Diving Helmet Construction

You can't build anything without the correct parts. Some parts we purchase "off the shelf", some we subcontract, and some we make in house. The U.S. Navy Helium Helmet has over 210 parts. A DESCO diving helmet (Mark V, Helium, Commercial, or Air Hat) is made up of various parts from many sources. Heavy and massive parts are generally cast from Red Brass by a local foundry. Lighter more detailed or precision parts are made on our machines by us, or sub-contractors with equipment which can make them more efficiently. Standard hardware (wiring, speakers, nuts & bolts, etc.) are purchased from industrial supply houses. Stock materials such as Acrylic for the windows, Yellow Brass for turned parts, Rubber and Leather for gaskets are all sourced locally. Every part on a helmet has some value added labor done to it before it is installed.

Cast parts are made from DESCO's patterns. The foundry places forms over the patterns and rams sand until it takes the shape of the pattern. In areas of the final casting that need to be hollow, cores made of fine sand are inserted. Molten Brass is poured into the mold to produce the parts.

We received Red Brass castings from the foundry. The parts included breastplate base rings, neckring sets, window bases & guards, breastplate loops, and telephone cups. The cast parts require some machining. They also must be sanded and buffed.

As usable parts are received or castings are machined to a usable state the parts will be stored in our parts racks until needed.

Fabricating, Machining & Finishing Parts

The helmet shells are spun by an outside supplier who specializes in metal forming. During World War Two the shells were spun in house.

The bonnet needs to have all the openings cut for the windows, telephone cup, spitcock, and elbows. Hole locations are laid out with a pattern. Cutting is done with hole saws of the correct size in a drill press.

Whether cast or brass stock the parts require machining. This could entail drilling and tapping holes, single pointing threads, cutting to size, or just making a clean surface.

Turned parts are machined from round, square, or hex Yellow Brass bar stock. These parts include breastplate studs, front door toggle bolt, canister nuts, canister sleeves, exhaust stem, exhaust bonnet, and Non-return parts.

Casting need to be machined too.

Some parts which are too large for our equipment or have special requirements are sent out for machining by a subcontractor.

Many of the machined parts still need sanding and buffing. The window frames, exhaust body, elbows, and spitcock all need to be sanded and buffed before installation. Other parts which will not be plated require further polishing. Some parts like the brails and telephone cup don't need any machining done so it is just sanding and buff/polish for them. Sanding is done on a belt sander for flat surfaces, or a sanding disk mounted in a drill press. Buffing is done with cloth hard or soft wheels on a pedestal grinder. The hard wheels have grit of different grade glued to them, while the soft wheels use a greaseless compound. High polishing is done with jeweler's rouge on a soft wheel. The bonnet shells sometimes need to be sanded a bit to seat properly in the neck ring. The bonnet lip is sanded on the hard wheel like the cast parts.

Assembly

The shell is media blasted to clean the metal and facilitate soldering. At this point it is ready to receive the other parts of the top.

When the other parts are prepared hanging of parts can commence. The neck ring is soldered in first. Then the window frames are set and soldered to the shell. The exhaust body, telephone cup, spitcock, and air & communication elbows, welding lens bracket, and lock dumbbell are then added.

The Breastplate has fewer parts but is no easier to make.

Once the helmet comes back from plating or the polishing is finished final assembly can begin.

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