pipe and it bottoms out and rides on the pipe preventing further cutting. Sounds obvious, but I screwed around for nearly 15 minutes wondering why I couldn't get it to cut before I realized this. So, I cut the top part of the pipe off with the jig saw and was able to get through the rest in like 2 minutes.... Silly, but frustrating, little mistake.
Pipe cutting:
To cut the pipe, I have just used the circular saw with an abrasive cutting wheel. I clamp the pipe into a 2x4 jig I made to get an edge square to the pipe to run the saw along. The pipe itself lends squareness along the other axis. Even though it took three turns of the 3" pipe to cut through it with this method, amazingly it is flat and square with only a very minimal amount of grinding cleanup required.
Last thought: Man of man would I like to have a plasma cutter....
