This section shows how to fashion the cylindrical bodies of the blast furnace stoves, including the hemispherical tops.
For the the dome-shaped tops, however, I did order three of those from Plastruct at 31/2 inches diameter.
Another possible approach would have been to use a slightly wider diameter dome size and cut it down to the same diameter as the tubing; this would result in a less-rounded appearance. But I have seen both variations, sometimes even at the same location such as Gulf States Steel in Gadsden, Alabama.
To give the stoves a believable appearance, I needed to make the cylinders look like they had an outer covering of sheet steel. The seams between these metal sheets are always visible in prototype stove photos.
To create such an illusion, I wrapped a hose clamp around the tube, then used an X-ACTO® knife to scribe a line around the circumference of the cylinder. I repeated this process at 11/4-inch intervals until the lines spanned the full length of the tubular section.
Once the horizontal lines had been etched in, I attached a second hose clamp and spread the two of them apart (one at each end), using them to position a hack saw blade along the length of the tube. Then I scribed staggered vertical lines between every other pair of horizontal lines. Four rows of verticals were spaced at 90-degree angles around the cylinder, with another set of four offset vertical rows in the 'in-between' horizontal line pairs (see seam pattern diagram).
I wanted to be able to freely slide Plastruct tubing for the hot and cold blast mains, the burner inlet, and the stack outlet into optimum positions during final assembly; this meant drilling holes of diameters matching that of the tubing they needed to accommodate, in the correct locations. Two errors I identified with the Walthers Blast Furnace stove system were (1) the gas burner is much too small, and (2) there is no cold blast main pipe or inlets. I needed some outside assistance to learn the actual way in which prototype stoves are setup.
After viewing diagrams sent to me courtesy of Mike Rabbitt, I settled on the hole positions shown in the cross section diagram. The widest opening was for the hot blast outlet, the smallest for the stack outlet, with two intermediate-sized holes for the burner and cold blast inlets. I vertically placed the burner hole approximately one-half inch, and the others at one inch, from the stove bottom. (I'll discuss the modeling of the burners in a later section.)
Once the holes had been drilled I was ready to cement the hemispherical domes to the tops of each cylinder. This completed the initial construction phase of the stoves; all that remained was the catwalks and stairways. Click HERE to view a photo of the semifinished stoves.
