So down to business – doing the layout and cutting of the pots to form the conical. The first part is to figure out the layout for your conical cone. Basically your cone will be made from a circular segment that is larger in diameter than the base of the upper pot segment. The greater the diameter of the circle that will form the cone vs. the base of the pot the taller the cone. Simple enough right? So how did I figure out the diameter of that circle? Well to a significant extent that was limited by the material I was going to be using to form the cone – the sides of the 5 gallon pot.
With this figure as the upper limit I then laid out a couple of circles with a compass on some newspaper in preparation for some trial and error folding.
A key part to making the cone is cutting out a pie shaped segment from the circle you’ve just laid out – determining what size that needs to be is simple enough. You need the length around the big circle you’ve just laid out when the pie shaped segment is removed to equal the cirucmference of the bottom of the pot you’ll be using as the upper portion of the conical.
In this case the diameter of the cone I chose was 18 1/2″. Measuring these is most easily done with a very flexible tape measure such as those used for sewing. Now I should note that I added just a tad to the circumference in order to have the cone be just a bit wider at the mouth than the base of the upper pot since it’s always easier to trim material out than try to fill in significant gaps.
I decided to cut out half of the cone circle in one piece and the smaller segment, that is the other half of the cone circle less the pie shaped segment that isn’t needed for the cone in another piece. It seems to have worked out OK, but now that it’s done I wonder if it might not have been easier to have the two pieces of the cone eaually sized thus providing a greater gap between the final welds. It shouldn’t be a big deal either way, but I might try out the other variation just to see how things work out as I refine the design.
OF course if you are using a solid sheet of stainless steel you only need to remove the pie shaped segment, but the five gallon pot offered me a low cost readily available source of the steel sheet so that is what I used – thus requiring a bit more assembly work.
So that is how the template for the cone was established. I then taped it to the sides of the five gallon pot and marked out the shapes with a sharpie marker.
To cut them out I used my angle grinder with a thin abrasive cutting disk. It’s not perfect but with care it’s a pretty good result. I then cut the bottom off of the 5 gallon pot from the pot side – not the pot bottom – to free the segment.
You can check out these videos for a quick overview of how that work was accomplished.