Bridges To The Future: Finishing the blades

With the blades all carved out it was time to weigh them. Two of the blades weighted in at about 7 pounds each. The third one was 7.4 lb. This will be dealt with later in the process.

Knots were going to be a problem as one or two of them already came loose during the carving. My solution for this was to drill a hole at the edge of each knot and then put in a stainless steel screw. The threads will cut into the knot and the blades material holding the knot in place.

Using a hand hacksaw I cut off the head of each screw and any part that was sticking out the other side of the blade. Then each screw stub was ground flush to the blade surface.

Now it was time to drill the mounting holes in each blade. This was complicated as the blades not only had to fit the mounting plate of the hub still up on the wind turbine the 3 nose cone mounting holes had to line up and fit. Tricky at best.

The back story. The used Enertech was a $300 "boat anchor" when I got it 25 years ago. The windings on the generator were toast and the blade mounting plate had a crack in it. At the time I was working on another renewable energy wind project and wanted to get a wind anemometer for the Scales Mound school where I was teaching. An article in Home Power magazine on a Wind Explorer data logger made by NRG systems caught my eye. I decided to reach out and contacted NRG systems to see if they could help. To my pleasant surprise the president of NRG, Dave Blittersdorf emailed me he would be happy to send a Wind Explorer unit to me free of charge. I was thrilled. I told him about my Enertech rebuild project and the problems I was having because Enertech had gone out of business. Dave told me not to worry, he could help because he had bought out the inventory of Enertech when they closed. He had a mounting plate and would send it to me for $25.

So what to do with the old blade mounting plate? For years it "slept" in my iron pile.

Then one day I needed a base for one of my metal yard art sculptures. As the plate was welded on I thought I could take some measurements and make what I needed out of a piece of plywood. Well I tried that and have another story to tell about measuring angled pieces like this.

Anyway after scrapping out the plywood I took another path. This would prove to be a much better solution and more accurate. 30 minutes later, wala I had my plate with blade mounting holes to use as a guide.

Each blade on the Enertech has a plate like this so I used it to locate the four holes. The angle iron piece at the bottom edge has the nut welded into it for the nose cone mounting screw.