Part 022: Case Rear

The Case Rear does nothing more than contain the Nozzle Guide Vanes and connect the same to the outer casing. The plans called for a mild steel... since the part is roughly 3.5" diameter, and I had only brass on hand, I elected to use it. It is exposed to significant heat, but not much stress, so I think the brass, especially after I heavily plate it with nickel, should do fine. The exhaust stacks on my radial are nickel-plated copper tube, and these have withstood high temperatures nicely.

The brass will expand very slightly more than steel and will also transfer heat better to the outer case. This may be beneficial or detrimental, I'm not sure of which! If necessary, I can replace this part at a later date with steel.

A stub of stock is held in a 6" 3-jaw chuck, and the basic shape is formed via normal turning and boring practices.

The 8 holes which allow this part to be secured to the NGV are drilled via DRO coordinates. I am converting the metric fasteners to their Imperial equivalents; in this case, the holes are drilled 4-40 through rather than M3. The NGV will eventually be drilled and tapped 4-40 to receive this part.

The outer casing, a thin sheet of SS, is fastened via 6 radially drilled and tapped holes. The plans called for M2.5, which I converted to a 3-48 thread. The setup is quick and very dirty, a rotary table (with attached chuck) is simply clamped in my permanently mounted Kurt vise. After the edge is located and the stock centered, the six holes are drilled and tapped.

Back in the lathe, the case rear is parted to the correct width. The old stock is removed, and the case rear is returned to the chuck for final cleanup.

Using my Caswell plating kit which worked so successfully on the radial engine, I gave the part a deep plating of nickel. The part is first scrubbed thoroughly with common dishwashing liquid, then soaked in hot TSP for perhaps 10 minutes. Plating was at 3VDC, 0.85 amperes, for one hour.

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