Part 1: Sir Pervicale and the Quest of the 1/2-20 Wingnut

When I had most of the steel pieces cut, I started loosely assembling them onto the allthread. That was when I remembered a weird thing about allthread: it is generally fine-thread even in sizes that are done with coarse thread. So “typical” 1/2″ bolts are threaded 1/2-13 (13 threads per inch) but allthread is 1/2-20. I was, in fact, aware of this when I bought it, and had ordered 5 nice 1/2-20 wingnuts online. My assembly visualization skills are shot, now, so I did not compute that I needed 8. No problem, there’s a big box home stuff store near my studio so I went over and discovered, just at closing time, that they stocked literally nothing in 1/2-20. At that point, I was stuck because the hardware store in Philipsburg would be closed by the time I got there. So I went to the my shop, grabbed a 1/2-20 tap, and tried to re-thread one of the existing wingnuts – a brutal operation in the best of times. I was spared having a crew of angry machinists waiting to beat me up in the afterlife, because the cheap zinc alloy of the wingnuts was crumbly and wouldn’t hold a thread. Ha Ha! Well, I have a metal lathe and some 12L10 1″ hexagonal steel, and I’ll just cut off a few pieces of that and thread them, piece of cake. 10 minutes later I had some lovely proto-bolts, and then I discovered that, while I have plenty of 1/2″ drills, I had no 27/64″ drills. Zounds and blimey, I’ll just worry about it tomorrow when the hardware store is open. So I got some bolts and a few other things and started situating where holes were to be.

Usually for this sort of thing I use “experiential assembly” – i.e.: I make one piece, then do the holes in the next by using the first piece as a template, etc. I’m just not the kind of guy who approaches something like this with a ruler or angle measure. Yes, I know how. I’m just lazy and I usually get it right so its nobody’s business except my own.

Above, you can see the basic assembly of the interior. One thing I am mildly curious about is the heat that will be escaping the front “door” and whether it will be a problem for the uprights. The uprights are going to have the allthread running through them and I expect they’ll be fine. For something like this I usually drill the holes slightly over, so I have some leeway to shift things around and make it fit. This is not a project that will be featured in the Metropolitan Art Museum’s Fine Machining gallery.

pictured: stuff

That’s basically the whole thing, right there. The gutters on the sides are the width of a brick, and the top rails are not pictured. The top is going to be a separate frame that rests on the lips of the upper cross-pieces, which I call “the lintels”

The front porch L-bracket has been cut down on the sides so there’s enough metal to keep it stiff, but I can make the porch by putting two bricks sidewise across the rails. The hard brick should be easy to replace if one cracks, just loosen the wingnuts, pop it out, pop a new one in, tighten it all up again. Since the top will be easily lifted off (held by gravity technology) it will be easy to reach inside and paint the interior with reflective paint or sealant as necessary. It’s all super basic.

I did get a bit fancy but it didn’t work. When I laid the metal and bricks out for measurement, I did not take into account that I wanted a bit of side-to-side and up-and-down space for the bricks so I could make an inner layer of kaowool felt between the interior and the bricks. My thinking was that it’d give a bit of oxidation protection and it’s cheap and easy to replace. Well, it’s not easy to replace if there’s no room for it!

I needed about 1/2″ extra for the felt, but I guess I’ll worry about that if I ever make another of these things. The hard bricks last a couple of years longer than the soft ones, so it may not be a problem. It also means I won’t be breathing anything that has gone near kaowool. There are other details I did not consider, such as maybe drilling vertically though a hard brick to make the uprights by the opening, instead of using steel that will be exposed to the forge’s heat. So what, that stuff will also last a few years and if I run the forge up to close to the melting temperature of steel, I have made an unforgivably big mistake.

The forge-astute among you are probably wondering “where will the burners go?” So, the idea for that is I will mount a 2″ steel strap along the outer side of the right hand, which will have 3 big holes to accept the burners. I’ll just use self-tapping metal screws to attach that to the verticals. Then, I’ll use a carbide circular hole cutter to cut holes in the bricks for the burners. The symmetry of the burners will be a bit weird. #1 burner will be in brick #2, #2 burner will be in brick #3, and #3 burner will be in brick #5. All burners have separate cutoff valves so that won’t be a problem. Remember, there will be an inner baffle (a brick!) to shorten the interior of the forge to 3 bricks when I am not making full-length items. I have given some thought to making a mold and casting right bricks out of mizzou, which is higher temperature refractory, but I think that’s an option if the existing bricks start to crumble.

Now I am at sort of an impasse. The next step should rightly be to install the burners, but if I do that, it means taking the old forge offline and probably recycling it. I could go ahead and make the top, but it’d be easier to get that right if I have the bottom assembled in its actual size. So I will be forge-less for a week or so.