We made a lot of progress today. Most of the painting is done, so we could concentrate on assembly. Here’s the lower trunnion assembly with the hanger studs and knobs complete. The potato projectiles are muzzle-loaded, so they have to be pushed down toward the combustion chamber with a ramrod. The ramrod will ride in a tube above the barrel, both to simulate the “recuperator cylinder” on the real thing, and because it’s so long, there’s no other place to put it. The smaller rings on top of the cannon clamp rings will hold the tube tight. It’s 1 1/2” PVC; the ramrod is a 1 1/4” x 48” dowel.
Here’s a shot with the cannon and ramrod tube assembled. The machine screw in the side of the cannon is an electrode/spark plug for the ignition system. There’s also one on the opposite side.
Here’s a shot looking into the breech at the electrodes. You can see my “R” marks (for Rear) chiseled into the trunnion parts here. Heh – you can also see my smaller, handheld cannon on the wall rack across the garage, above my car.
Here’s a shot showing the ramrod sitting atop the cannon. The yellow line indicates the proper projectile seating depth. There’s also some extra length so it can be used as a cleaning rod.
And here’s a shot with the ramrod in its tube. It still lacks the forward bracket holding the tube and barrel together.
Now the trail assembly is going together. At the end of each member, I ran a piece of left-over 3/4” threaded rod down through, and put a plain nut on top, and an acorn nut on the bottom for a foot.
Halfway along the right arm is a bracket to hold the breech plug, so it won’t have to be set on the ground.
I bandsawed a breech plug wrench out of 3/4” baltic birch ply. The plugs tend to get stuck on these, with overtightening and fuel residue; this should be easier on the fingers.
Here’s the wrench in its bracket.
It’s on wheels!
Here’s the start of the forward ramrod tube bracket. I’m going to split this one vertically through the centerline and put 2 screws through it horizontally. I’ve got the edges laid out; next step here is to drill for the screws, then split it, then cut/sand the curves and the taper. It’s a double thickness of 3/4” birch ply.
And here it is sanded and ready for paint. It was almost 9:30, and dark, when I got to this stage, so painting can wait until morning.
Next installment: Ignition
-- The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary. - H.L. Mencken