Smokeman Posted January 18, 2009 Share Posted January 18, 2009 I need to make a sheet metal cone to put on top of a large bird feeder. I do not know how to make the cone. The cone is 19" round at the bottom and the top is to a point. The height of the cone is 12" top to bottom. Thanks for any help. Quote Link to comment Share on other sites More sharing options...
littlewolfsmithy Posted January 18, 2009 Share Posted January 18, 2009 Im thinking if you make a template out of paper like a dunce cap of years gone by, it will give you a good idea of size and shape of the steel.http://homepage.mac.com/dfleary/.Public/ConeTemplate.pdf Quote Link to comment Share on other sites More sharing options...
irnsrgn Posted January 18, 2009 Share Posted January 18, 2009 (edited) This is a copy of a Blueprint I did for IFI TO LAY OUT A CONE by irnsrgn cone 01 - Start by drawing a center line and then draw the cone on the center line full size as shown. cone 02 - Next using a compass or other means, draw in the hemisphere under the line BC as shown, what this does is give you a half view looking at the bottom of the cone. cone 03 - Next using a compass, divide the hemisphere into 6 or more equal spaces as shown. On a large cone you will need more divisions, as this is the means you use to get the outside diameter of the bottom of the cone. cone 04 - Now draw line AB as shown and using a compass or other means, draw an arc from B with A as the center point as shown. cone 05 -Now using a compass or other means, lay out the divisions as shown and number them as shown to avoid mistakes. Then draw in line AC and you are ready to cut out and form the piece into a cone. If you were accurate in your drawing and transfering of measurements you should have a cone that has a tolerance of + or - the thickness of the material. If the cone is going to be a large one and needs to be bent on an apron or press brake, draw lines from all the segment marks to point A as reference lines for braking the material. I have made cones for different things up to 15 foot in diameter at the bottom out of 3/16 plate for oil well tank tops using almost this same method. I hope this helps you understand how to make a cone. Edited January 18, 2009 by irnsrgn Quote Link to comment Share on other sites More sharing options...
Smokeman Posted January 19, 2009 Author Share Posted January 19, 2009 Thanks for the information guys. I will try both and see how I make out. Thanks Again ! Quote Link to comment Share on other sites More sharing options...
irnsrgn Posted January 19, 2009 Share Posted January 19, 2009 When making hats (tops) for oil field gun barrels and storage tanks, I used math to lay out the cone tops, radius and height to find the sloping length, (hypotenuse) then found the circumfrence with that measurement, diameter of tank to find the circumfrence of tank, Lay the sheets usually 3/16 thick out and weld them together, then use my trammel points to layout a circle using the radius from the hypotenuse measurement and then cut it out and making sure I had an unwelded edge to the center of the circle. Raise one side so I could place a large wooden block under the exact center, then subtract the tank circumfrence from the hypotenuse circumfrence and measure off the distance half way either side of the unwelded edges to the center. tack weld on a couple of pad eyes, use a small comealong to pull one edge to the mark on the other side, clamp the edge and start moving up the lap edge tacking as I went, then after everything is stable, weld the seam and hold up to the tank end (tank laying on its side) with winch and poles on truck and using a ladder start tacking the edge of the hat to the tank top. Usuaally by myself, not hard if you plan what you are gonna do. Quote Link to comment Share on other sites More sharing options...
