here are a few drawings for making props from pvc pipes. just a few observations from my own experimenting. i think using any pipe less than 3 inch diamater may be a waste of time unless it is going to drive a very small genny. i also suggest that you practice on paper towel tubes to get the idea of doing it instead of wasting pipe.
the first drawing is of a simple one piece prop. i have not given any dimentions other than how to cut. you must decide in your own mind the size of pipe and length. i will however give my suggestions.
begin by drawing a line from one end to the other (blue line) A to B. often there is printing on the pipe that will give you a good guide. next, draw a line at centre around the diamator (C to D). the junction of these two lines will be your exact centre of blade and this is where you may drill your hole for mounting to hub of your choice. E, F, G, and H ( red line ) is what you will end up with after you cut out at the red lines. my perspective with the drawing is not the best, but you may refer to my last posting on pvc blades to see what they look like. the outer round surface of the blade will end up on the opposite side the wind is blowing from, and the inside of the pipe is what will face the wind. i can suggest that the tip width should be approx. 1/4 of the outside diamater of the pipe. if you have a 4 inch pipe, your tip width will be 1 inch. if you equal the tip marks at the end of line A to B, you will have 0 degree at the tip. moving the tip marks to the side of line A to B will give you some degree of angle. i prefer 0 degree.the straight edge of the blade is your trailing edge and should be cut some what to the side of line A to B.
The angled edge of the blade will be your leading edge and should not be cut more than 1/4 the way around the diamater of the pipe from line A to B. JUST A REAL GOOD TIP, to mark the angled edge of blade, use a length of that black metal banding strap they use to hold crates together with. have someone hold one end on the mark and the strap will follow the contour around the pipe to the other end of the mark. a metal measuring tape works good too turned upside down. i prefer a small fine tooth hand held saw to do the cutting. scraping the cuts after with a sharp blade will give you a good finish. this style of blade seems to give decent starting torque and runs very fast. SORRY FOR ALL THE LINES TO READ BUT THIS IS THE MAIN CONTENT OF THE INSTRUCTIONS AND AM TRYING TO COVER ALL POINTS. GO TO NEXT PICTURE.
here is what i call a high torque blade. it does not run as fast as the previous blade but seems to provide tremendous torque. a good choice for an alternator with many poles. again, this drawing is not the best, so refer to last posting to see what it looks like. the widest part of the blade has been moved from the middle to the position between middle and end of blade.
here is a method of cutting multiple blades from a shorter piece of pipe. just lay out the pattern and cut. DO NOT TAKE ONE CUT OUT BLADE AND USE IT TO TRACE OUT OTHER BLADES. this will result in blades becoming narrower. mark each blade seperately. these blades can then be mounted in any number that you need and to what ever hub style you may design.
i screwed up on showing the last blade design with a hub point. you will have to look at the next posting after this one if i can get it posted. it is an interesting one in that by laying the two seperate blades on the other, you can slide sideways either blade for fine adjustments for balancing. i think a lawnmower blade hub would be a good one for this assembly. hope it comes out on the next posting.
hope you can use these to your benefit and projects--zubbly |
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