Jack Evers Posted January 27, 2009 Share Posted January 27, 2009 Let me take a stab at it. Irnsrgn is starting with the height of the cone and the diameter at the bottom. Smokeman has listed the height and apparently the circumference at the bottom (19 inches round?) although I'm not sure. If I'm correct, Smokeman's cone is about 6 inches in diameter. 19/Pi (3.1416) equals 6.05 inches. In step 3 the horizontal bottom line should be the 6.05 inches (or the actual diam of the bottom of the cone). The vertical line is 12 inches and the AB line is the actual sloping length (square root of 12 squared plus 3.025 squared equals 12.4 inches.)The half circle is then equal to one half of the 19 inch circumference or 8.5 inches. By breaking it into six short tangents, they can be measured and transferred twice to the curve in figure 4 as 1,2,3,4,5,6,7,6,5,4,3,2,1. The result is the template minus any overlap if you plan to overlap and rivet rather than weld. That should be the original 19 inchs. If on the other hand the diameter of the cone is 19 inches ( a more realistic slope and dimension for a bird feeder). The side distance would be 14.7 inches and the length of the arc in fig 4 would be 59.7 inches or about five feet. Quote Link to comment Share on other sites More sharing options...
irnsrgn Posted January 27, 2009 Share Posted January 27, 2009 (edited) On a seperate piece of paper. The first 3 drawing are on one piece, the last two are usually on the piece you are actually going to use and cut out. Edited January 27, 2009 by irnsrgn Quote Link to comment Share on other sites More sharing options...
irnsrgn Posted January 27, 2009 Share Posted January 27, 2009 evidently one or more posts got deleted in the update/meltdown. Quote Link to comment Share on other sites More sharing options...
Smokeman Posted January 27, 2009 Author Share Posted January 27, 2009 Thanks guys, yes, the post got deleted somehow during the down time. I am not sure how to do the steps after I divided the hemisphere into equal parts. As far as the cone size, 19" diameter on the bottom. Point at the top. The distance from top to bottom, 12". It should be easy, I know you have it there,but I just dont see it yet. Thanks for your help. Quote Link to comment Share on other sites More sharing options...
Grant Posted January 27, 2009 Share Posted January 27, 2009 (edited) Smokeman, The line A-B in step 4 is the same line A-B you determined in step 1. Then with a compass draw an arc the length of A-B and divide it to equal twice the arc length B-C. This gives you your A-C line If you look at steps 2 and 3 (pictures of the cross section) as if the arc came vertically out of the page, and not like an upside down ice cream cone. You will see why arc length B-C is 1/2 of the arc length you want. -grant Edited January 28, 2009 by Grant Quote Link to comment Share on other sites More sharing options...
Smokeman Posted January 27, 2009 Author Share Posted January 27, 2009 Thanks guys, I think I have it now. Quote Link to comment Share on other sites More sharing options...
Grant Posted January 27, 2009 Share Posted January 27, 2009 Smokeman, congratulations on your promotion to senior member. -grant Quote Link to comment Share on other sites More sharing options...
David Einhorn Posted January 28, 2009 Share Posted January 28, 2009 Try this. Take a sheet of posterboard and roll it into a cone at one corner. Adjust the tightness of the cone until it matches what you want, cut off the excess paper, unroll and use the posterboard that you formed as your template. Quote Link to comment Share on other sites More sharing options...
Smokeman Posted January 30, 2009 Author Share Posted January 30, 2009 Hey Guys, I made a pattern out of poster board from the formulas that you shared and helped explain. Sorry it took so long for me to figure it out. It Worked out perfect. I will post the bird feeder on this thread when I finish it up and have it powder coated. Thanks Again ! Just shows, never too old to learn how to do something new. Quote Link to comment Share on other sites More sharing options...
irnsrgn Posted January 30, 2009 Share Posted January 30, 2009 (edited) might interest you to know, that the formula (procedure) I gave you is from the 1800's. procedures from that early a period are uncomplicated and much easier than modern ways of doing things. Edited January 30, 2009 by irnsrgn Quote Link to comment Share on other sites More sharing options...
Smokeman Posted January 30, 2009 Author Share Posted January 30, 2009 Very valuable formula at that my friend. Thanks Again Quote Link to comment Share on other sites More sharing options...
Smokeman Posted February 16, 2009 Author Share Posted February 16, 2009 Here it is folks, The finished bird feeder. With the cone on the top. Thanks for your help in making the cone. Quote Link to comment Share on other sites More sharing options...
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